IV The Ultrafast Optical Kerr Shutter

Abstract

One particularly useful application of picosecond laser pulses, which is the object of this chapter, has been in the development of an ultrafast shutter (or gate) based on the optical Kerr effect. This effect refers to the very short-lived birefringence induced in transparent mediums by high-power laser pulses propagating therein. The ultrafast optical Kerr shutter uses this optically induced birefringence to gate light on and off on the picosecond time scale, much in the way in which the conventional Kerr cell uses an electrically induced birefringence to gate light on and off on the nanosecond time scale. The ultrafast optical Kerr shutter found a number of applications, some of which are addressed in the chapter. The Kerr shutter is applied to the measurement of some interesting molecular relaxation times. Of more general interest has been the use of the ultrafast shutter in displaying the time profile of a variety of optical signals. Another recent application of the ultrafast gate is in the measurement of ultrashort x-ray pulses emitted by laser produced plasmas. For this the x-rays are converted into light in a plastic scintillator, and the light is measured on the picosecond time scale with the optical sampling oscilloscope technique.