SBS Pulse Compression Research Articles

Experimental optimization of compact double-cell stimulated Brillouin scattering pulse compressor

To optimize the output of SBS sub-nanosecond pulse compression, two kinds of compact double-cell structures are carried out and compared experimentally. The beam parameters of the compact double-cell structure are calculated theoretically, which provides the selection guidance of structural parameters such as lens focal length and SBS cell size. The dependence of lens parameters and medium parameters on SBS output parameters are experimentally studied. Results show that SBS pulse compression enters the saturation region at a low injection energy with a long focal length lens or a large gain coefficient medium. For compact double-cell setup with one lens, it is easy to obtain narrow pulses for the medium FC40 with a short phonon lifetime. While in setup with two lenses, it is easy to obtain SBS output with a high energy efficiency and narrow pulse width for HT110 medium with a large gain coefficient. The pulse width compression ratio is up to 16 times after optimization. These experimental results can provide references for the experimental design of SBS pulse compression.

SBS pulse compression using bulk fused silica by diode-pumped solid-state lasers at 1 kHz repetition rate

This study is focused on constructing a highly stable diode-pumped solid-state laser system by conducting experiments on high-repetition-rate SBS pulse compression using bulk fused silica. A multi-rod serial-connection structure is adopted for SBS expriments by comparing K8 glass and fused silica medium at a 10 Hz repetition rate. The optimized structure is obtained according to variation of the pump power density. Based on the optimized structure, fused silica-based SBS pulse compression is carried out in the range of 100–1000 Hz and the parameter performance of laser system after compression is also evaluated by comparing a HT270 liquid medium. Experimental results indicate that the energy efficiency of fused silica-based SBS is improved by approximately 40% compared with that of K8 glass. Further, the energy relative standard deviation of fused silica-based SBS is reduced by approximately 88% compared with HT270 medium, indicating that bulk fused silica is advantageous for high-repetition-rate SBS pulse compression because of its un-fluidity, high thermal conductivity and power-load ability. In addition, a 1 kHz highly-stable sub-nanosecond compressed pulse is achieved using bulk fused silica medium at a pump energy of 50 mJ. Furthermore, the SBS energy efficiency can be further improved by increasing the input energy.

Eye-safe picosecond Raman laser

The results of development of a picosecond Nd :YAG laser with SBS and SRS pulse compression are presented. The laser emits single-frequency radiation (one longitudinal cavity mode of a passively -switched master oscillator) with a pulse energy of at a pulse duration of about and a pulse repetition rate of . The output laser wavelength is . The laser beam quality is close to the diffraction limit . Thermally induced phase distortions introduced into the laser beam by the active elements of laser amplifiers are studied and a method of their compensation is proposed. Using this method, we have developed, fabricated, and successfully tested aspherical optical elements compensating for thermal aberrations of active elements, which has allowed us to decrease the beam divergence and increase the output energy.

Laser with SBS Pulse Compression for LIBS

Laser with SBS Pulse Compression for LIBS

Repetitively Pulsed Solid-State Laser System with SBS Pulse Compression

Repetitively Pulsed Solid-State Laser System with SBS Pulse Compression

Repetitively pulsed solid-state laser system with SBS pulse compression

A repetitively pulsed solid-state laser system with a new version of a pulse compression scheme based on stimulated Brillouin scattering is proposed. The scheme allows us to work in a wide energy range from 100 mJ to several Joules, with a compressed pulse as short as 150–300 ps.

SBS pulse compression to 200 ps in a compact single-cell setup

Temporal compression of nanosecond pulses from a commercial Q-switched Nd:YAG laser at second and third harmonic into the sub-nanosecond regime is demonstrated. In a geometry consisting of a single cell only, compression in several liquid media is investigated. For both 532 and 355 nm smooth and reliable operation is obtained with output pulses as short as 200 ps. A new concept is proposed to separate SBS pulses from the pump beam at low optical losses.

Recent developments in LIDAR Thomson scattering measurements on JET (invited)

The LIDAR Thomson scattering technique uses the time of flight of a short laser pulse to spatially resolve measurements of electron temperature (Te) and density (ne) in a plasma. The technique was pioneered at JET and the first profiles were obtained in 1986. The initial system used a 3 J, 0.5 Hz, 300 ps ruby laser and microchannel-plate photomultiplier detectors to make Te and ne profile measurements with ∼10 cm spatial resolution. Since then we have sought to improve both the spatial resolution and frequency of measurement during a JET pulse. It has proved possible to develop a 4 Hz version of the ruby laser and to enhance the rate of cycling of detection and digitizing to match. The main LIDAR system has now been upgraded to 4 Hz and first JET profiles obtained with the new system are presented. For a LIDAR system, the spatial resolution δL along the laser path is given by δL=(c/2)(τ2L+τ2D)1/2, where c is the velocity of light, τL the laser pulse width, and τD the detection system response time. Over a limited spatial extent it is possible to improve spatial resolution by using a streak camera detection system. We have successfully improved the spatial resolution by a factor of 2 by setting up a streak camera detection system in parallel with the main photomultiplier system. The much shorter response time of the streak camera gave ∼5 cm resolution over a 75 cm segment of the ∼2 m plasma diameter. This system was used to examine profile details in the outer part of the JET plasma. Results from this high-resolution LIDAR detection system will be presented. Building on the improved spatial resolution obtained with the streak camera technique, we have now designed and installed a new LIDAR scattering system to diagnose the divertor region of the JET plasma. The laser for the new system is again ruby but uses a different principle to obtain short pulses. We have demonstrated with colleagues from the Troitsk Institute the conversion, using SBS pulse compression, of a standard 25 ns ruby laser into a 300 ps system suitable for LIDAR applications. The main components of the JET Divertor LIDAR system are also described.