Search results for "Width"
showing 10 items of 690 documents
High-repetition rate acoustic-induced Q-switched all-fiber laser
2005
We report a high repetition rate actively Q switched all fiber laser. The acousto optic interaction controls the cou pling between co propagating core and cladding modes and is used to modulate the optical losses of the cavity, which permits to perform active Q-switching. Using 1.4 m of 300 ppm Er-doped fiber and a maximum pump power of 120 mW, we have obtained up to 1 W peak power pulses, with a pulse repetition rate that can be continuously varied from 1 Hz to 120 kHz and a pulse width that changes from 70 ns to 2.2 μs.
Chirped fibre Bragg gratings for phased-array antennas
1997
A variable delay line for phased-array antennas based on a chirped fibre Bragg grating is demonstrated. The time delay of a microwave modulating signal is modified by scanning in wavelength a chirped grating. In this initial experiment, time delay variations up to 556 ps have been achieved using a grating of 0.4 nm bandwidth and 6 cm length and modulating in the frequency range 390 MHz-5.20 GHz.
Broadband Fabry–Pérot Resonator From Zerodur for Laser Stabilisation Below 1KHZ Linewidth With < 100 HZ/S Drift and Reduced Sensitivity to Vibrati…
2015
Abstract Here we demonstrate the results of creating a two-mirror Fabry-Pérot resonator (FPR) that allows achieving the spectral width of a stabilised laser line below 1 kHz. It had low expansion Zerodur spacer and broadband high reflectance mirrors (99.85% in the range of 630 to 1140 nm). FPR was vertically mid-plane mounted for reduced sensitivity to vibrations and included in two shields inside a vacuum chamber to lower temperature fluctuations. Peltier element was used for temperature stabilisation at zero-expansion temperature. Pound-Drever-Hall (PDH) technique was applied. The signal from FPR was compared to ultra-stable signal (of about 1 Hz linewidth) to form a beat note signal. For…
Transform-limited spectral compression by self-phase modulation of amplitude-shaped pulses with negative chirp
2011
International audience; Spectral compression by self-phase modulation of amplitude- and phase-shaped pulses is demonstrated as superior compared to pulses that have only been phase shaped. We synthesize linearly negatively chirped parabolic pulses, which we send through a nonlinear photonic crystal fiber, in which self-phase modulation compresses the spectrum of the pulses to within 20% of the Fourier transform limit.
Mode locking of an all-fiber laser by acousto-optic superlattice modulation
2009
Active mode locking of an erbium-doped all-fiber laser with a Bragg-grating-based acousto-optic modulator is demonstrated. The fiber Bragg grating was acoustically modulated by a standing longitudinal elastic wave, which periodically modulates the sidebands at twice the acoustic frequency. The laser has a Fabry-Perot configuration in which cavity loss modulation is achieved by tuning the output fiber Bragg grating to one of the acoustically induced sidebands. Optical pulses at 9 MHz repetition rate, 120 mW peak power, and 780 ps temporal width were obtained. The output results to be stable and has a timing jitter below 40 ps. The measured linewidth, 2.8 pm, demonstrates that these pulses ar…
Interferometric Z-scan method for thermo-optical effect studies
2021
We demonstrated a new approach to measuring third-order nonlinear optical effects using an experimental setup incorporating both Z-scan and Mach-Zehnder interferometer methods. This method could be especially purposive for thermo-optical effect studies as it can simultaneously probe thermal gradient profile as well as absolute temperature changes induced by an optical beam. The experimental setup was tested using chloroform. Experimental measurements were carried out using 1064 nm Nd:YAG laser with 8 ns pulse width and 40 kHz pulse repetition rate. The measured nonlinear refractive index of chloroform was mainly induced by the thermo-optical effect. As thermo-optical response depends on bea…
Synthesis of optical pulses by use of similaritons.
2009
We propose and demonstrate experimentally a novel method for synthesizing chirp-free pulses of any desired temporal shape by means of chirp compensation and spectral filtering of optical Raman similaritons. The synthesized pulse shape is independent of the waveform, wavelength and energy of the initial pulses that are used for the similariton generation. Pulses are fully characterized by means of different techniques including cross-correlation and spectrum measurements, and the PICASO technique.
Relative phase locking of pulses in a passively mode-locked fiber laser
2003
In a passively mode-locked fiber ring laser, we report the experimental observation of relative phase locking of pulses in a wide variety of cases. Relative phase locking is observed in bunches of N pulses separated by more than 20 pulse widths as well as in close pulse pairs. In the latter case, the phase relationship between the two pulses is measured to be ±π/2, which is related to theoretical predictions formerly obtained from a Ginzburg-Landau distributed model. We have developed a simplified numerical model adapted to our laser, which keeps its essential features while significantly reducing the number of free parameters. The agreement with the experiment is excellent. © 2003 Optical …
Focusing of surface-acoustic-wave fields on (100) GaAs surfaces
2003
Focused surface-acoustic waves (SAWs) provide a way to reach intense acoustic fields for electro- and optoacoustic applications on semiconductors. We have investigated the focusing of SAWs by interdigital transducers (IDTs) deposited on (100)-oriented GaAs substrates. The focusing IDTs have curved fingers designed to account for the acoustic anisotropy of the substrate. Different factors that affect focusing, such as the aperture angle and the configuration of the IDT fingers, were systematically addressed. We show that the focusing performance can be considerably improved by appropriate choice of the IDT metal pads, which, under appropriate conditions, create an acoustic waveguide within t…
Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV
2017
In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of …