Analytical study on arbitrary waveform generation by MEMS micro mirror arrays.

We provide analytical modeling and the detailed procedure that is used in recently proposed arbitrary waveform generation technique by using MEMS digital micro-mirror arrays. We estimate the achievable temporal resolution, repetition rate, modulation index and the rise/fall times of the final waveform as figure of merit in the proposed systems. We show that reducing the diffraction limit via increasing the ratio of beam size to lens focal length (>0.075) and the spatial modulation down to single mirror pitch size (10.8μm), waveforms up to 18GHz repetition rates with >90% modulation index and <100ps rise times are achievable. Theoretical calculations are compared with experimental generation of 120MHz square waves and 160MHz sawtooth waves and obtained good agreement

Analytical study on arbitrary waveform generation by MEMS micro mirror arrays.

We provide analytical modeling and the detailed procedure that is used in recently proposed arbitrary waveform generation technique by using MEMS digital micro-mirror arrays. We estimate the achievable temporal resolution, repetition rate, modulation index and the rise/fall times of the final waveform as figure of merit in the proposed systems. We show that reducing the diffraction limit via increasing the ratio of beam size to lens focal length (>0.075) and the spatial modulation down to single mirror pitch size (10.8μm), waveforms up to 18GHz repetition rates with >90% modulation index and <100ps rise times are achievable. Theoretical calculations are compared with experimental generation of 120MHz square waves and 160MHz sawtooth waves and obtained good agreement

Silicon-on-sapphire waveguides design for mid-IR evanescent field absorption gas sensors

Major trace gases have absorption lines in mid-IR. We propose silicon-on-sapphire waveguides at mid-IR for gas sensing based on evanescent field absorption. This can provide a general platform for multipurpose sensing of different types of gases in a reusable fashion. Three types of waveguides (strip, rib and slot) are investigated on their geometrical dependence of evanescent-field ratio (EFR) and propagation loss to serve as the proposed gas sensor. Slot waveguide provides the highest EFR (>25%) in mid-IR with moderate dimension, but its fabrication can be more challenging and its high loss (~10 dB/cm) impairs the sensing resolution and necessitates higher input power in longer waveguides. Strip and rib waveguides can achieve similar EFR with smaller dimensions. We analyze the detection of CO2 in atmosphere based on its mid-IR absorption peak at ~4.23 µm as a case study. Numerical analysis based on up-to-date commercial mid-IR detector parameters shows that a resolution of 2 ppm, 5 ppm and 50 ppm can be achieved in cooled InSb, room-temperature HgCdTe and room-temperature PbSe detectors respectively by using 1 cm waveguides. Effect of waveguide loss also has been investigated

Discrete parametric band conversion in silicon for mid-infrared applications

Silicon photonics has great potential for mid-wave-infrared applications. The dispersion of waveguide can be manipulated by waveguide dimension and cladding materials. Simulation shows that < 3 mu m wide conversion can be achieved by tuning the pump wavelength. (C) 2010 Optical Society of Americ

Discrete parametric band conversion in silicon for mid-infrared applications

Silicon photonics has great potential for mid-wave-infrared applications. The dispersion of waveguide can be manipulated by waveguide dimension and cladding materials. Simulation shows that < 3 mu m wide conversion can be achieved by tuning the pump wavelength. (C) 2010 Optical Society of Americ

Stability analysis of second order pulsed Raman laser in dispersion managed systems

Wavelength tunable synchronous pulse sources are highly desirable for spectroscopy and optical diagnostics. The common method to generate short pulses in the fiber is the use of nonlinear induced spectral broadening which result in soliton shaping in anomalous dispersion regime. However, to generate ultra-short pulses, broadband gain mechanism is also required. In recent years, Raman fiber lasers have retrieved strong interest due to their capability of serving as pump sources in gain-flattened amplifiers for optical communication systems. The fixed-wavelength Raman lasers have been widely studied in the last years, but recently, much focus has been on the multi wavelength tunable Raman fiber lasers which generate output Stokes pulses in a broad wavelength range by so called cascaded stimulated Raman scattering. In this paper we investigate synchronous 1(st) and 2(nd) order pulsed Raman lasers that can achieve frequency spacing of up to 1000cm(-1) that is highly desired for CARS microscopy. In particular, analytical and numerical analysis of pulsed stability derived for Raman lasers by using dispersion managed telecom fibers and pumped by 1530nm fiber lasers. We show the evolution of the 1st and 2nd order Stokes signals at the output for different pump power and SMF length (determines the net anomalous dispersion) combinations. We investigated the stability of dispersion managed synchronous Raman laser up to second order both analytically and numerically. The results show that the stable 2(nd) order Raman Stokes pulses with 0.04W to 0.1W peak power and 2ps to 3.5ps pulse width can be achieved in dispersion managed system