Taizo Eno

High-average and high-peak output-power terahertz-wave generation by optical parametric down-conversion in MgO:LiNbO3

A widely tunable terahertz (THz)-wave generation that has a high repetition rate and a narrow line width is demonstrated in this paper by injection-seeded THz-wave parametric generation (is-TPG) in a MgO:LiNbO3 crystal. By pumping the crystal using a passively Q-switched neodymium-doped yttrium vanadate microchip laser with a time duration of 140 ps and an average power of up to 5 W, a THz-wave output with an average output power of 30 μW, a peak power of 4 W, a pulse duration of 73 ps, and a pulse-repetition frequency of 100 kHz is obtained. To prevent laser damage and photorefractive damage to the crystal, the constraints on the pumping condition of the MgO:LiNbO3 crystal are experimentally studied by changing the pumping parameters. As a result, we achieved the stable generation of the THz-wave signal in the 100 kHz regime. Moreover, we performed THz-wave imaging by using the developed is-TPG source. The obtained THz image indicated that the developed system has a good stability over long periods of time.A widely tunable terahertz (THz)-wave generation that has a high repetition rate and a narrow line width is demonstrated in this paper by injection-seeded THz-wave parametric generation (is-TPG) in a MgO:LiNbO3 crystal. By pumping the crystal using a passively Q-switched neodymium-doped yttrium vanadate microchip laser with a time duration of 140 ps and an average power of up to 5 W, a THz-wave output with an average output power of 30 μW, a peak power of 4 W, a pulse duration of 73 ps, and a pulse-repetition frequency of 100 kHz is obtained. To prevent laser damage and photorefractive damage to the crystal, the constraints on the pumping condition of the MgO:LiNbO3 crystal are experimentally studied by changing the pumping parameters. As a result, we achieved the stable generation of the THz-wave signal in the 100 kHz regime. Moreover, we performed THz-wave imaging by using the developed is-TPG source. The obtained THz image indicated that the developed system has a good stability over long periods of time.

Evaluation of composite laser crystals by output distribution on the crystal facets

We have established the evaluation technique for composite crystals by measuring the output-power distribution that depends on pumping light-source position over the crystal facet. This evaluation has contributed to improvement for yield of laser modules.

New concept of a CW coaxial fi've-wavelength DPSSL

We have demonstrated the compact and efficient watt-class CW coaxial five-wavelength DPSSL (532 nm, 593 nm, 671 nm, 1064 nm and 1342 nm) by use of Nd:YVO4 dual cavities and KTP crystals. Five wavelengths were switched by shifting of KTP crystals and output couplers.

New design of a CW coaxial five-color DPSSL

In this paper, we have demonstrated the compact and efficient watt-class cw coaxial five-color DPSSL (1342 nm, 1064 nm, 671 nm, 593 nm, 532 nm). Expanding this idea, we can select the optimum wavelength for tissue treatments at CW or QCW in a wide spectra range from visible to infra-red, without changing cavities or delivery fibers. We hThis laser shows we can select the optimum wavelength for tissue treatments at CW or QCW in a wide spectra range from visible to infra-red.

Development of the diode pumped 1 W solid state orange laser by dual pumping dual cavity

We have developed diode pumped solid state orange (593 nm) laser by use of intracavity sum frequency mixing for Nd:YVO/sub 4/ dual pumping dual cavity (1342 nm and 1064 nm). The maximum orange power was 1.29 W at 30 W pumping.

Diode-pumped solid state green laser for ophthalmologic application

We have developed diode pumped solid state green laser suitable for ophthalmologic applications. Beam parameters were designed by considering the coagulation system. We have lowered the beam quality to multi transverse and longitudinal mode on purpose to improve the speckle noise of the slit lamp output beam. The beam profile shows homogeneous intensity and it is very useful for ophthalmologic application. End pumping and short cavity configuration made it possible.