Abstract: The invention discloses an actively Q-switched laser with an intracavity nonlinear coupler in which a stable optical frequency converted output is generated. A Gain Fluctuation Insensitivity Condition is defined and described for several examples. The nonlinear coupler with a coupling level which satisfies this Condition permits stable laser operation with minimal interaction between pulses, even when the pulses are clipped by the Q-switch. Thus, the output pulse duration and repetition frequency of the disclosed laser can be varied over a large range substantially independent of laser gain level and dynamics. Second and third harmonic optical frequency conversion is demonstrated, although the disclosed laser is applicable to other optical frequency conversion regimes as well.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: A wavelength conversion device in which the fundamental wave is converged in a non-linear optical crystal for effecting wavelength conversion, and in which no significant peak is generated in the non-linear optical crystal even if the power of the input fundamental wave is high. The spot radius at the converging point of the fundamental wave is selected to be 0.0014 to 0.0023 cm, while the crystal length of the non-linear optical crystal is selected to be 0.5 to 1.2 cm. If this range is met, the light intensity distribution in the non-linear optical crystal becomes of the top hat type, such that no peak is generated.

Abstract: A genetic recombination laser apparatus includes an optical system having a semiconductor laser medium for generating a semiconductor laser light, an Nd:YAG crystal, an LBO and .beta.-BBOs for reducing the wavelength of the laser light, an acoustic optical device and a lens for converging the laser light with a reduced wavelength;. A stage for positioning the focus of the laser light converged by the lens at any arbitrary location on a specimen is provided. The energy of the laser light converged on the specimen is set at a value greater than the bonding energy of the substance composing the wall of the somatic cell. Preferably, the semiconductor laser light is converted into the fifth harmonic of an Nd:YAG laser light having a wavelength of 213 nm and a second harmonic with a wavelength of 532 nm generated in the conversion process is used as for positioning the focus of the laser light converged by the lens on the specimen.