Switchable two-wavelength frequency-converting laser system and power

Abstract

A laser system and power control have a polarization state changer that produces in response to an incident beam with selected polarization state at a first wavelength .lambda..sub.1 a beam at .lambda..sub.1 with a desired polarization state. A frequency converter responds to the beam at .lambda..sub.1 with the desired polarization state to produce a frequency converted beam at a second, different wavelength .lambda..sub.2. When the polarization state changer and the frequency converter are located within a laser cavity, the laser system is operable in three different states and produces an output beam at .lambda..sub.1 or .lambda..sub.2, or no output beam, depending on the polarization state changer. In this intracavity configuration the polarization state changer is also operable as a Q-switch. When the polarization state changer and the frequency converter are located outside a laser cavity, the polarization state changer is operable in the whole range between its first and third states; the device thus produces an output beam at .lambda..sub.2, an output beam including components at .lambda..sub.1 and .lambda..sub.2, or an output beam having no component at .lambda..sub.2, again depending on the polarization state changer. In the extracavity configuration the power in the output at .lambda..sub.2 is continuously controllable between a maximum and zero.