OECC/ACOFT Sydney, Australia 8-10 July ---

PVJapan Tokyo, Japan 30 July-1 August P-339 OPTICS + PHOTONICS San Diego, California 10-14 August 527

InterOpto08 Chiba, Japan 10-12 September 53

ECOC Brussels, Belgium 22-24 September 212

Photonics Korea Gwangju, Korea 23-25 September TBA*

COLCOM Bogotá, Colombia 25-26 September TBA*

LED Japan Tokyo, Japan 16-17 October TBA*

MILCOM San Diego, California 17-19 November 1839

4

WDM_Equipment type which can hold WDM multiplexer, CWDM multiplexers or ROADMs

The new graphical user interface supports both a global set of equipment as well as a project specific set of equipment. The latter can be created from the former using a simple dialog. The Fiber Library allows predefined fiber types to be specified for the network links to facilitate realistic link designs. Custom fiber types can also be added to the Fiber Library. The network design now supports ETSI, ANSI or user-defined transmission rates.

Once the network design is completed, there are several available options for visualizing the results. Some of the options are:

The user can view the designed ring/mesh network as a highlighted portion of the overall network.

The user can see individual ring details like route of the ring, demands carried by the ring, and how each wave length is routed in a WDM ring.

The user can also see the working path, the protection path and the restoration path for each traffic demand in the network.

The new interface also provides facilities for annotating the network graph so that more information can be expressed visually in the design. MetroWAND™ 4.0 is a major redesign of our network-planning tool. The new GUI is more intuitive, more flexible, more powerful and will ultimately significantly improve the user’s experience with the tool.

JULY-DECEMBER 2008

TH

E S

OU

RC

E F

OR

PH

OT

ON

IC &

NE

TW

OR

K D

ES

IGN

SO

FT

WA

RE

Including Stress Effects in an Optical Simulation

OptSim™ Simulation of 40- and 100-Gbps Polarization-Multiplexed QPSK Systems

High-density optical systems operating at 40 and 100 Gbps require advanced transmission schemes for accurate delivery of data over long reaches. Towards this end, coherent phase modulation technologies coupled with polarization multiplexing have been developed. In one such approach, polarization-mul-tiplexed quadrature-phase-shift-keying (PM-QPSK), four data signals are used to generate a single opti-cal signal, where each of its polarizations supports a QPSK-modulated data-signal pair. As an example of the utility of this approach, its high spectral efficiency is expected to provide a solution for implementing 40-Gbps-per-wavelength transmission in existing 10-Gbps architectures [1].

Typically, the receivers necessary for demodulat-ing a PM-QPSK signal must be able to extract the relevant polarization information from the signal, as

1

Stress can be an important factor in the performance of many types of devices. For example, it can induce birefringence in optical fibers, which can change the differential group delay (DGD) between polarization modes, and affect the behavior of fiber sensors or polarization-maintaining (PM) fiber ampli-fiers. These stresses can be residual from the fiber fabrication process and can either be introduced intentionally or naturally

occurring. Stress can also be generated or controlled thermally in waveguide devices comprised of materials with different expansion coefficients.

To address such device applications, the Multi-Physics capabilities of RSoft Design Group’s device tool suite have been expanded to include stress-optic effects, in addition

continued on page 2

continued on page 2

MetroWAND™ 4.0 arrives with a NEW look! continued from page 3

Trade show events calendar – 2008 SECOND HALF

SHOW LOCATION DATE BOOTH #

network is being planned can also be imported into the design to improve the visualization of the network topology.

In MetroWAND™, the functional models of real life pieces of equip-ment are arranged in an equipment library. The software equipment model is in accordance with TMF 814 (Tele Management Forum) standards. The list of equipment holders like bay, shelf, slots and circuit packs are modeled per TMF 814. Vendors can fully customize and store their equipment models in the equipment library.

The equipment library supports two types of equipment holders:

MSPP_ Equipment type which can hold SONET ADMs, SDH ADMs, Multi Service Provisioning Platforms (MSPP) nodes or Digital Cross Connects

– 2008 SECOND HALF

UNITED STATES Corporate headquarters

RSoft Design Group, Inc.400 Executive Boulevard, Ste. 100Ossining, NY 10562, USA

PHONE: 914.923.2164 E-MAIL: info@rsoftdesign.com WEB: www.rsoftdesign.com

JAPANRSoft Design Group Japan KKMatsura Building 2F, 1-9-6 Shiba Minato-ku, Tokyo, 105-0014 Japan

PHONE: + 81.3.5484.6670 EMAIL: info@rsoftdesign.co.jp

EUROPERSoft Design UK, Ltd.11 Swinborne DriveSpringwood Industrial EstateBraintree, Essex CM7 2YP

PHONE: 44 (0)1376 528556 EMAIL: info@rsoftdesign.co.uk

*Please check our website for the latest trade show information.

Figure 1: Strain calculation for a silicon ridge waveguide buried in SiO2. Shown here are the x (left) and y (middle) components of the strain profile, and the corresponding index perturbation (right).

Figure 1: OptSim™ topology for simulation of a PM-QPSK WDM system with a DSP-based phase- and polarization-diversity receiver.

VOLUME 7 NUMBER 2

and DiffractMOD, which uses Rigorous Coupled Wave Analysis (RCWA), can now easily model a variety of solar cell geometries. Structures with both periodic diffractive optical elements as well as non-periodic diffuse interfaces can be modeled.

The new utility simplifies common tasks associated with solar cell design. Users must first define the solar cell geometry in RSoft’s user-friendly CAD environment as well as material prop-erties such as a frequency-dependant complex refractive index that includes absorption. This material information can be easily input from RSoft’s new material library or from user-defined data sets. Once the structure has been defined, users can assign collection efficiencies and the incident spectrum, which is the solar spectrum by default. Then, all of the pertinent device per-formance information such as J-V curves, quantum efficiency vs. wavelength, shadowing, and overall cell efficiency are rigorously computed. Additionally, scanning and optimization of any geo-metric, material, or solar cell design variables are possible via RSoft’s scanning and optimization tool MOST™.

2 3

well as provide a phase-locked local oscillator. However, recent advances have demonstrated that the use of digital signal pro-cessing (DSP) can dramatically simplify the receiver design [1]-[3]. In a DSP-based coherent receiver, the local oscillator need not be phase-locked to the signal, nor is complicated polarization handling required. Instead, receiver circuitry is used to convert the received PM-QPSK signal into electrical signals representing the in-phase and quadrature portions of each optical polarization. DSP circuitry is then used to accu-rately extract the original data, while simultaneously compen-sating for linear impairments such as dispersion.

OptSim™ now includes models that allow for the accurate sim-ulation of these DSP-based phase- and polarization-diversity receiver technologies. These models include a filtered splitter/combiner for generating the optical signals to be detected at each photodiode, an electronic dispersion compensation module, a DSP module that implements a constant modu-lus algorithm (CMA) for polarization de multiplexing [3], a Viterbi-Viterbi algorithm for phase estimation [3], and error counting.

As Fig. 1 depicts, these models can be used to implement a PM-QPSK coherent receiver applicable to WDM systems with data rates over 100-Gbps per wavelength. In this example, the new OptSim™ models have been used in a 36-channel PM-QPSK WDM system. Each transmitter generates a single PM-QPSK signal from four 27.9-Gbps data channels (overhead is included to account for forward error correction). After transmission over 1800 km of fiber (without in-line dispersion compensation), a DSP-based coherent receiver is

used to determine the bit error rate (BER) of one of the chan-nels. The plot inset of Fig. 1 displays the pre-FEC BER as a function of span loss. These pre-FEC values on the order of 10-3 demonstrate the suitability of this approach for long distance transmission.

With its new models for DSP-based PM-QPSK receivers, OptSim™ is ideal for the accurate simulation of state-of-the-art coherent systems. Please contact RSoft Design Group (info@rsoftdesign.com) for additional details.

References

[1] C. Laperle, B. Villenueve, Z. Zhang, D. McGhan, H. Sun, and M. O’Sullivan, “WDM performance and PMD tolerance of a coherent 40-Gbit/s dual-polarization QPSK transceiver,” Journal of Lightwave Technology, vol. 26, no. 1, pp. 168-175, January 2008.

[2] S. J. Savory, A. D. Stewart, S. Wood, G. Gavioli, M. G. Taylor, R. I. Killey, and P. Bayvel, “Digital equalisation of 40Gbit/s per wavelength transmission over 2480km of standard fibre without optical dispersion compensation,” in Proceedings of ECOC 2006, Cannes, France, paper Th2.5.5, September 2006.

[3] J. Renaudier, G. Charlet, M. Salsi, O. B. Pardo, H. Mardoyan, P. Tran, and S. Bigo, “Linear fiber impairments mitigation of 40-Gbit/s polarization-multiplexed QPSK by digital process-ing in a coherent receiver,” Journal of Lightwave Technology, vol. 26, no. 1, pp. 36-42, January 2008.

to the long-standing electro-optic and thermo-optic features. Furthermore, all the material parameters for these physical processes can be found in RSoft’s new Material Library. This allows the user define a specific material within a region of space, rather than just the index. All properties of that material are then available for calculation.

As would be expected, any of the simulation engines in the device tool suite, such as BeamPROP™, FullWAVE™, or FemSIM™ can make use of these multi-physics capa-bilities, permitting the analysis of a wide variety of device applications. Additionally, scanning and optimization of design variables can be achieved through the use of MOST™. Furthermore, system applications can benefit from these new capabilities through the close integra-tion between OptSim™ and device tools.

Including Stress Effects in an Optical Simulation continued from page 1

OptSim™ Simulation of 40- and 100-Gbps Polarization-Multiplexed QPSK Systems continued from page 1

THE SOURCE FOR PHOTONIC AND NETWORK DESIGN SOFTWARE THE SOURCE FOR PHOTONIC AND NETWORK DESIGN SOFTWARE

Solar cells have the potential to be a dominant player in the renewable energy industry over the coming decades. Thin-film solar cells are particularly promising since they can be cost effectively mass produced. However, the major drawback of these types of cells is a relatively low efficiency since a large portion of solar energy is turned into heat rather than electricity.

One way to reduce this heat loss and increase the conver-sion to electricity is to utilize multi-layer structures in which the band gap of each layer is tuned to a different portion of the solar spectrum. In addition, more light can be trapped and

With a variety of equipment and technology, optical network plan-ning is getting more complex day by day. In order to achieve ef-ficiency in optical planning, visualization of the network build out and ‘what if’ analysis is a must. RSoft Design Group’s popular network planning tool MetroWAND™, has a new graphical user interface (GUI) that allows network planners to create and design an optical network in a systematic way.

The software supports both the ring and the mesh design engines. The ring design optimizes the placement of rings, the number of

rings, as well as routing of traffic in different ring technologies like UPSR/SNCP, BLSR/MSSP and WDM rings. The mesh network design supports various routing schemes and restoration capacity planning. The new GUI allows users to create the network on the canvas in a more efficient way than was possible in previous ver-sions of MetroWAND™. The user can customize the visual aspects of the network design in several ways: As shown in Figure 1, the data associated with all links can be edited from a common dialog box without the need to go to each link(node) thus saving time when creating a network. A map of the geographic area over which the

MetroWAND™ 4.0 arrives with a NEW look!

absorbed within the cell by using textured layer interfaces. Light incident on these inter-faces will diffract in random directions, effectively maximiz-ing the path-length of light in the device and increasing the absorption.

Optical design software is necessary to quickly character-ize multiple designs in order

to produce a desired optimal design RSoft has developed a new Solar Cell Utility for use in conjunction with existing pas-sive device simulation tools. Users of RSoft’s FullWAVE™, which employs the Finite-Difference Time-Domain (FDTD) method,

continued on page 4

Figure 2: Mode calculations for the silicon-SiO2 waveguide with (right) and without (left) strain. Note that the effective index of the mode has changed by ~0.0016.

Figure 1: Solar Cell structure com-prised of multiple layers, each with a different absorption spectra.

Figure 2: A typical J-V curve accounting for individual layer collection efficiencies and shadowing.

Texturedabsorbinglayers

and DiffractMOD, which uses Rigorous Coupled Wave Analysis (RCWA), can now easily model a variety of solar cell geometries. Structures with both periodic diffractive optical elements as well as non-periodic diffuse interfaces can be modeled.

The new utility simplifies common tasks associated with solar cell design. Users must first define the solar cell geometry in RSoft’s user-friendly CAD environment as well as material prop-erties such as a frequency-dependant complex refractive index that includes absorption. This material information can be easily input from RSoft’s new material library or from user-defined data sets. Once the structure has been defined, users can assign collection efficiencies and the incident spectrum, which is the solar spectrum by default. Then, all of the pertinent device per-formance information such as J-V curves, quantum efficiency vs. wavelength, shadowing, and overall cell efficiency are rigorously computed. Additionally, scanning and optimization of any geo-metric, material, or solar cell design variables are possible via RSoft’s scanning and optimization tool MOST™.

2 3

well as provide a phase-locked local oscillator. However, recent advances have demonstrated that the use of digital signal pro-cessing (DSP) can dramatically simplify the receiver design [1]-[3]. In a DSP-based coherent receiver, the local oscillator need not be phase-locked to the signal, nor is complicated polarization handling required. Instead, receiver circuitry is used to convert the received PM-QPSK signal into electrical signals representing the in-phase and quadrature portions of each optical polarization. DSP circuitry is then used to accu-rately extract the original data, while simultaneously compen-sating for linear impairments such as dispersion.

OptSim™ now includes models that allow for the accurate sim-ulation of these DSP-based phase- and polarization-diversity receiver technologies. These models include a filtered splitter/combiner for generating the optical signals to be detected at each photodiode, an electronic dispersion compensation module, a DSP module that implements a constant modu-lus algorithm (CMA) for polarization de multiplexing [3], a Viterbi-Viterbi algorithm for phase estimation [3], and error counting.

As Fig. 1 depicts, these models can be used to implement a PM-QPSK coherent receiver applicable to WDM systems with data rates over 100-Gbps per wavelength. In this example, the new OptSim™ models have been used in a 36-channel PM-QPSK WDM system. Each transmitter generates a single PM-QPSK signal from four 27.9-Gbps data channels (overhead is included to account for forward error correction). After transmission over 1800 km of fiber (without in-line dispersion compensation), a DSP-based coherent receiver is

used to determine the bit error rate (BER) of one of the chan-nels. The plot inset of Fig. 1 displays the pre-FEC BER as a function of span loss. These pre-FEC values on the order of 10-3 demonstrate the suitability of this approach for long distance transmission.

With its new models for DSP-based PM-QPSK receivers, OptSim™ is ideal for the accurate simulation of state-of-the-art coherent systems. Please contact RSoft Design Group (info@rsoftdesign.com) for additional details.

References

[1] C. Laperle, B. Villenueve, Z. Zhang, D. McGhan, H. Sun, and M. O’Sullivan, “WDM performance and PMD tolerance of a coherent 40-Gbit/s dual-polarization QPSK transceiver,” Journal of Lightwave Technology, vol. 26, no. 1, pp. 168-175, January 2008.

[2] S. J. Savory, A. D. Stewart, S. Wood, G. Gavioli, M. G. Taylor, R. I. Killey, and P. Bayvel, “Digital equalisation of 40Gbit/s per wavelength transmission over 2480km of standard fibre without optical dispersion compensation,” in Proceedings of ECOC 2006, Cannes, France, paper Th2.5.5, September 2006.

[3] J. Renaudier, G. Charlet, M. Salsi, O. B. Pardo, H. Mardoyan, P. Tran, and S. Bigo, “Linear fiber impairments mitigation of 40-Gbit/s polarization-multiplexed QPSK by digital process-ing in a coherent receiver,” Journal of Lightwave Technology, vol. 26, no. 1, pp. 36-42, January 2008.

to the long-standing electro-optic and thermo-optic features. Furthermore, all the material parameters for these physical processes can be found in RSoft’s new Material Library. This allows the user define a specific material within a region of space, rather than just the index. All properties of that material are then available for calculation.

As would be expected, any of the simulation engines in the device tool suite, such as BeamPROP™, FullWAVE™, or FemSIM™ can make use of these multi-physics capa-bilities, permitting the analysis of a wide variety of device applications. Additionally, scanning and optimization of design variables can be achieved through the use of MOST™. Furthermore, system applications can benefit from these new capabilities through the close integra-tion between OptSim™ and device tools.

Including Stress Effects in an Optical Simulation continued from page 1

OptSim™ Simulation of 40- and 100-Gbps Polarization-Multiplexed QPSK Systems continued from page 1

THE SOURCE FOR PHOTONIC AND NETWORK DESIGN SOFTWARE THE SOURCE FOR PHOTONIC AND NETWORK DESIGN SOFTWARE

Solar cells have the potential to be a dominant player in the renewable energy industry over the coming decades. Thin-film solar cells are particularly promising since they can be cost effectively mass produced. However, the major drawback of these types of cells is a relatively low efficiency since a large portion of solar energy is turned into heat rather than electricity.

One way to reduce this heat loss and increase the conver-sion to electricity is to utilize multi-layer structures in which the band gap of each layer is tuned to a different portion of the solar spectrum. In addition, more light can be trapped and

With a variety of equipment and technology, optical network plan-ning is getting more complex day by day. In order to achieve ef-ficiency in optical planning, visualization of the network build out and ‘what if’ analysis is a must. RSoft Design Group’s popular network planning tool MetroWAND™, has a new graphical user interface (GUI) that allows network planners to create and design an optical network in a systematic way.

The software supports both the ring and the mesh design engines. The ring design optimizes the placement of rings, the number of

rings, as well as routing of traffic in different ring technologies like UPSR/SNCP, BLSR/MSSP and WDM rings. The mesh network design supports various routing schemes and restoration capacity planning. The new GUI allows users to create the network on the canvas in a more efficient way than was possible in previous ver-sions of MetroWAND™. The user can customize the visual aspects of the network design in several ways: As shown in Figure 1, the data associated with all links can be edited from a common dialog box without the need to go to each link(node) thus saving time when creating a network. A map of the geographic area over which the

MetroWAND™ 4.0 arrives with a NEW look!

absorbed within the cell by using textured layer interfaces. Light incident on these inter-faces will diffract in random directions, effectively maximiz-ing the path-length of light in the device and increasing the absorption.

Optical design software is necessary to quickly character-ize multiple designs in order

to produce a desired optimal design RSoft has developed a new Solar Cell Utility for use in conjunction with existing pas-sive device simulation tools. Users of RSoft’s FullWAVE™, which employs the Finite-Difference Time-Domain (FDTD) method,

continued on page 4

Figure 2: Mode calculations for the silicon-SiO2 waveguide with (right) and without (left) strain. Note that the effective index of the mode has changed by ~0.0016.

Figure 1: Solar Cell structure com-prised of multiple layers, each with a different absorption spectra.

Figure 2: A typical J-V curve accounting for individual layer collection efficiencies and shadowing.

Texturedabsorbinglayers

OECC/ACOFT Sydney, Australia 8-10 July ---

PVJapan Tokyo, Japan 30 July-1 August P-339 OPTICS + PHOTONICS San Diego, California 10-14 August 527

InterOpto08 Chiba, Japan 10-12 September 53

ECOC Brussels, Belgium 22-24 September 212

Photonics Korea Gwangju, Korea 23-25 September TBA*

COLCOM Bogotá, Colombia 25-26 September TBA*

LED Japan Tokyo, Japan 16-17 October TBA*

MILCOM San Diego, California 17-19 November 1839

4

WDM_Equipment type which can hold WDM multiplexer, CWDM multiplexers or ROADMs

The new graphical user interface supports both a global set of equipment as well as a project specific set of equipment. The latter can be created from the former using a simple dialog. The Fiber Library allows predefined fiber types to be specified for the network links to facilitate realistic link designs. Custom fiber types can also be added to the Fiber Library. The network design now supports ETSI, ANSI or user-defined transmission rates.

Once the network design is completed, there are several available options for visualizing the results. Some of the options are:

The user can view the designed ring/mesh network as a highlighted portion of the overall network.

The user can see individual ring details like route of the ring, demands carried by the ring, and how each wave length is routed in a WDM ring.

The user can also see the working path, the protection path and the restoration path for each traffic demand in the network.

The new interface also provides facilities for annotating the network graph so that more information can be expressed visually in the design. MetroWAND™ 4.0 is a major redesign of our network-planning tool. The new GUI is more intuitive, more flexible, more powerful and will ultimately significantly improve the user’s experience with the tool.

JULY-DECEMBER 2008

TH

E S

OU

RC

E F

OR

PH

OT

ON

IC &

NE

TW

OR

K D

ES

IGN

SO

FT

WA

RE

Including Stress Effects in an Optical Simulation

OptSim™ Simulation of 40- and 100-Gbps Polarization-Multiplexed QPSK Systems

High-density optical systems operating at 40 and 100 Gbps require advanced transmission schemes for accurate delivery of data over long reaches. Towards this end, coherent phase modulation technologies coupled with polarization multiplexing have been developed. In one such approach, polarization-mul-tiplexed quadrature-phase-shift-keying (PM-QPSK), four data signals are used to generate a single opti-cal signal, where each of its polarizations supports a QPSK-modulated data-signal pair. As an example of the utility of this approach, its high spectral efficiency is expected to provide a solution for implementing 40-Gbps-per-wavelength transmission in existing 10-Gbps architectures [1].

Typically, the receivers necessary for demodulat-ing a PM-QPSK signal must be able to extract the relevant polarization information from the signal, as

1

Stress can be an important factor in the performance of many types of devices. For example, it can induce birefringence in optical fibers, which can change the differential group delay (DGD) between polarization modes, and affect the behavior of fiber sensors or polarization-maintaining (PM) fiber ampli-fiers. These stresses can be residual from the fiber fabrication process and can either be introduced intentionally or naturally

occurring. Stress can also be generated or controlled thermally in waveguide devices comprised of materials with different expansion coefficients.

To address such device applications, the Multi-Physics capabilities of RSoft Design Group’s device tool suite have been expanded to include stress-optic effects, in addition

continued on page 2

continued on page 2

MetroWAND™ 4.0 arrives with a NEW look! continued from page 3

Trade show events calendar – 2008 SECOND HALF

SHOW LOCATION DATE BOOTH #

network is being planned can also be imported into the design to improve the visualization of the network topology.

In MetroWAND™, the functional models of real life pieces of equip-ment are arranged in an equipment library. The software equipment model is in accordance with TMF 814 (Tele Management Forum) standards. The list of equipment holders like bay, shelf, slots and circuit packs are modeled per TMF 814. Vendors can fully customize and store their equipment models in the equipment library.

The equipment library supports two types of equipment holders:

MSPP_ Equipment type which can hold SONET ADMs, SDH ADMs, Multi Service Provisioning Platforms (MSPP) nodes or Digital Cross Connects

– 2008 SECOND HALF

UNITED STATES Corporate headquarters

RSoft Design Group, Inc.400 Executive Boulevard, Ste. 100Ossining, NY 10562, USA

PHONE: 914.923.2164 E-MAIL: info@rsoftdesign.com WEB: www.rsoftdesign.com

JAPANRSoft Design Group Japan KKMatsura Building 2F, 1-9-6 Shiba Minato-ku, Tokyo, 105-0014 Japan

PHONE: + 81.3.5484.6670 EMAIL: info@rsoftdesign.co.jp

EUROPERSoft Design UK, Ltd.11 Swinborne DriveSpringwood Industrial EstateBraintree, Essex CM7 2YP

PHONE: 44 (0)1376 528556 EMAIL: info@rsoftdesign.co.uk

*Please check our website for the latest trade show information.

Figure 1: Strain calculation for a silicon ridge waveguide buried in SiO2. Shown here are the x (left) and y (middle) components of the strain profile, and the corresponding index perturbation (right).

Figure 1: OptSim™ topology for simulation of a PM-QPSK WDM system with a DSP-based phase- and polarization-diversity receiver.

VOLUME 7 NUMBER 2