Publications by authors named "Mohammad U Piracha"

A fiber-based chirped-pulse amplification (CPA) system with an active feedback loop for pulse shaping is experimentally demonstrated. A spectral processor is used in conjunction with a frequency-resolved optical gating measurement to produce high-quality pulses. Spectral phase and intensity shaping are utilized to generate a clean, high-contrast, transform-limited pulse with 15 dB pedestal suppression in the pulse wing tails, resulting in a five time increase in peak power of the CPA system.

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We report on infrared supercontinuum generation extending over more than one octave of bandwidth, from 850 nm to 2.35 μm, produced in a single spatial mode from a robust, compact, composite chalcogenide glass nanotaper. A picosecond laser at 1.

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Self-phase modulation in fiber amplifiers can significantly degrade the quality of compressed pulses in chirped pulse amplification systems. Parabolic pulses with linear frequency chirp are suitable for suppressing nonlinearities, and to achieve high peak power pulses after compression. In this paper, we present an active time domain technique to generate parabolic pulses for chirped pulse amplification applications.

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A lidar system based on the coherent detection of oppositely chirped pulses generated using a 20 MHz mode locked laser and chirped fiber Bragg gratings is presented. Sub millimeter resolution ranging is performed with > 25 dB signal to noise ratio. Simultaneous, range and Doppler velocity measurements are experimentally demonstrated using a target moving at > 330 km/h inside the laboratory.

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A lidar technique employing temporally stretched, frequency chirped pulses from a 20 MHz mode locked laser is presented. Sub-millimeter resolution at a target range of 10.1 km (in fiber) is observed.

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A 10.287 GHz optoelectronic oscillator is experimentally demonstrated that uses a 1000 finesse Fabry-Perot etalon as the mode selector instead of an rf filter. The results are compared with a standard optoelectronic loop with an rf filter.

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