Abstract

The spatial coherence of a light source can be easily controlled by varying the source size. The temporal coherence of a light source, on the other hand, has proved to be much more difficult to control. The dependence of the laser diode emission wavelength on temperature offers an opportunity for direct control of their temporal coherence. By modulating the Injection current, temperature fluctuations in the semiconductor junction produce a controlled wavelength drift In the emitted radiation. The amount of wavelength drift can be varied by regulating the depth and period of the modulation which over the integration period translates into variable spectral bandwidths. Thus, a wide range of temporal coherence lengths can be synthesized by appropriately modulating the laser diode current. Possible applications of the technique are described.

© 1986 Optical Society of America