Dispersion Trimming in a Reconfigurable Wavelength Selective Switch

Roelens, M.A.F.; Frisken, Steve; Bolger, J. A.; Abakoumov, D.; Baxter, G. W.; Poole, Stephen; Eggleton, B.J.

doi:10.1109/jlt.2007.912148

Cited by 237 publications

(105 citation statements)

References 7 publications

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“…In addition, the pulse shaper can only subtract power from the frequency components of the signal while manipulating its intensity, thereby potentially making the whole process extremely power inefficient. Fully-programmable amplitude and phase filters [29] are already commercially available and extensively used in telecommunications applications [30]. 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.…”

Section: Introductionmentioning

confidence: 99%

Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

2015

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We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various regimes of advanced waveform generation can be achieved, including ones featuring parabolic-, flat-top-and triangular-profiled pulses. An application of this approach using a flat-top spectral filter is shown to achieve the direct generation of high-quality sinc-shaped optical Nyquist pulses with a widely tunable bandwidth from the laser oscillator. We also present the operation of an ultrafast fibre laser in which conventional soliton, dispersion-managed soliton (stretched-pulse) and dissipative soliton mode-locking regimes can be selectively and reliably targeted by adaptively changing the dispersion profile and bandwidth programmed on an in-cavity programmable filter. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for achieving a high degree of control over the dynamics and output of mode-locked fibre lasers.

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Section: Introductionmentioning

confidence: 99%

Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

2015

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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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“…In recent years, liquid crystal on silicon (LCoS) [1,2] displays have become the most attractive micro-displays for all sorts of spatial light modulation (SLM) applications, as in diffractive optics [3], optical storage [4], optical metrology [5], reconfigurable interconnects [6,7], quantum optical computing [8], and wave shaper technology for optical signal processing and signal monitoring [9], thanks to their very high spatial resolution, very high light efficiency, and their phase-only modulation capability [10,11]. In this article, we focus on the characteristics of LCoS SLM for wavelength selective switch (WSS) systems used in reconfigurable optical add/drop multiplexers (ROADM) in wavelength division multiplexed (WDM) optical networks.…”

Section: Introductionmentioning

confidence: 99%

LCoS SLM Study and Its Application in Wavelength Selective Switch

et al. 2017

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Abstract:The Liquid-Crystal on Silicon (LCoS) spatial light modulator (SLM) has been used in wavelength selective switch (WSS) systems since the 1990s. However, most of the LCoS devices used for WSS systems have a pixel size larger than 6 µm. Although there are some negative physical effects related to smaller pixel sizes, the benefits of more available ports, larger spatial bandwidth, improved resolution, and the compactness of the whole system make the latest generation LCoS microdisplays highly appealing as the core component in WSS systems. In this review work, three specifications of the WSS system including response time, crosstalk and insertion loss, and optimization directions are discussed. With respect to response time, the achievements of liquid crystal material are briefly surveyed. For the study of crosstalk and insertion loss, related physical effects and their relation to the crosstalk or insertion loss are discussed in detail, preliminary experimental study for these physical effects based on a small pixel LCoS SLM device (GAEA device, provided by Holoeye, 3.74 µm pixel pitch, 10 megapixel resolution, telecom) is first performed, which helps with predicting and optimizing the performance of a WSS system with a small pixel size SLM. In the last part, the trend of LCoS devices for future WSS modules is discussed based on the performance of the GAEA device. Tradeoffs between multiple factors are illustrated. In this work, we present the first study, to our knowledge, of the possible application of a small pixel sized SLM as a switching component in a WSS system.

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Dispersion Trimming in a Reconfigurable Wavelength Selective Switch

Cited by 237 publications

References 7 publications

Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

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

LCoS SLM Study and Its Application in Wavelength Selective Switch

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