Yoshito Niwa

Diode-pumped 250-W zigzag slab Nd:YAG oscillator–amplifier system

A laser-diode-pumped zigzag slab Nd:YAG master oscillator power amplifier (MOPA) system featuring high pulse energy and high average power was developed for pumping of an ultrashort-pulse laser system. The MOPA system consists of an oscillator, a preamplifier, two postamplifiers, and image-relay telescopes. The postamplifiers have an angle-multiplexed ring-type double-pass configuration. A pulse energy of 1.26 J and an average power of 251 W were obtained at a repetition rate of 200 Hz. The frequency-doubled power when a LiB(3)O(5) crystal was used was 105 W at a repetition rate of 170 Hz. The intensity profiles of the fundamental and the second harmonic are nearly top-hat shaped and are suitable for pumping.

High-repetition rate 1-J green laser system

A laser-diode-pumped high-repetition-rate zigzag slab Nd:YAG oscillator-amplifier system is developed as the pumping source of a high-average-power and terawatt Ti:sapphire chirped pulse amplification laser system. This system can produce a greater than 2-J high-energy fundamental laser pulse at a repetition rate of 100 Hz. The frequency-doubled energy with a diffusion-bonded KTP crystal is 1 J at a repetition rate of 100 Hz.

High-repetition-rate 2-J Nd:YAG oscillator-amplifier system

Advances in high-repetition-rate high-average-power ultrashort-pulse laser systems1–3 are expected to be utilized in many applications, such as higher-harmonic generation4 and material processing,5 that require high average flux. However, the average power of such systems is still limited to several watts because the average power of pump sources has been limited to tens of watts.

Ring Self-Pumped Phase Conjugator for High Energy Pulses at 1064 nm with Rhodium-Doped BaTiO3

An external loop phase conjugate mirror with a 45°-cut rhodium-doped BaTiO3 is constructed and characterized. The external loop is composed of an image-relay telescope, a 90°-image rotator and a phase modulator. The stable phase conjugation is achieved with nanosecond 20 mJ pulses at 1064 nm. Reflectivity of the mirror as high as 53% is obtained with a response time of 13 s at a repetition rate of 100 Hz. Wavefront compensation is applied to a laser beam whose quality is as poor as M2 > 100.

LD-pumped 0.62-J 105-W Nd:YAG green laser

Laser diode pumped zigzag slab Nd:YAG MOPA (Master Oscillator Power Amplifier) system featuring high pulse energy and high average power has been developed for the pumping of ultra- short pulse laser system. The MOPA system consists of an oscillator, a preamplifier, two postamplifiers and image relay telescopes. The post amplifiers has an angle multiplexed ring type double-pass configuration. A pulse energy of 1.26 J and an average power of 251 W are obtained at the repetition rate of 200 Hz. The frequency doubled power using a LBO (LiB3O5) crystal is 105 W at the repetition rate of 170 Hz. The intensity profiles of the fundamental and the second harmonic are near top hat and is suitable for the pumping. In a preliminary experiment, effectiveness of the MOPA as a pump source of all solid state chirped pulse amplifier (CPA) system is demonstrated.

Photorefractive phase conjugator for Nd:YAG laser system

Abstract An external loop phase conjugate mirror with a 45°-cut rhodium-doped BaTiO3 is constructed and characterized. The external loop is composed of an image-relay telescope, a 90°-image rotator and a phase modulator. An Nd:YAG laser with the phase conjugate mirror produces a pulse energy of 330 mJ at 100 Hz with a beam quality of 1.2×DL.

Nd:YAG oscillator-amplifier with a photorefractive phase conjugator

A ring type self-pumped phase-conjugate mirror with rhodium- doped barium titanate is used to correct aberrations of an LD- pumped sigzag slab Nd:YAG oscillator-amplifier system. A diffraction limited output of 360 mJ is achieved at the repetition rate of 100 Hz.

Ring self-pumped phase conjugator for high energy pulses at 1064 nm with rhodium-doped BaTiO/sub 3/

Summary form only given. We investigate a self-pump phase conjugator (SPPC) for the improvement of beam quality of a Nd:YAG master-oscillator power amplifier (MOPA). To achieve high energy operation, we employ an external loop SPPC geometry of a BaTiO/sub 3/:Rh crystal, the so-called ring SPPC, unlike the internal loop geometry.

High repetition-rate 1-J green laser development

Summary form only given. For the pumping of an ultra high average power Ti:sapphire CPA system, a high average power Nd:YAG green laser has been developed. The development approach is a diode pumped zigzag slab Nd:YAG master oscillator power amplifier (MOPA) and a second harmonic generator (SHG).