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Opto-VLSI-based tunable single-mode fiber laser
Xiao, Feng,Alameh, Kamal,Lee, TongTak The Optical Society 2009 Optics express Vol.17 No.21
<P>A new tunable fiber ring laser structure employing an Opto-VLSI processor and an erbium-doped fiber amplifier (EDFA) is reported. The Opto-VLSI processor is able to dynamically select and couple a waveband from the gain spectrum of the EDFA into a fiber ring, leading to a narrow-linewidth high-quality tunable laser output. Experimental results demonstrate a tunable fiber laser of linewidth 0.05 nm and centre wavelength tuned over the C-band with a 0.05 nm step. The measured side mode suppression ratio (SMSR) is greater than 35 dB and the laser output power uniformity is better than 0.25 dB. The laser output is very stable at room temperature.</P>
Tunable Multiwavelength Fiber Ring Lasers Based on an Opto-VLSI Processor
Feng Xiao,Alameh, Kamal,Yong Tak Lee IEEE 2011 IEEE photonics technology letters Vol.23 No.3
<P>We propose and experimentally demonstrate the principle of a tunable multiwavelength fiber ring laser based on the use of an opto-very-large-scale-integration (Opto-VLSI) processor in conjunction with an erbium-doped fiber amplifier and a semiconductor optical amplifier. Multiple wavelength channels within the gain range of the optical amplifiers can independently be generated, tuned and/or switched on/off, through applying appropriate phase holograms onto the Opto-VLSI processor. A tunable five-wavelength fiber ring laser of output power of around +6 dBm per channel and a sidemode suppression ratio (SMSR) greater than 30 dB is demonstrated. The tunable multiwavelength fiber lasers have excellent stability at room temperature.</P>
Multitap coherence-free photonic RF filter employing semiconductor optical amplifier
Zheng, Rong,Alameh, Kamal,Lee, Yong Tak,Wang, Zhenglin Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.5
<P>A novel multitap coherence-free photonic bandpass RF filter utilizing the cross-gain modulation property of the semiconductor optical amplifier to convert a coherent RF-modulated laser carrier to a low-coherence light that is sliced and delayed to realize a stable transversal RF filter. An 8-tap photonic RF bandpass filter operating at 2.25 GHz with more than 15 dB rejection is experimentally demonstrated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1103–1106, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22352</P>
Blue-Shifted Rogue Waves Generation in Normal Dispersion Fiber Laser
Afzal, Muhammad Imran,Alameh, Kamal,Yong Tak Lee IEEE 2015 IEEE photonics technology letters Vol.27 No.22
<P>In the presence of noise in normal dispersion fiber mode-locked lasers, dissipative resonance disappears, which leads to instability of spectral broadening and makes the asymptotic accumulation of energy impossible. We experimentally generate dissipative soliton molecules-like spectral peaks and rogue waves in the frequency domain in a self-mode-locked fiber laser. Due to noise in the initial triangular-shaped mode locked wave, these molecules are arranged in the form of lobes on the longer wavelength side, thus forming three virtual groups of soliton molecules. Further dissipative accumulation of power in the mode-locked wave ultimately leads to the formation of a blue-shifted group of three rogue waves, due to the effective fusion of adjacent soliton molecules. This is the first report of an experimental observation of blue-shifted and three rogue waves in a single experiment. The results have far reaching implications for experimentation with soliton collisions, optical rogue waves, and understanding of hydrodynamics.</P>
Ravindran, Sooraj,Datta, Arnab,Alameh, Kamal,Lee, Yong Tak Optical Society of America 2012 Optics express Vol.20 No.14
<P>We propose and analyse a GaAs-based optical switch having a ring resonator configuration which can switch optical telecommunication signals over the 1300 nm and 1500 nm bands, using bias assisted carrier injection as the switching mechanism. The switching is achieved through variation in the refractive index of the ring resonator produced by changing the injected carrier density through the application of bias voltage. Detail analysis of the switching characteristics reveals that the amount of switching depends on the refractive index change, which indeed is a strong function of injected carrier density and applied bias voltage. An isolation of 25 dB can be achieved during the ON state, while more than 40 dB isolation is realised during the OFF state. More importantly, our analysis shows that the proposed GaAs-based switch can operate over the 1300 nm and 1500 nm optical telecommunication bands, that are much farther from the bandgap of the GaAs material, without the need for 'conventional' Indium based ternary and quaternary semiconductor materials. It therefore extends the usable wavelength of GaAs based optoelectronic devices. Furthermore, we have presented detail calculations to quantify power-delay metric of the proposed device. The proposed optical switch maintains a smaller footprint as when compared to Mach-Zehnder Interferometer or Directional Coupler based switches therefore, making it suitable for large scale integration and implementing next generation optical interconnects, optical communication and computing.</P>
Tan, Chee Leong,Karar, Ayman,Alameh, Kamal,Lee, Yong Tak Optical Society of America 2013 Optics express Vol.21 No.2
<P>We propose and numerically demonstrate a high absorption hybrid-plasmonic-based metal semiconductor metal photodetector (MSM-PD) comprising metal nanogratings, a subwavelength slit and amorphous silicon or germanium embedded metal nanoparticles (NPs). Simulation results show that by optimizing the metal nanograting parameters, the subwavelength slit and the embedded metal NPs, a 1.3 order of magnitude increase in electric field is attained, leading to 28-fold absorption enhancement, in comparison with conventional MSM-PD structures. This is 3.5 times better than the absorption of surface plasmon polariton (SPP) based MSM-PD structures employing metal nanogratings and a subwavelength slit. This absorption enhancement is due to the ability of the embedded metal NPs to enhance their optical absorption and scattering properties through light-stimulated resonance aided by the conduction electrons of the NPs. (C)2013 Optical Society of America</P>
Tan, Chee Leong,Jang, Sung Jun,Song, Young Min,Alameh, Kamal,Lee, Yong Tak Springer 2014 NANOSCALE RESEARCH LETTERS Vol.9 No.1
<P>We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film's average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range.</P>