Lightwave synthesizer with lock-in-detected frequency references

The authors describe a lightwave synthesizer system based on the lock-in detected frequency references such as atomic or molecular spectra. This system uses two semiconductor laser diodes (LDs); one is a frequency-tunable master LD, and the other is a frequency-modulated tracking LD, used for stabilizing and tuning the master LD. The lightwave-frequency tuning of the master LD is controlled by a microwave synthesizer. This yields the same frequency stability and accuracy as the lock-in-detected frequency reference at anywhere in the tuning range. By using the 1535.39-nm absorption line of acetylene (C/sub 2/H/sub 2/) gas as the reference, tuning range of over 13 GHz with an absolute frequency stability of better than 10 MHz is demonstrated from distributed-Bragg-reflector LD.>