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Signal beam
About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.
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TL;DR: In this article, the results of effective optical parametric amplification in KTP crystal pumped by three beams delivered by fiber amplifiers are presented. But the results are limited to the case of optical parametrization.
Abstract: The results of effective optical parametric amplification in KTP crystal pumped by three beams delivered by fibre amplifiers are presented. The second harmonic of three 1.2 ns and 200 µJ pulses each extracted from fibre amplifier have been used to pump optical parametric amplifier (OPA) simultaneously. The conversion efficiency of pump radiation into a signal beam was close to 25%.
6 citations
23 Dec 2003
TL;DR: In this article, the authors proposed a multi-source approach employing all-solid-state modules that individually generate 300-320 nm light with pulse energies in the range of 50-200 mJ, with transform-limited bandwidths and good beam quality.
Abstract: A satellite-based UV-DIAL measurement system would allow continuous global monitoring of ozone concentration in the upper atmosphere. However such systems remain difficult to implement because aerosol-scattering return signals for satellite-based lidars are very weak. A suitable system must produce high-energy UV pulses at multiple
wavelengths with very high efficiency. For example, a nanosecond system operating at 10 Hz must generate approximately 1 J per pulse at 308-320 nm. An efficient space-qualified wavelength-agile system based on a single UV source that can meet this requirement is probably not available using current laser technology. As an alternative, we're pursuing a multi-source approach employing all-solid-state modules that individually generate 300-320 nm light with pulse energies in the range of 50-200 mJ, with transform-limited bandwidths and good beam quality. Pulses from the individual sources can be incoherently summed to obtain the required single-pulse energy. These sources use sum-frequency mixing of the 532 nm second harmonic of an Nd:YAG pump laser with 731-803 nm light derived from a recently-developed, state-of-the-art, nanosecond optical parametric oscillator. Two source configurations are under development, one using extra-cavity sum-frequency mixing, and the other intra-cavity sum-frequency mixing. In either configuration, we hope to obtain sum-frequency mixing efficiency approaching 60% by carefully matching the spatial and temporal properties of the laser and OPO pulses. This ideal balance of green and near-IR photons requires an injection-seeded Nd:YAG pump-laser with very high beam quality, and an OPO exhibiting unusually high conversion efficiency and exceptional signal beam quality. The OPO employs a singly-resonant high-Fresnel-number image-rotating self-injection-seeded nonplanar-ring cavity that achieves pump depletion > 65% and produces signal beams with M 2 ≈ 3 at pulse energies exceeding 50 mJ. Pump beam requirements can be met in the laboratory using a commercial Nd:YAG laser system, but only after extensive modifications.
6 citations
TL;DR: Gain enhancement via signal beam chopping for two-wave coupling with a Bi(12)SiO(20) crystal is demonstrated and the gain is nearly as high as that obtained with the moving interference-fringe method proposed by Huignard and Marrakchi.
Abstract: Gain enhancement via signal beam chopping for two-wave coupling with a Bi12SiO20 crystal is demonstrated. In this method the gain of a two-wave coupling scheme is increased using a transient effect. This effect is created during the grating formation due to the phase difference between the interference fringe of the light intensity incident on the crystal and the photoinduced refractive index fringe in the crystal. The maximum gain of 11.7 was achieved with an applied electric field of 6.0 kV/cm, a fringe spacing of 29.5 μm, a beam intensity ratio of 1240, and a chopping frequency of 6.0 Hz. This gain is nearly as high as that obtained with the moving interference-fringe method proposed by Huignard and Marrakchi. The gain enhancement using the transient effect caused by the polarization rotation of the signal beam (using a rotating halfwave plate) is also described. Preliminary experimental results are shown.
6 citations
Patent•
21 Jun 1985
TL;DR: In this article, a laser velocimeter with homodyne detection is constructed from a laser 1 whose linearly polarised radiation is applied in 10 to an optical system 2 of the Mach-Zender interferometer type.
Abstract: The laser velocimeter with homodyne detection is constructed from a laser 1 whose linearly polarised radiation is applied in 10 to an optical system 2 of the Mach-Zender interferometer type. The measurement beam strikes the object, whose velocity is to be measured, either directly or through a telescope 8. The signal beam S and the local oscillator beam OL are produced with a slight angular offset between them before striking a double detector 5. The angular offset is chosen so that the wavefronts of the two beams are offset by a half wavelength over the whole surface of the double detector 5. A comparison of the phases of the signals received by the two detectors gives the sign of the velocity.
6 citations
TL;DR: In this paper, a double-pass Nd:YVO4 slab amplifier with a photorefractive ring phase conjugate mirror was used to achieve a TEM00 profile with beam propagation parameters Mx2<1.4 and My2< 1.1.
Abstract: We demonstrate>4 W and 7.2 ps output of a double-pass Nd:YVO4 slab amplifier with a photorefractive ring phase conjugate mirror. A double-pass gain of 190 and optical extraction efficiency of >20% were obtained. The amplified signal beam exhibits a TEM00 profile with beam propagation parameters Mx2<1.4 and My2<1.1.
6 citations