Highly programmable wavelength selective switch based on liquid crystal on silicon switching elements

Baxter, G. W.; Frisken, Steve; Abakoumov, D.; Zhou, Hao; Clarke, Ian; Bartos, A.; Poole, Stephen

doi:10.1109/ofc.2006.215365

Cited by 177 publications

(89 citation statements)

References 3 publications

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“…Phase-only nematic LCOS devices are now becoming the dominant optical switch technology in reconfigurable add-drop multiplexers (ROADMs). [102][103][104][105] One of the best performances for ROADMs was demonstrated by Robertson et al 19 recently and implements a multifunctional 139 wavelength selective switch (WSS) based on a phase-only nematic LCOS device with 27.6 dB of insertion loss and 219.4 dB of the worst-case crosstalk for a channel spacing of 100 and 200 GHz. These devices offer better control of the optical wavefronts and more flexibility than MEMS (micro electro mechanical systems) devices.…”

Section: Algorithms Of Hologram Generation For Phase-only Lcos Devicementioning

confidence: 99%

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

2014

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This paper describes the fundamentals of phase-only liquid crystal on silicon (LCOS) technology, which have not been previously discussed in detail. This technology is widely utilized in high efficiency applications for real-time holography and diffractive optics. The paper begins with a brief introduction on the developmental trajectory of phase-only LCOS technology, followed by the correct selection of liquid crystal (LC) materials and corresponding electro-optic effects in such devices. Attention is focused on the essential requirements of the physical aspects of the LC layer as well as the indispensable parameters for the response time of the device. Furthermore, the basic functionalities embedded in the complementary metal oxide semiconductor (CMOS) silicon backplane for phase-only LCOS devices are illustrated, including two typical addressing schemes. Finally, the application of phase-only LCOS devices in real-time holography will be introduced in association with the use of cutting-edge computer-generated holograms. The architecture of LCOS devices is similar to conventional LC devices except that a silicon backplane constitutes one of the substrates (Figure 1). The silicon CMOS backplane consists of the electronic circuitry that is buried underneath pixel arrays to provide a high 'fill factor'. The pixels are aluminum mirrors deposited on the surface of the silicon backplane. The incident light is transmitted through the LC layer with almost zero absorption. The integration of high-performance driving circuitry allows the applied voltage to be changed on each pixel, thereby controlling the phase retardation of the incident wavefront across the device. Currently, there are two types of light modulation using LCOS devices, amplitude modulation and phase modulation. In the former case, the amplitude of the light signal is modulated 6,7 by varying the linear polarzation direction of the incident light passing through a linear polarizer, the same principle used in a standard LC television. In the latter case, the phase delay is accomplished by electrically adjusting the optical refractive index along the light path, which is possible because of the non-zero birefringence of the LC materials in use but should be carefully characterized. [8][9][10][11][12][13] In a phase-only LCOS SLM modulator, no light absorption by polarizers or other light-absorbing components will occur, such that the maximum light efficiency can be expected.Currently, most of the conventional LC devices are not able to efficiently modulate the phase of an incident wavefront. For instance, the LC device structure using thin film transistors is not suitable for phase modulation because an appropriate electro-optic effect has not been used (see the section on 'Twisted nematic (TN) configuration' and the section on 'VAN configuration' for details). Moreover, the pixels of this type of device are too large to provide acceptably large diffraction angles. In addition, the pixel circuitry and connection tracks are in the light path such that the ...

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Section: Algorithms Of Hologram Generation For Phase-only Lcos Devicementioning

confidence: 99%

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

2014

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“…Frequency slot-based, gridless switching can be real-ized with bandwidth-variable wavelength cross-connects and reconfigurable optical add drop multiplexers (BVWXCs/ROADMs) that employ gridless WSSs based on, for example, a liquid crystal on silicon (LCoS) spatial light modulator [39]. The LCoS consists of a large number of two-dimensionally arranged pixels.…”

Section: Gridless Wsssmentioning

confidence: 99%

Recent Advances in Elastic Optical Networking

Tanaka

Jinno

2014

IEICE Trans. Commun.

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SUMMARYMany detailed studies ranging from networking to hardware as well as standardization activities over the last few years have advanced the performance of the elastic optical network. Thanks to these intensive works, the elastic optical network has been becoming feasible. This paper reviews the recent advances in the elastic optical network from the aspects of networking technology and hardware design. For the former, we focus on the efficient elastic network design technology related to routing and spectrum assignment (RSA) of elastic optical paths including network optimization or standardization activities, and for the latter, two key enabling technologies are discussed: elastic transponders/regenerators and gridless optical switches. Making closely-dependent networking and hardware technologies work synergistically is the key factor in implementing truly effective elastic optical networks. key words: elastic optical network, network design, routing and spectrum assignment, elastic transponder

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“…All these techniques however, require manual tuning of some physical parameters of the cavity. Recently, fully programmable phase and amplitude filters [3] have become available commercially and are already extensively used in telecommunications applications [4]. The use of such filters, when placed inside a laser cavity, has the potential to allow the operation of lasers that exhibit pulse characteristics that can be controlled purely through software control [5].…”

Section: Introductionmentioning

confidence: 99%