braggrate™ raman filters -...

BragGrate™ Raman FiltersVolume Bragg Gratings

for Ultra-low Frequency Raman Spectroscopy

BragGrate™ Raman FiltersVolume Bragg Gratings

for Ultra-low Frequency Raman Spectroscopy

OptiGrate Proprietary and Confidential

Ultra Low Frequency (ULF) Raman SpectroscopyUltra Low Frequency (ULF) Raman Spectroscopy

Selected applications of ULF Raman spectroscopy Pharmaceutical polymorphs LA modes of polymer Semiconductor lattices and nanostructures Material : phase/structure Metal Halides Gases Carbon nanotubes Micro, nano-crystallites

www.optigrate.com OptiGrate Confidential 2

Low-frequency Raman is an indispensable analytical tool in multiple areas of scientific research Low-frequency Raman bands (lower than 50 cm-1) exist in certain proteins. They are dependent upon the

conformation of the protein molecule, but are relatively independent of the form of the sample, i.e., whether it is a film or a crystal.

In amorphous glasses, most of the Raman spectra present a low frequency response called "boson peak". Much minerals present low frequency vibration modes, i.e. sulfur between 0 and 250 cm-1, or organic materials like

L-Cystine between 0 and 800 cm-1. Single-wall and multi-wall carbon nanotubes exhibit radial breathing mode (RBM) vibrations in the range 150–200

cm-1 which are used to characterize diameter distribution and overall quality of nanotubes as well as influence of external factors.

Quality of semiconductor multi-layered structures (superlattices) is assessed by observing folded acoustic (FA) modes in the range 0–100 cm-1.

The Relaxation modes in liquids, binary mixtures and solutions, in the range 0–400 cm-1, help to determine their dynamic structure.

Notch Filter Linewidth and Low Frequency Raman SpectroscopyNotch Filter Linewidth and Low Frequency Raman Spectroscopy

Notch filters reject scattered Rayleigh light that “overshadows” good signalBandwidth of notch filter limits the lower range of frequencies to be measuredBragGrate™ Notch Filters enable Rayleigh light rejection as close as 5 cm-1 from the laser line

Notch Filter rejects Rayleigh light


Source: world wide web

Volume Bragg Gratings as narrow line optical Raman filtersVolume Bragg Gratings as narrow line optical Raman filters


Spectral width of RBGReflecting Volume Bragg Grating (RBG)

0.01

0.1

1

10

0 2 4 6 8 10

Spectral W

idth (FWHM) [nm

]

Thickness [mm]

Wavelength, nm500 1000 1500

Reflecting Volume Bragg Gratings as Raman Notch FiltersDiffraction Efficiency (DE) up to 99.99% (standard optical density: OD>3 and OD>4)Spectral Bandwidth (FWHM) < 5 cm-1

Angular Selectivity (FWHM) < 5 mradWavelength range 400 nm to 2 µm Standard: 488, 514, 532, 633, 785, 1064 nm In production: 405, 442, 458, 473, 491, 552, 561, 568,

588, 594, 660, 880, 1550 nm Any custom wavelength can be fabricated

Grating Thickness: 2-3 mmStandard BNF dimensions: 11×11 and 12.5×12.5 mm2 (up to 25×25 mm2)No time degradation: stable up to 400C and any type of optical and ionizing radiation

ADVANTAGES of BragGrate™ Raman FiltersUltra-low frequency measurement down to 5 cm-1 with single stage spectrometers Simultaneous measurements of both Stokes and anti-Stokes Raman bandsNo polarization dependenceEnvironmentally stable, no humidity degradationNo degradation up to 400ºC Stable to any type of optical and ionizing radiation

Linewidth of BragGrate™ notch filter vs thin film notch filterLinewidth of BragGrate™ notch filter vs thin film notch filter


1E-08

1E-07

1E-06

1E-05

1E-04

1E-03

1E-02

1E-01

1E+00760 770 780 790 800 810

Opt

ical

Den

sity

Wavelength [nm]

TFF Notch

2x BNF

1E-081E-071E-061E-051E-041E-031E-021E-011E+00

784.5784.75 785 785.25785.5

Opt

ical

Den

sity

Wavelength [nm]

Spectral profiles of the narrowest thin film filter available on the market and BragGrate Notch Filter (BNF). The bandwidth of a typical BNF is about 100-200 pm, whereas bandwidth of TF filters can’t be narrower than 2-3 nm. Optical density of single BNF is limited to about OD4 and, thus, to provide sufficient Rayleigh light suppression depending on the measurement wavelength 2 to 3 filters have to be used in sequence

BNFs can be (optional) mounted in Ø1” round aluminum holders for easy use with standard opto-mechanical assemblies

BragGrate™ Bandpass Filter (laser line cleaning)BragGrate™ Bandpass Filter (laser line cleaning)

To achieve ULF Raman measurements, the laser spectral noise has to be removed as close as possible to the laser line. Standard Bandpass filters have the line width of 200-300 cm-1 and, thus, all spectral noise below 200 cm-1 would be visible in ULF Raman spectra interfering with measured Raman bandsBragGrate™ Bandpass Filter (BPF) has the linewidth ~5 cm-1 FWHM)and, thus, removes laser noise down to 5 cm-1 with suppression up to -70 dB BPF is a reflecting VBG which diffraction efficiency and other parameters are optimized for best noise removal close to the laser lineWavelength Range 400 nm to 2 µm. Standard wavelengths: 405, 488, 514, 532, 633, 785, 1064 nm. Any custom wavelength in the range can be fabricatedStandard BPF dimensions: 5×5×2 mm3 (785 nm filters are typically different in size)BPFs can be mounted in 1” or 0.5” mm round aluminum holders to be used with standard opto-mechanical mountsBPFs provide both spectral and spatial filtering as shown in figures below

Spectral filtering of laser light with BPF. Red line: spectrum of a 785 nm diode laser with ASE background. Blue line: BPF removes the ASE background in immediate vicinity of the laser line. LD light beam cleaned with BPF enabled ULF Raman measurement down to 5 cm-1

Spatial filtering of laser light with BPF. Left panel: far field image of HeNe laser beam profile without cleaning. Right panel: HeNe laser beam profile after spatial filtering with BPF. At the same time the laser is spectrally cleaned to -70 dB as close as 5 cm-1 form the laser line


Examples: ULF Raman measurements of L-CystineExamples: ULF Raman measurements of L-Cystine

data courtesy of Horiba Jobin Yvon

Ultra-low frequency measurements of L-Cystine at 4 different wavelengths: 488, 532, 633 nm (left) and 785 nm (right)


Examples: ULF Raman spectrum of SiGe superlatticeExamples: ULF Raman spectrum of SiGe superlattice

0

10 000

20 000

30 000

40 000

50 000

60 000

-500 0 500Raman Shift (cm -1 )

0

10 000

20 000

30 000

40 000

50 000

60 000

-500 0 500Raman Shift (cm -1 )

0

1 000

2 000

3 000

-80 -60 -40 -20 0 20 40 60 80Raman Shift (cm -1 )

-83

-77 -74 -6

7 -64 -5

7 -54

-47

-44

-37

-34

-27

-24 -1

7 -1

4

-7

7

14 1

7

23

27

34

37

44 47

53

57

64

67

73

77

83

86

0

1 000

2 000

3 000

-80 -60 -40 -20 0 20 40 60 80Raman Shift (cm -1 )

-83

-77 -74 -6

7 -64 -5

7 -54

-47

-44

-37

-34

-27

-24 -1

7 -1

4

-7

7

14 1

7

23

27

34

37

44 47

53

57

64

67

73

77

83

86

data courtesy of : P. H. Tan, State Key Laboratory for SL and Microstr., Institute of Semiconductors, Beijing, P. R. China; K. Brunner, University Wuerzburg, Germany


Examples: ULF Raman spectra at 5 cm-1 and belowExamples: ULF Raman spectra at 5 cm-1 and below

Data courtesy of P. H. Tan, State Key Laboratory for SL and Microstr., Institute of Semiconductors, Beijing, P. R. China;


Data courtesy of HORIBA Jobin Yvon SAS; measured with LabRAM HR Evolution

ULF Raman spectrum of several layers of MoS2 flakes

BragGrate™ Raman filters in work: selected publicationsBragGrate™ Raman filters in work: selected publicationsGlebov et al., "Volume Bragg gratings as ultra-narrow and multiband optical filters", Proc. SPIE Vol. 8428, 84280C (2012), invitedTan et al., “The shear mode of multilayer graphene,” Nature, Materials 11, 294–300 (2012).Ferrari et al., “Raman Spectroscopy as a versatile tool for studying the properties of graphene,” Nature, Nanotechnology 8, 236-246 (2013)Chen et at., “Electronic Raman Scattering On Individual Semiconducting Single Walled Carbon Nanotubes,” Nature, Sci. Reports 4, No. 5969 (2014)Ge et al., “Coherent Longitudinal Acoustic Phonon Approaching THz Frequency in Multilayer MoS2,” Nature, Sci. Reports 4, No. 5722 (2014)Cong et al., “Enhanced ultra-low-frequency interlayer shear modes in folded graphene layers,” Nature, Communications 5, No. 4709 (2014)Wu et al., “Resonant Raman spectroscopy of twisted multilayer graphene,” Nature, Communications 5, No. 5309 (2014)Wojcieszak et at., “Origin of the variability of the mechanical properties of silk fibers: Order/crystallinity along silkworm and spider fibers,” J. Raman Spectroscopy 45, Issue 10, pages 895–902, (2014)Reymond-Laruinaz et al., “Growth and size distribution of Au nanoparticles in annealed Au/TiO2 thin films,” Thin Solid Films 553, (2014)Tan et al., “Ultralow-frequency shear modes of 2-4 layer graphene observed in scroll structures at edges,” Phys. Rev. B 89, 235404 (2014)Du et al., “Soft vibrational mode associated with incommensurate orbital order in multiferroic CaMn7O12,” Phys. Rev. B 90, 104414 (2014)Chang et al., “Imaging molecular crystal polymorphs and their polycrystalline microstructures in situ by ultralow-frequency Raman spectroscopy,” Chem. Commun. 50, pages 12973-12976, (2014)Alamendia et at., “Protective ability index measurement through Raman quantification imaging to diagnose the conservation state of weathering steel structures,” J. Raman Spectroscopy (2014)Hehlen et al., “Soft-mode dynamics in micrograin and nanograin ceramics of strontium titanate observed by hyper-Raman scattering”, Phys. Rev. B 87, 014303 (2013)Zeng et al., “Low-frequency Raman modes and electronic excitations in atomically thin MoS2 films,” Phys. Rev. B 86, 241301(R) (2012)Ibanez et al., “Raman scattering by folded acoustic phonons in InGaN/GaN superlattices,” J. Raman Spectrosc. 43, 237-240 (2012)Zhang et al., “Raman spectroscopy of shear and layer breathing modes in multilayer MoS2,” Phys. Rev. B 87, 115413 (2013)Saviot et al., “Quasi-free nanoparticle vibrations in a highly-compressed ZrO2 nanopowder”, J. Phys. Chem. C 116, 22043 (2012) Tsurumi et al., “Evaluation of the interlayer interactions of few layers of graphene”, Chem. Phys. Letters 557, 114–117 (2013) Boukhicha et al., “Anharmonic phonons in few-layer MoS2: Raman spectroscopy of ultralow energy compression and shear modes,” Phys. Rev. B 87, 195316 (2013) Crespo-Monteiro et al., “One-step microstructuring of TiO2 and Ag-TiO2 films by continuous wave laser processing in the UV and visible ranges”, J. Phys. Chem. C 116, 26857 (2012)Zhao et al., “Interlayer Breathing and Shear Modes in Few-Trilayer MoS2 and WSe2,” Nano Lett. 13, 1007−1015 (2013)Schidt et al., “Moganite detection in silica rocks using Raman and infrared spectroscopy,” European J. Mineralogy 25, 797-805 (2013) Saviot et al., “THz nanocrystal acoustic vibrations from ZrO2 3D supercrystals,“J. Mater. Chem. C, 8108-8116 (2013)Rapaport et al., "Very Low Frequency Stokes and Anti-Stokes Raman Spectra Accessible with a Single Multichannel Spectrograph and Volume Bragg Grating Optical Filters," XXII ICORS, AIP Conference Proceedings, Volume 1267, pp. 808-809 (2010). Tsurumi, A., Naito, Y., Iwata, K., “Construction of Multichannel Low-Frequency Raman Microspectrometer of Spectral Coverage to 20 cm-1 with Gratings Formed in Glass Plates”, XXII ICORS, AIP Conference Proceedings, Volume 1267, pp. 792-793 (2010).


braggrate™ raman filters -...

Documents