Abstract

When a sub-Poissonian light is utilised for a spectroscopic light source in order to get high sensitivity beyond the standard quantum noise limit, how to get a wide tuning range remaining sub- Poissonian nature and how to get suitable modulation of the source are severe problems. We have improved the spectral stability (jitter < 5 MHz) and the continuous tuning range (≈ 80 GHz) of a sub- Poissonian (≈ -2 dB) light from a semiconductor laser. It is oscillating at 810 nm and the power is about 10mW. The tuning range is still limited by a residual cleavage-cavity component of the laser element. As for the modulation of the light source, we have tried two schemes. One is making use of its intrinsic frequency noise [1], and the other is injecting a weak laser light.

© 1996 Optical Society of America