Abstract
A cavity length control scheme was developed in order to investigate correlation between the chaotic Raman lasing of two unidirectionally coupled Raman lasers for two Ne Raman lines, 603.0 (2p2 to 1s4) nm and 659.9 nm (2p2 to 1s1). The Raman lasers were standard internal mirror He-Ne lasers and were both pumped externally by 588.2 nm radiation from a single dye laser.
The cavity lengths of each He-Ne Raman laser were monitored via the beat frequencies between the modes in the standard 632.8 nm output and the 632.8 nm modes of a stabilised reference He-Ne laser. A software based PID feedback servomechanism actively controlled the cavity length by varying the current supplied to heating pads wrapped around each cavity, altering the thermal expansion/contraction.