Koichi Tsuji

High-energy, diode-pumped, picosecond Yb:YAG chirped-pulse regenerative amplifier for pumping optical parametric chirped-pulse amplification.

A diode-pumped, cryogenic-cooled Yb:YAG regenerative amplifier utilizing gain-narrowing has been developed. A 1.2-ns chirped-seed pulse was simultaneously amplified and compressed in the regenerative amplifier, which generated a 35-ps pulse with ~8-mJ of energy without a pulse compressor. Second-harmonics of the amplified pulse was used to pump picosecond two-color optical parametric amplification.

Ultra-broadband optical parametric chirped-pulse amplification using an Yb:LiYF 4 chirped-pulse amplification pump laser

We demonstrate ultra-broadband optical parametric chirpedpulse amplification of 300-nm bandwidth pumped by a broadband pulse delivered from a diode-pumped, cryogenically-cooled Yb:YLF chirped- pulse amplification laser.

Multi-millijoule, diode-pumped, cryogenically-cooled Yb:KY(WO 4 ) 2 chirped-pulse regenerative amplifier

A diode-pumped, cryogenically-cooled Yb:KYW regenerative amplifier utilizing chirped-pulse amplification and regenerative pulse shaping has been developed. An amplified pulse with an energy of 5.5 mJ and a broad bandwidth of 3.4 nm is achieved.

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP.

Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Bandwidth Enhancement of Optical Parametric Chirped Pulse Amplification by Temporally Delayed Two Pump Beams

We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 350 nm bandwidth in the near-infrared region. We have observed a substantial enhancement (nearly 2-fold) of the parametric amplification bandwidth by using time-delayed two broadband pump pulses at degeneracy.

High-energy diode-pumped picosecond regenerative amplification at 999 nm in wavelength with a cryogenically cooled Yb:LuLiF 4 crystal

A diode-pumped, cryogenically cooled Yb:LuLiF(4) regenerative amplifier has been developed for the first time to our knowledge. A chirped-seed pulse was amplified and compressed in the regenerative amplifier, simultaneously, which generated approximately 6 mJ, 13 ps pulses at 999 nm in wavelength without a pulse compressor. Simultaneous lasing at 999 and 1024 nm, respectively, was demonstrated, which could be used for different frequency generation in the terahertz region.

Multi-millijoule, diode-pumped, chirped-pulse Yb:KY(WO 4 ) 2 regenerative amplifier

A diode-pumped, cryogenically-cooled Yb: KYW regenerative amplifier utilizing regenerative pulse shaping has been developed. An amplified pulse with an energy of 5.5 mJ and a broad bandwidth of 3.4 nm is achieved.

Compression of idler pulses with an identical positive dispersive media to signal pulse stretcher in ultrafast optical-parametric chirped-pulse amplification

We have proposed and demonstrated a very simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor.

Optimization for optical parametric chirped-pulse amplification bandwidth using partially deuterated KDP

Optical parametric chirped pulse amplification (OPCPA) is now recognized as a key technique to generate high peak power ultra short laser pulses [1]. In order to produce high-energy and ultrashort pulses, hybrid OPCPA design is employed, where high gain and broadband OPCPA such as BBO or LiB3O5 (LBO) crystals are used for pre-amplification and large size but lower gain OPCPA such as a Potassium dihydrogen phosphate (KDP) or deuterated KDP crystals are used as a final amplifier. However, amplification bandwidth of KDP or DKDP is narrower and the optimum phase matching wavelength is different to those of BBO.

Bandwidth enhancement of optical parametric chirped-pulse amplification by temporally delayed twin pump beams

We have demonstrated ultra-broadband optical parametric chirped-pulse amplification of more than 550-nm bandwidth by using time-delayed two broadband pump pulses at degeneracy.