NANGYANG RESEARCH PROGRAMME

Progress Report - Study of Feasibility of Superman Memory Crystal (EEE38)

Supervisor: Professor Yoo SeongWoo

Lincoln Yao Shu Wei

River Valley High School

1. Introduction

The reason why this study is undertaken is to evaluate the potential of the superman memory

crystal as our next generation of storage device in this information driven world. Due to the

technology of superman memory crystal and its relevant technology (e.g. Femtosecond laser

writing) still under the developmental stage, we will be using the technology available now to

evaluate the potential of the crystal. The scope of the project will be covering the possible usage

of such data storage device in large online companies such as google and average daily

consumers. This project will only be evaluating secondary data; no additional source of

information will be used. Once again, due to the superman memory crystal still under the

development stage, this project is limited to mostly evaluating the potential of the crystal with

current technology. Many assumptions of dimensions for items mentioned, since there google

does not disclose any information related to their facilities.

1.1 Aims and Objectives

Through thorough investigation and evaluation of secondary researches, this project aims to

compare and conclude the feasibility in using the superman memory as a storage device

available to both large online companies and average daily consumers. This project hopes to

give clear and logical insights on the potential usage and possible limitation of the superman

memory crystal currently and in the future.

2. Literature Review

Eternal 5D data storage by ultrafast laser writing in glass: This is a research paper that is done

by participants in SPIE, an event in America. This report is a detailed report of how the optical

storage is used, and how it works; referencing many useful sites and figures. One of the best

and most relevant report on the internet.

Wikipedia 5D optical data storage: This is a report states very basic information of the subject,

although not detailed and might not be entirely reliable, it provides a general sense of direction

and guides me in further research.

2.1 Background information

5D optical data storage (sometimes known as Superman memory crystal) is a nanostructured

glass for permanently recording 5-D digital data using femtosecond laser writing process. The

memory crystal is capable of storing up to 360 terabytes worth of data for billions of years. The

concept was experimentally demonstrated in 2013. As of 2018, the technology is in production

use by the Arch Mission Foundation. Its first and second discs were given to Elon Musk; one

disc is in his personal library, and the other was placed aboard the Tesla Roadster in space.1

1 https://en.m.wikipedia.org/wiki/5D_optical_data_storage

2.2 Description of Superman memory crystal in real life

The Superman memory crystal, also known as the 5d optical data storage, is a nano-structured

glass for permanently recording 5-D digital data using femtosecond laser writing process. It

makes use of lasers to write data in all 3 dimensions of a silica glass, and through utilizing

polarization of lights, it is able to create birefringence that creates 2 more ‘dimensions’. By using

femtosecond laser writing, a tighter focusing optics and shorter wavelength light, it makes the

data denser in the medium, involving a pit size of less than 200 nm. Combined with the fourth

and fifth dimensions provided by birefringence, which allow a single pit to store eight bits (one

byte) of information as opposed to one. This makes it possible to achieve an unprecedented

capacity of hundreds of terabytes in a single 12cm-diameter disc. Perfecting 5D storage

technology would therefore be a major step towards preserving the digital age for future

generations. Using fused silica, which has a high chemical and thermal stability. The lifetime of

5D memory is1020 years at room temperature, indicating unprecedented stability among all

techniques.2 Besides the benefits of multiplexing, 5D optical data based on nanograting can be

also erased and rewritten - which are two key features when considering data storage.

2.3 Applications in online companies using large amount of data storage (Google)

As our lives are becoming more and more centered around the internet, more data are being

uploaded onto the internet. This massive amount of information has created a need for data

storage like never before. Companies like Google are feeling the pressure of this surge of

information and are forcing them to make a change. Google researchers pointed out that users

upload over 400 hours of video every minute, which at one gigabyte per hour requires adding

one petabyte (that is 1 million Gigabytes) of data center storage capacity every day.3 Google is

currently using hard-disk drives in their data centers. However this method although popular and

cheap it is highly inefficient. Google transfers data out of these drives every 2 years to prevent

loss of information. It is also energy draining, loading energy consumption of up to 0.04W/GB.

The Superman memory crystal might be the answer to this problem. Its data density and decay

time blow other systems out of the water, however there are other aspects that has to be taken

into consideration, before it can be decided if the 5d optical data storage is the way to go for

Google right now.

2.4 Data storage density

According to estimates, Google stores about 15 exabytes of data in their data centers. Google

has fifteen data centers worldwide, containing their data to provide queries every day. However,

the data centers are huge, biggest center occupies up to 32000 square meters4 of area worth of

data storage. Data storage facilities are up to 2 meters in height. This means it would occupy up

to 64000 cubic meter of space. With 15 known data centers, in total, google is taking up to

2 https://www.5dmemorycrystal.com/technology/ 3 https://www.datacenterknowledge.com/archives/2016/05/02/google-wants-rethink-data-center-storage 4 https://www.datacenterknowledge.com/google-data-center-faq-part-2

960000 cubic meter of space to store its data. However, since we are only interested in the data

storage medium, we have to assume that only 10% of the space is used for actual data storage,

as this information is disclosed to the public. 96000 cubic meter of space is used.

The 5d optical data storage claims to be able to store 360 terabytes of data in a standard sized

disc. The dimensions of a standard sized disc is 60mm in radius and 1.2mm.

𝜋 × (60𝑚𝑚)2 × 1.2𝑚𝑚 = 1.3 × 10−5𝑚3

The 5d optical data storage takes 2.26 × 10−4𝑚3to store 360 terabytes of data.

(15 × 1024 × 1024)𝑡𝑒𝑟𝑎𝑏𝑦𝑡𝑒 ÷ 360 𝑡𝑒𝑟𝑎𝑏𝑦𝑡𝑒 × 1.3 × 10−5𝑚3 = 0.5𝑚3

The amount of space if replaced by the 5d storage is greatly reduced, however this is no

including the instruments used to write and read data into the crystal. These equipment such a

femtosecond lasers takes up a lot of space.

However a data storage needs many components, since we have only considered the size of

the storage drive, we now have to consider the two other steps, the recording and reading if data

from the drive. Currently, Google data centers use storage slots like these to store data.

2.4.1 Writing of data

For 5d optical data storages, which uses femtosecond laser writing technique and microscopic

readers. The concept of storing data optically in the bulk of non-photosensitive transparent

materials (such as fused quartz, which is renowned for its high chemical stability and resistance)

via femtosecond-laser (fs-laser) writing was first proposed and demonstrated in 1996.3, 4 This

method allows for high-capacity optical recording by multiplexing new degrees of freedom (e.g.,

intensity, polarization, and wavelength). This development in data storage is based on the

introduction of gold or silver nanoparticles, which are embedded within the material.5The

plasmonic properties of these nanoparticles can then be exploited.6, 7 More recently,

polarization-multiplexed writing has been demonstrated by using self-assembled nanogratings,

which are produced via ultrafast-laser writing in fusedquartz.8, 9 These nanogratings, which

comprise 20nm-thick lamina structures embedded within the material,10–12 are resistant to high

temperatures.13 Despite several attempts to explain the physics of this peculiar self-organization

process, the formation of the nanostructures remains a mystery.

The femtosecond laser writing machines are generally big. An example of this femtosecond

laser-writing machine is the Workshop of photonics, Laser Micromachining Workstation for

Laboratory FemtoLAB5 (Appendix Fig.3). Its size is up to 1.3m x 1m x 0.8m=1.04m3

2.4.2 Reading of data

For reading of data, a combination of optical microscope and a polarizer needs to be used.6 This

is also known as polarized light microscopy. Simple techniques include illumination of the sample

with polarized light. Directly transmitted light can, optionally, be blocked with a polarizer oriented

at 90 degrees to the illumination. More complex microscopy techniques that take advantage of

5 https://www.wophotonics.com/product/laser-micromachining-workstation-femtolab/ 6 https://en.m.wikipedia.org/wiki/5D_optical_data_storage

polarized light include differential interference contrast microscopy and interference reflection

microscopy.

Currently, primary manufacturers of polarization microscopes include Nikon, Olympus, Zeiss and

Leitz. Olympus BX51 Fluorescence Microscope (Appendix Fig.2) is often used. Only taking

about 1m3 of space. However, automation of the microscope needs to be done in order for this

to be utilized in the reading of 5d optical data storages.

2.4.3 Processors

Any kind of data storage or memory requires processors, also known as central processing unit.

The fundamental operation of most CPUs, regardless of the physical form they take, is to

execute a sequence of stored instructions called a program. The instructions to be executed are

kept in some kind of computer memory. Nearly all CPUs follow the fetch, decode and execute

steps in their operation, which are collectively known as the instruction cycle. Therefore only with

these processors are the data read and extracted can be used, or relevant data can even be

found. Assuming processors of the 5d optical data storage used is same as Google’s data

storage, POWER8 Processor and NIVIDA GPU are kept (Appendix Fig.1). They are assumed

(0.2 x 0.3 x 0.1) m3.

2.4.4 Estimations

If each small piece of the crystal, a size fit for the microscope is used, each piece would be

roughly 0.4x 10-5 m3.

An estimated 125000 of these pieces would be required to store the data present currently. If

we simply consider them put together, each piece of crystal would take another 2m3 of space.

This would tally up to 255750m3 amount of space. Which would be 704250m3 less than the

amount of space Google is currently using. However, these are assumptions made with devices

currently available. These machines or instruments are not made or customized to be used in a

mass data storage center. If companies invest to research and modify parts to be compact and

suit the use of mass data storage, much more space could be saved. There are things that are

not taken into consideration as well, such as cooling devices, workspace for maintenance

workers and so on.

3. Work accomplished

3.1 Timeline

1. Research on how the 5d optical data storage works

2. Find out how data is currently stored

3. How is 5d optical data storage better than current methods

4. How to incorporate 5d optical data storage into current data centers

5. How much energy 5d optical data storage uses

6. How much it costs for maintenance

7. How its slow decay character can be utilized

3.2 Findings

From reading a collection of different articles, I found out more about how 5d optical data storage

make use of refraction of light to create the 5d instead of just 3d optical data storage. This helped

in creating the background information, and possibly help us brainstorm for innovations in future

reports.

I also read many articles on light polarizing microscope, which is used to read the binary code

in the 5d optical data storage. The findings on different type of light polarizing microscope and

their information helped us in determining the size of a data storage system using the 5d optical

data storage. Findings about central processing unit also helped us in determining how a data

system is created and how the 5d optical data storage system can become a reality for huge

information companies. Findings on femtosecond laser writers that can process information to

precision is contributed to the estimation and concept of a data storage system based on 5d

optical data storage as well

3.3 Conclusion

Purely based on the amount of space that are saved by using 5d optical data storage, information

companies should be investing in this technology. As the amount of information being uploaded

onto the internet is growing exponentially, finding a solution that saves space is crucial. The 5d

optical data storage is a perfect solution to this problem.

3.4 Schedule for further investigation

1. Research on sped of writing and reading of data

2. How to increase speed of writing and reading of data or what size of is suitable such that

writing and reading of data can be fast enough

4. Appendix

Fig. 1

Fig. 2

Fig. 3

NANGYANG RESEARCH PROGRAMME

Progress Report - Study of Feasibility of Superman Memory Crystal(EEE38)

Supervisor: Professor Yoo SeongWoo

Lincoln Yao Shu Wei, You Zeyuan

River Valley High School

Introduction

The reason why this study is undertaken is to evaluate the potential of the superman

memory crystal as our next generation of storage device in this information driven world.

Due to the technology of superman memory crystal and its relevant technology (eg.

Femto laser writing) still under the developement stage, we will be using the technology

available now to evaluate the potential of the crystal. The scope of the project will be

covering the possible usage of such data storage device in large online companies such

as google and average daily consumers. This project will only be evaluating secondary

data, no additional source of information will be used. Once again, due to the superman

memory crystal still under the development stage, this project is limited to mostly

evaluating the potential of the crystal with current technology.

Aims and Objectives

Through thorough investigation and evaluation of secondary researches, this project

aims to compare and conclude the feasibility in using the superman memory as a

storage device available to both large online companies and average daily consumers.

This projects hopes to give clear and logical insights on the potential usage and

possible limitation of the superman memory crystal currently and in the future.

1. Description of Superman memory crystal

The Superman memory crystal, also known as the 5d optical data storage, is a

nano structured glass for permanently recording 5-D digital data using femtosecond

laser writing process. It makes use of lasers to write data in all 3 dimensions of a silica

glass, and through utilising polarisation of lights, it is able to create birefringence that

creates 2 more ‘dimensions’. By using femtosecond laser writing, a tighter focusing

optics and shorter wavelength light, it makes the data denser in the medium , involving

a pit size of less than 200 nm. Combined with the fourth and fifth dimensions provided

by birefringence, which allow a single pit to store eight bits (one byte) of information as

opposed to one. This makes it possible to achieve an unprecedented capacity of

hundreds of terabytes in a single 12cm-diameter disc. Perfecting 5D storage technology

would therefore be a major step towards preserving the digital age for future

generations. Using fused silica which has a high chemical and thermal stability. The

lifetime of 5D memory is years at room temperature, indicating unprecedented1020

stability among all techniques. Besides the benefits of multiplexing, 5D optical data 1

based on nanogratings can be also erased and rewritten - which are two key features

when considering data storage.

The 5D optical data storage requires:

Writing of data

For 5d optical data storages, which uses femtosecond laser writing technique and

microscopic readers. An example of this femtosecond laser writing machine is the

Workshop of photonics, Laser Micromachining Workstation For Laboratory FemtoLAB2

(fig.1).

Fig1.

Reading of data

For reading of data, a combination of optical microscope and a polarizer needs to be

used other than the femto laser machine. This is also known as polarised light 3

microscopy. Simple techniques include illumination of the sample with polarized light.

Processors

Any kind of data storage or memory requires processors, also known as central

processing unit. It is required to process the raw data that is read by the microscope

and sort out the information that is required.

1 https://www.5dmemorycrystal.com/technology/ 2 https://www.wophotonics.com/product/laser-micromachining-workstation-femtolab/ 3 https://en.m.wikipedia.org/wiki/5D_optical_data_storage

2.2 Application in daily usage by average consumers

There are 3 main types of storage device today, optical data storage, magnetic data

storage and flash data storage. This chapter will be comparing current data storage

devices to the superman memory crystal as a potential data storage device in daily

lives.

Magnetic storage:

magnetic storage refers to any type of data storage using a magnetized medium.

the changes in magnetization from region to region in the magnetic storage device are

detected and recorded as zeros and ones as binary data by a head that is moving very

close to it. Magnetic storage is a form of non-volatile storage. Several types of

magnetized media are used in computer systems, including magnetic tape, floppy

disks and hard disk drives(HDD).

Optical data storage:

Optical storage refers to any data storage that is written and read in lasers. Optical

data storage is a also a form of non-volatile storage.Typically, the data is written to

optical media, such as DVDs and bluray disks.

Flash storage:

Flash storage is a data storage technology based on high-speed, electrically

programmable memory. It is named flash because of its speed in writing and erasing

data and performing random operations. It is non-volatile. The type of flash storage that

is used today includes solid state drives(SSD) and thumbdrives.

To simplify the comparison, a popular and highest performing device will be chosen to

represent each type of storage type. For magnetic storage Seagate BarraCuda Pro 4

will be chosen. For flash storage, intel’s SSD optane 905P is chosen, optical data 5

storage will be represented by the superman memory crystal itself.

4 https://www.seagate.com/sg/en/internal-hard-drives/hdd/barracuda/ 5 https://www.intel.com/content/www/us/en/products/memory-storage/solid-state-drives/consumer-ssds/optane-ssd-9-series/optane-ssd-905p-series.html

To evaluate its feasibilities in detail, the devices will be compared in terms of their

1. data storage capacity and its physical size

2. Data extraction speed and devices used to extract data

3. Affordability and power consumption

4. Lifespan and security of information

2.2.1 Comparison of storage capacity and physical size of storage device

Seagates BarraCuda Pro have a maximum storage of 14TB (14 x 10 9 bytes), with a

areal density of 1077 Gb/in 2. 6

Intel’s Optane 905p can store up to 1.5 Tb of data, with half height form factor(1.625"

high, 5 1/4" wide, and 8-inch deep).

The superman memory crystal in comparison are able to store 360 TB of data in

, similar to the size of a USB thumb drive, a much larger data storage and.26 m2 × 10−4 3

higher information density compared to both the SSD drive and hard drive.

2.2.2 Data extraction speed and devices used to extract information

The intel optane 905P SSP are able to acheive a sequential read and write speed of up

to 2,600 / 2,200 MB/s. While its random read and write speed can acheive 575,000 /

550,000 IOPS. 7

Seagates Barracuda Pro are able to achieve a platter rotation of 7200 RPM which gives

a read and write speed of 220MB/s.

Both of this devices can be used as a internal computer storage or external storage that

can be directly connected to the computer with a USB cable.

The superman memory crystal is a type of optical data storage which uses

femtosecond(10 -15 s) laser writing. The highest frequency laser used so far in optical

data storage. It requires complex machinary such as the Olympus BX51 Fluorescence

Microscope(fig.2) is often used. Taking up to 1m3 of space. Its fastest reading speed is

still unclear, but logically speaking, reading from such a high density device using

femtolaser would be much slower compared to the rest of the data storage devices.

6 https://www.anandtech.com/show/13340/seagate-barracuda-pro-14tb-hdd-review 7 https://www.tomshardware.com/reviews/intel-optane-ssd-905p,5600.html

2.2.3 Affordability and power consumption The intel optane 905P cost about $1300 US dollars online, its power consumption

is about 5.4 watts on idle mode. 8

The seagate barracuda Pro cost about $580 US dollar online, and have a power

consumption of 4.9 watts in idle mode.

The superman memory crystal in comparison, its price have to be determined by the

price of the femtosecond laser and the technological process input to acheive

automated reading and writing process.

In estimation, a current Olympus BX51 Fluorescence Microscope costs about 16,000

dollars, and a Power 8 processor cost about a total of 10,000 - 15,000 dollars, which is

inclusive of CPU, Ram and PSU. The total price of this already about 30,00 dollars,

which is only inclusive of the basic material required. It would require a computer

system designed to let all the parts run together smoothly and many other necessaities.

2.2.4 life span and security of information

The 905P uses Intel’s Optane non-volatile memory on board, which in turn uses the

NVMe protocol for passing data back and forth with your computer. 9

The drive carries a 5-year warranty, the 905P is good for 10 full drive writes a day. If

that’s 10 writes per day for the five years of the warranty,its an endurance rating of

around 1.75 PBW (PetaBytes Written), or 1,750 TBW (TeraBytes Written).The 10TB

Barracuda Pro is warrantied for five years at 220TB worth of writes per year, or 1100TB

over the warranted lifespan. The superman memory crystal, according to the 10

researchers at Southampton University can store information of up to 13.8 billion year

lifespan at 190 degrees Celsius. However, regarding its ability to erase current data and

rewrite is unclear, this makes the comparison between the current data storing

technology and superman memory crystal more abstract. The superman memory

8 https://www.legitreviews.com/intel-optane-ssd-905p-960gb-drive-review_206944/7 9 https://www.pcworld.com/article/3314983/intel-905p-nvme-ssd-review-blazing-random-access-and-amazing-endurance-for-a-hefty-price.html 10 https://www.pcworld.com/article/3099243/seagate-barracuda-pro-10tb-hard-drive-review-vast-and-amazingly-fast-for-a-hard-drive.html

crystal are able to store 360TB of data for 13.8 billion years, while the current data

storage technology are able to store 1100-1800 TB of data over the course of 5 years

under warranty. The lifespan of this storage devices is dependent on the purpose of its

usage.

You Zeyuan 

Work accomplished 

Timeline  

1. Research on the basics of how the superman memory crystal works 2. Researched on the machinery required to utilise the superman memory 

crystal  3. Researched on the current consumer data storage devices such as 

magnetic and flash storage 4. Comparison between storage capacity and density, data extraction 

speed, affordability and power consumption, lifespan and security of information of the devices. 

Experiments carried out - No experiments carried out 

Data collected - No data collected 

Analysis of data - Data of pricing information of the devices are compared - Data of speed of extraction of data of the devices are compared - Data of maximum information storage are compared - Data of maximum amount of information to be erased and rewitten are 

compared Findings From reading the articles and reports on superman memory crystal, I managed to learn that the superman memory crystal is a type of optical storage device and is the very first that can store up to ‘5 dimensions’. This gave me an general idea of how the project should head towards, since the objective of this project is to evaluate the potential of the superman memory crystal, i believe it is necessary to make comparison between the current storage devices and the superman memory crystal. Through research, I realised that the current storage types can be generally split into two types, large concentrated data storage centres and average consumer usage. 

I did thorough research on types of physical data storage devices that is used by average consumers today, whether its external storage device that can be purchased individually or internal devices that is already inside computers purchased. I found out that the most commonly used storage device is either magnetic storage devices such as hard drives or electric, programmable flash drives. In order to evaluate the potential of superman memory crystal in the consumer field, i decided to compare between this 5D optical data storage technology to the current flash or magnetic memory. Standing from a consumer point of view, i compared them in terms of total storage capacity, speed, price and lifespan, to gain a better understanding of the potential of superman memory crystal.  Findings on the technology required to for the crystal allows me to roughly estimate the price required to use the crystal and compare it to the price of flash and magnetic drives in the market. Finding on maximum data storage, data density and lifespan of todays storage device allows me to gauge how much more data can be stored in the superman memory crystal, and how much longer can it last compared to today’s data storage devices.   Finding on the device(femto laser and polarised microscope) used to extract data from the crystal and how fast data is extracted from other storage devices allow me to compare the data extraction speed. All this contributes to the evaluation of feasibility of superman memory crystal in the field of daily consumers. Conclusions made 

Based on the estimated performance of the superman memory crystal with current technology, although it is able to store much larger amount of data and have much longer lifespan in comparison to current data technology, it lacks speed of data extraction and it is much more expensive than the other devices. Further investigation and conclusion should be taken based off future developement of such technology. 

Schedule for further investigation - More in depth conclusion will be made based on the raw data collected in each 

section of the comparison - More investigation will be done to evaluate the feasibility of the superman 

memory crystal as a record of the human civilisation into the distant future.  

  

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/297892219

Eternal 5D data storage via ultrafast-laser writing in glass

Article · March 2016

DOI: 10.1117/2.1201603.006365

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10.1117/2.1201603.006365

Eternal 5D data storage viaultrafast-laser writing in glassPeter Kazansky, Ausra Cerkauskaite, Martynas Beresna,Rokas Drevinskas, Aabid Patel, Jingyu Zhang, andMindaugas Gecevicius

Information storage based on the introduction of nanostructures intofused quartz using a femtosecond laser could ensure all that we havelearned will not be forgotten.

Compared with paper or clay, digital data storage is not verydurable. As such, securely storing large amounts of informa-tion over even the relatively short timescale of 100 years—comparable to the human memory span—is a challengingproblem.1 Conventional optical-data-storage technology of thetype employed in CDs and DVDs has reached capacities of hun-dreds of gigabits per square inch. However, the lifetime of thismedia is limited to a decade as a result of unavoidable degrada-tion suffered by the data layer. More futuristic DNA-based datastorage is capable of holding hundreds of terabytes (Tb) of dataper gram, but its durability is limited.2

The concept of storing data optically in the bulk of non-photosensitive transparent materials (such as fused quartz,which is renowned for its high chemical stability and resis-tance) via femtosecond-laser (fs-laser) writing was first pro-posed and demonstrated in 1996.3, 4 This method allows forhigh-capacity optical recording by multiplexing new degrees offreedom (e.g., intensity, polarization, and wavelength). This de-velopment in data storage is based on the introduction of gold orsilver nanoparticles, which are embedded within the material.5

The plasmonic properties of these nanoparticles can thenbe exploited.6, 7 More recently, polarization-multiplexed writ-ing has been demonstrated by using self-assembled nanograt-ings, which are produced via ultrafast-laser writing in fusedquartz.8, 9 These nanogratings, which comprise 20nm-thick lam-ina structures embedded within the material,10–12 are resistantto high temperatures.13 Despite several attempts to explain thephysics of this peculiar self-organization process, the formationof the nanostructures remains a mystery.14, 15

Based on this behavior, we have developed a method ofdata storage that makes use of three spatial and two optical

Figure 1. 5D optical data storage, written in fused quartz using a fem-tosecond laser. Three spatial dimensions and two optical ones (the slow-axis orientation and the retardance) are exploited. Each voxel containsa self-assembled nanograting that is oriented in a direction perpendic-ular to the light polarization. The distance between two adjacent spotsis 3.7�m and the distance between each layer is 20�m. E: Electric fieldof light wave. Arrow: Polarization direction.

dimensions.16 On the macroscopic scale, the self-assemblednanostructures behave as uniaxial optical crystals with negativebirefringence. The alignment of the nanogratings gives rise tooptical anisotropy (a form of birefringence) of the same order ofmagnitude as positive birefringence in crystalline quartz.

In conventional optical storage such as DVDs, data is storedby burning tiny pits in one or more layers of the plastic disc,thereby making use of three spatial dimensions. We have alsoexploited two additional (optical) dimensions. When the data-recording femtosecond laser marks the glass, it makes a pit witha nanograting. This nanograting produces birefringence that ischaracterized by two additional parameters. The slow-axis ori-entation introduces a fourth dimension, and the strength ofretardance—defined as a product of the birefringence and thelength of the structure—forms a fifth dimension. These two pa-rameters are controlled during recording by the polarization andlight intensity, respectively. By adding these additional opticaldimensions to the three spatial coordinates, we achieve 5D opti-cal data storage: see Figure 1.

Continued on next page

10.1117/2.1201603.006365 Page 2/3

We have recorded the first digital documents (includingcopies of the Universal Declaration of Human Rights, New-ton’s Opticks, the Magna Carta, and the King James Bible) acrossup to 18 layers using optimized parameters (light pulses withenergies of 0.2�J and a duration of 600fs at a repetition rateof 500kHz): see Figure 2. To test the durability of this data-storage mechanism, we used accelerated aging measurements(see Figure 3). These tests reveal that the decay time of thenanogratings is 3�1020˙1 years at room temperature (303K),showing the unprecedentedly high stability of nanostructuresimprinted in fused quartz. Even at elevated temperatures of462K, the extrapolated decay time is comparable to the age ofthe Universe (13.8 billion years). Based on the tests, we believethat these copies could survive the human race.9

The addition of more states of polarization and intensities—currently limited by the resolutions of the slow axis orientation(4:7

◦) and the retardance (5nm)—could enable more than onebyte (8 bits, or 256 possible combinations) per modification spotusing the same birefringence measurement system. By recordingdata with a 1.4NA (numerical aperture) objective and a shorterwavelength (250–350nm), recording a disc with a 360Tb capacity(more than 7000 times today’s 50Gb double-layer Blu-ray capac-ity) could be made possible.

We have developed an extremely durable 5D data-storagetechnique based on the imprinting of nanostructures in silicaglass via femtosecond-laser writing. This technology, which wehave coined ‘Superman memory crystal,’ could be produced ona commercial scale for organizations with large archives (e.g., na-tional archives, museums, libraries, and private organizations).We believe that our method will also prove attractive for theconsumer market if the cost of hardware (particularly the ex-pensive femtosecond laser) is reduced.17 Additionally, a numberof projects (such as Time Capsule to Mars, MoonMail, and theGoogle Lunar XPRIZE)18–20 could benefit from the technique’sextreme durability, which fulfills a crucial requirement for stor-

Figure 2. Copies of (a) the King James Bible and (b) the Magna Cartaimprinted in glass.

Figure 3. Arrhenius plot of the nanograting decay rate. The black dotsindicate measured values and the red dots are calculated based on fit-ting results, showing the extrapolated lifetime of the stored data. Thegray shaded zone indicates the tolerance of extrapolated values. Basedon these results, the nanogratings would last for the current lifetime ofthe Universe (� D 13:8 billion years) at a temperature (T) of 462K. Theinset shows the decay of the retardance strength over time at differentannealing temperatures (900, 1000, and 1100◦C).

age on the Moon or Mars. With this technology, we may havefinally achieved information immortality.21 In our future work,we plan to improve write speeds and to develop a microscope-free disc drive for data readout.

Author Information

Peter Kazansky, Ausra Cerkauskaite, Martynas Beresna,Rokas Drevinskas, Aabid Patel, Jingyu Zhang, andMindaugas GeceviciusOptoelectronics Research CentreUniversity of SouthamptonSouthampton, United Kingdom

References

1. M. C. Elwenspoek, Long-time data storage: relevant time scales, Challenges 2,pp. 19–36, 2011.2. G. M. Church, Y. Gao, and S. Kosuri, Next-generation digital information storage inDNA, Science (337), p. 1628, 2012.3. E. N. Glezer, M. Milosavljevic, L. Huang, R. J. Finlay, T.-H. Her, J. P. Callan, andE. Mazur, Three-dimensional optical storage inside transparent materials, Opt. Lett. 21,pp. 2023–2025, 1996.4. M. Watanabe, S. Juodkazis, H. B. Sun, S. Matsuo, H. Misawa, M. Miwa, andR. Kaneko, Transmission and photoluminescence images of three-dimensional memory invitreous silica, Appl. Phys. Lett. 74, pp. 3957–3559, 1999.

Continued on next page

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5. P. Zijlstra, J. W. M. Chon, and M. Gu, Five-dimensional optical recording mediatedby surface plasmons in gold nanorods, Nature 459, pp. 410–413, 2009.6. A. Royon, K. Bourhis, M. Bellec, G. Papon, B. Bousquet, Y. Deshayes, T. Cardinal,and L. Canioni, Silver clusters embedded in glass as a perennial high capacity opticalrecording medium, Adv. Mater. 22, pp. 5282–5286, 2010.7. A. Podlipensky, A. Abdolvand, G. Seifert, and H. Graener, Femtosecond laser as-sisted production of dichroitic 3D structures in composite glass containing Ag nanoparti-cles, Appl. Phys. A. 80, pp. 1647–1652, 2005.8. Y. Shimotsuma, M. Sakakura, P. G. Kazansky, M. Beresna, J. Qiu, K. Miura,and K. Hirao, Ultrafast manipulation of self-assembled form birefringence in glass, Adv.Mater. 22, pp. 4039–4043, 2010.9. J. Zhang, M. Gecevicius, M. Beresna, and P. G. Kazansky, Seemingly unlimitedlifetime data storage in nanostructured glass, Phys. Rev. Lett. 112, p. 033901, 2014.10. P. G. Kazansky, H. Inouye, T. Mitsuyu, K. Miura, J. Qiu, K. Hirao, and F. Star-rost, Anomalous anisotropic light scattering in Ge-doped silica glass, Phys. Rev. Lett. 82,pp. 2199–2202, 1999.11. Y. Shimotsuma, P. G. Kazansky, J. Qiu, and K. Hirao, Self-organized nanogratingsin glass irradiated by ultrashort light pulses, Phys. Rev. Lett. 91, p. 247705, 2003.12. R. S. Taylor, C. Hnatovsky, E. Simova, P. P. Rajeev, D. M. Rayner, and P. B.Corkum, Femtosecond laser erasing and rewriting of self-organized planar nanocracks infused silica glass, Opt. Lett. 32, pp. 2888–2890, 2007.13. E. Bricchi and P. G. Kazansky, Extraordinary stability of anisotropic femtoseconddirect-written structures embedded in silica glass, Appl. Phys. Lett. 88, p. 111119, 2006.14. S. Richter, C. Miese, S. Doring, F. Zimmermann, M. J. Withford, A.Tunnermann, and S. Nolte, Laser induced nanogratings beyond fused silica—periodicnanostructures in borosilicate glasses and ULETM, Opt. Mater. Express 3, pp. 1161–1166, 2013.15. M. Lancry, B. Poumellec, J. Canning, K. Cook, J.-C. Poulin, and F. Brisset, Ultra-fast nanoporous silica formation driven by femtosecond laser irradiation, Laser Photon.Rev. 7, pp. 953–962, 2013.16. J. Zhang, A. Cerkauskaite, R. Drevinskas, A. Patel, M. Beresna, and P. Kazansky,Eternal 5D data storage by ultrafast laser writing in glassPresented at SPIE Photonics West, 2016.17. http://longnow.org/about/ The Long Now Foundation. Accessed 3 March2016.18. http://www.timecapsuletomars.com/ Time Capsule to Mars. Accessed 1March 2016.19. https://www.astrobotic.com/moon-mail MoonMail. Accessed 1 March 2016.20. http://lunar.xprize.org/ Google Lunar XPRIZE. Accessed 1 March 2016.21. http://singularityhub.com/2016/02/25/have-we-finally-achieved-information-immortality/ Have we finally achieved information immortality? Accessed1 March 2016.

c 2016 SPIE

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5D Data Storage

by Ultrafast Laser Nanostructuring in Glass

Jingyu Zhang*, Mindaugas Gecevičius, Martynas Beresna, Peter G. Kazansky

Optoelectronics Research Centre, University of Southampton, SO17 1BJ, United Kingdom

jz2e11@orc.soton.ac.uk

Abstract: The high-density five dimensional data storage with ultrafast laser writing is

demonstrated. The text file is recorded by polarization controlled self-assembled form

birefringence and retrieved in glass opening the era of unlimited lifetime data storage. © 2013 Optical Society of America OCIS codes (140.3390) Laser materials processing, (210.0210) Optical data storage

The idea of the optical memory based on femtosecond laser writing in the bulk of transparent material was

first proposed in 1996 [1,2]. More recently self-assembled nanogratings produced by ultrafast laser writing in

glass were proposed for the polarization multiplexed optical memory, where the information encoding would

be realized by means of two birefringence parameters, i.e. the slow axis orientation (4th dimension) and

strength of retardance (5th dimension), in addition to three spatial coordinates [3,4]. The slow axis

orientation and the retardance can be controlled by polarization and intensity of the incident beam

respectively [5]. The unprecedented parameters including 360 TB/disc data capacity, thermal stability up to

1000°C and practically unlimited lifetime [6,7]. However the implementation of digital data storage, which is

a crucial step towards the real world applications, has not been demonstrated by ultrafast laser writing. Here

we successfully recorded and retrieved a digital copy of the text file in 5D using polarization controlled self-

assembled ultrafast laser nanostructuring in silica glass.

The experiments were performed with a femtosecond laser system Pharos (Light Conversion Ltd.)

operating at 1030 nm and delivering 8 µJ pulses of 280 fs at 200 kHz repetition rate. The intensity

distribution at the focal plane was modulated via a spatial light modulator (SLM), which split the incident

light into 256 beams. The hologram generated on the SLM was reimaged via a 4-f optical system on the back

pupil of the objective (Fig. 1 (a)). In addition, a half-wave plate matrix, imprinted by the laser

nanostructuring of fused silica, was added to the 4-f optical system for the motion free polarization control.

The laser beam was focused with a 1.2 NA water immersion microscope objective at the depth of 140 µm

below the surface of the silica glass sample mounted on a three-axial translation stage (ABL1000,

Aerotech Ltd.).

Fig. 1. (Color online) (a) 5D optical storage writing setup: femtosecond laser, spatial light modulator (SLM), Fourier lens (FL),

half-wave plates matrix (λ/2 M), dichroic mirror, 1.2 NA water immersion objective, silica glass sample, translation stage. (b) Color-coded slow axis orientation of the half wave-plates matrix imprinted in silica glass.

The combination of the SLM and a half-wave plate matrix allowed the removal of relatively slow rotating

and moving components for retardance and slow axis orientation control (Fig. 1 (a)). An adapted weighted

Gerchberg-Saxton algorithm was used to set the split beam energy at several levels at the back focal plane of

the objective [3]. Combined with a phase distribution of Fresnel lens, various levels of intensity at different

depths of the focal plane could be achieved. The polarization direction was controlled by the half-wave plates

matrix (Fig. 1 (b)), where beams passing through the selected segment can generate the targeted polarization

state.

For the demonstration of this technology, the copy of this abstract was recorded into two different levels

of retardance (1 bit) and four slow axis orientations (2 bits). As a result each laser imprinted spot stores 3 bits

of information. The digital copy of the recoded text was divided into the matrix in three planes written at

different depth with the distance of 5 µm between the planes (Fig. 2 (a)).

The read-out of the recorded text file was achieved by a BX51 (Olympus Inc.) optical microscope based

quantitative birefringence measurement system (CRi Abrio). Both the slow axis and retardance distributions

of the birefringent spot array were successfully retrieved after each sequence (Fig. 2 (b)).

Fig. 2. (Color online) (a) Birefringence measurement of the data recorded in three separate layers. (b) slow axis (left) and retardance (right) distribution measured with 60× magnification.

In conclusion, we experimentally demonstrated the recording and read-out processes of 5D optical data by

femtosecond laser writing. The data recording was significantly simplified by replacing the conventional

control of the writing beam energy and polarization with a spatial light modulator and a specially designed

laser imprinted half-wave plate matrix. This demonstration is a crucial step towards commercialization of

ultrafast laser based optical data storage.

References

1. E. N. Glezer, M. Milosavljevic, L. Huang, R. J. Finlay, T. H. Her, J. P. Callan, and E. Mazur, "Three-

dimensional optical storage inside transparent materials.," Optics Letters 21, 2023–2025 (1996).

2. P. Zijlstra, J. W. M. Chon, and M. Gu, "Five-dimensional optical recording mediated by surface plasmons in

gold nanorods.," Nature 459, 410 (2009).

3. Y. Shimotsuma, M. Sakakura, P. G. Kazansky, M. Beresna, J. Qiu, J. Qiu, K. Miura, and K. Hirao, "Ultrafast

manipulation of self-assembled form birefringence in glass," Advanced Materials 22, 4039–4043 (2010).

4. M M -organization

in glass driven by ultrashort light pulses," Applied Physics Letters 101, 053120 (2012).

5. E. Bricchi, B. G. Klappauf, and P. G. Kazansky, "Form birefringence and negative index change created by

femtosecond direct writing in transparent materials," Optics Letters 29, 119–121 (2004).

6. E. Bricchi and P. G. Kazansky, "Extraordinary stability of anisotropic femtosecond direct-written structures

embedded in silica glass," Applied Physics Letters 88, 111119 (2006).

7. R. S. Taylor, C. Hnatovsky, E. Simova, P. P. Rajeev, D. M. Rayner, and P. B. Corkum, "Femtosecond laser

erasing and rewriting of self-organized planar nanocracks in fused silica glass," Optics Letters 32, 2888 (2007).