But for the LC-FBG- AOM, the wavelength spacing between the neighboring reflection peaks increased linearly and inversely with the acoustic frequency, and the extinction ratio of each peak relates to the acoustically induced strain. The simulation results of the GA-FBG- AOM and PS-FBG- AOM showed that the wavelength spacing between the primary reflection peak and the secondary reflection peak is proportional to the acoustic frequency, and the reflectivity of reflection peaks depends on the acoustically induced strains. Based on the model, the reflected spectra of these modulators were simulated under various acoustic frequencies and acoustically induced strains. Because of the accuracy and simplicity of the algorithm applied in this model, the modulation performances of these modulators can be acquired effectively and efficiently. Liu, Chao Pei, Li Li, Zhuoxuan Ning, Tigang Yu, Shaowei Kang, Zexinįourier mode coupling theory was first employed in the spectral analysis of several nonuniform fiber Bragg grating (FBG)-based acousto-optic modulators (NU-FBG- AOMs) with the effects of Gaussian-apodization (GA), phase shift (PS), and linear chirp (LC). Spectra analysis of nonuniform FBG-based acousto-optic modulator by using Fourier mode coupling theory. Detailed performance characteristics of a 267 nm acousto-optic modulator ( AOM) based pulse shaper are presented, Practical considerations for AOM based pulse shaping of ultra-broad bandwidth (sub-10 fs) amplified femtosecond pulse shaping are described, with particular attention paid to the effects of the RF frequency bandwidth and optical frequency bandwidth on the spatial dispersion of the output laser pulses. We present all the information necessary for construction and characterization of acousto optic pulse shapers, with a focus on ultraviolet wavelengths, Various radio-frequency drive configurations are presented to allow optimization via knowledgeable trade-off of design features. Mcgrane, Shawn D Moore, David S Greenfield, Margo T The energy of envelope of QML pulse train was up to 130 μJ with sub-nanosecond mode locked pulse of maximum 30-μJ energy.Ĭonstruction and characterization of ultraviolet acousto-optic based femtosecond pulse shapersĭOE Office of Scientific and Technical Information (OSTI.GOV) As a gain medium the Nd:YVO 4 crystal end pumped by 20 W laser diode was applied. We have designed the 3.69-m long Z-type resonator of the frequency matched to the RF frequency of AOM. The main aim of paper is to present novel type of lasers with acousto-optic modulation namely: AO-q-switched and mode locked (AO-QML) lasers. The achieved brightness of 10 17 W/m2/srd is comparable to the strongest technological Q-switched lasers of kW class of average power. The parameters of a simple AO-Q-switched Nd:YVO 4 laser (peak power up to 60 kW, pulse duration of 5-15 ns, repetition rate in the range 10-100 kHz, with average power above 5 W) are satisfactory for different application as follows: higher harmonic generation, pumping of 'eye-safe' OPOs etc. The short description of few DPSSLs developed in our group is presented in the following chapters of the paper. The critical review of application of AOMs in several types of diode pumped solid state lasers (DPSSL) is given. The main properties of acousto-optic modulators ( AOM) applied in laser technology are presented and discussed in the paper. Potentially, this new rapid-scanning optical delay device will improve the performance of high-speed Doppler OCT techniques.Īcousto-optic modulation in diode pumped solid state lasers The increased Doppler frequency shift by AOM also permits complete envelop demodulation without the compromise of reducing axial resolution if used with a resonant rapid-scanning optical delay, it will permit high-performance real-time OCT imaging. Experimental results show that the fluctuation of the measured Doppler frequency shift is less than +/-0.2% over 95% duty cycle of OCT imaging, thus allowing for enhanced signal-to-noise ratio of optical heterodyne detection. We report a new rapid-scanning optical delay device suitable for high-speed optical coherence tomography (OCT) in which an acousto-optic modulator ( AOM) is used to independently modulate the Doppler frequency shift of the reference light beam for optical heterodyne detection.
High-speed optical coherence tomography using fiberoptic acousto-optic phase modulation
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