Y. Ojima
Chiba University
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Publication
Featured researches published by Y. Ojima.
Optics Express | 2006
Kouji Nawata; Y. Ojima; Masahito Okida; T. Ogawa; Takashige Omatsu
We investigated design issues for the power scaling of a pico-second Nd:YVO(4) master-oscillator power amplifier system with a photorefractive phase-conjugate mirror by using standard beam propagation analysis. We also demonstrated a 25 W diffraction-limited pico-second output. A corresponding extraction efficiency of 31 % was achieved.
Optics Express | 2005
Y. Ojima; Kouji Nawata; Takashige Omatsu
We have produced a high beam quality pico-second laser based on a continuous-wave diode pumped Nd:YVO4 slab amplifier with a photorefractive phase conjugate mirror. 12.8W diffraction-limited output with a pulse width of 8.7ps was obtained.
Optics Express | 2005
Takashige Omatsu; Y. Ojima; A. Minassian; M. J. Damzen
High power operation of highly-doped ceramic Nd:YAG laser is demonstrated using a laser diode transversely-pumped bounce geometry. Using a 2% doped ceramic Nd:YAG amplifier, an output power of 45W was achieved with 158W diode pumping. The cavity configuration was optimized for TEM00 operation and a high spatial quality output (M2 >1.5) was obtained at an output power of 27W. A ceramic Nd:YAG laser with 4% doping was operated at over 1 watt of output power. These are the highest power levels achieved in ceramic Nd:YAG lasers at >1% doping level.
Japanese Journal of Applied Physics | 2004
Toru Imaizumi; Masato Goto; Y. Ojima; Takashige Omatsu
We present a full characterization of a pico-second pulse generation from a Nd:YVO4 double-pass amplifier with a phase-conjugate mirror based on a photorefractive BaTiO3 crystal with an external loop geometry. With this system, 7.4 W diffraction-limited pico-second output was generated. A corresponding optical extraction efficiency of >20% was achieved.
Journal of Optics | 2003
Takashige Omatsu; T Imaizumi; M Amano; Y. Ojima; K Watanabe; M. Goto
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.
Optics Express | 2005
Y. Ojima; Takashige Omatsu
We demonstrate 80 times phase conjugation by four-wave mixing of pico-second pulses in a diode-pumped Nd:YVO4 amplifier. Slight pulse broadening as a result of four wave mixing processes was observed.
conference on lasers and electro optics | 2005
Y. Ojima; Masato Goto; Takashige Omatsu
We demonstrate a high average power pico-second laser system based on a continuous-wave diode pumped Nd:YVO 4 slab amplifier with a bounce geometry. With this system, a high quality pico-second output of > 10W was obtained.
conference on lasers and electro optics | 2005
Y. Ojima; M. Goto; Takashige Omatsu
In this paper, we present a characterization of self-pumped ring phase conjugate mirror (PCM) based on a Rh:BaTiO/sub 3/ crystal with 1 /spl mu/m chirped pulses. The experimental phase conjugate reflectivity of as much as 30% was obtained. And an interesting pulse compression phenomenon was also observed.
conference on lasers and electro optics | 2005
Y. Ojima; Takashige Omatsu
In this paper, we present a 80-times phase conjugation for pico-second pulses by four-wave-mixing (FWM) in a diode-pumped Nd:YVO/sub 4/ slab amplifier. The reflectivity is the highest value, to the best of our knowledge, obtained by phase conjugation in pico-second regime.
conference on lasers and electro optics | 2005
M. Goto; Y. Ojima; Takashige Omatsu
In this paper, we demonstrate a 10 W class pico-second laser system based on a continuous-wave diode-pumped Nd:YVO/sub 4/ slab double-pass amplifier with a bounce geometry. This is the highest value, to the best of our knowledge, obtained by pico-second double-pass lasers in the bounce amplifier configuration. The M/sub x//sup 2/ and M/sub y//sup 2/ of the output were 3.0 and 1.7, respectively.
