The emission spectra of several commercial InGaAlP laser diodes operating in the visible range are investigated. Large free-running linewidths on the hundred MHz level and relaxation oscillations at frequencies up to 2 GHz were observed in the field spectra. Linewidth reduction to less than one MHz has been achieved with resonant optical feedback on the cost of strong relaxation oscillations. With a short extended cavity configuration we could get both narrow linewidths on the MHz level and strong damping of the relaxation oscillations. Keeping the cavity length short, stable operation was achieved without any additional anti-reflection coating of the laser diode. A combination of the two methods gave additional strong reduction in the laser linewidth to roughly 50 kHz. To demonstrate the feasibility of the short extended cavity lasers in the visible range, the calcium intercombination line at 657 nm was reported with high resolution using an atomic beam apparatus.

Date Published: 30 April 1993
PDF: 12 pages
Proc. SPIE 1837, Frequency-Stabilized Lasers and Their Applications, (30 April 1993); doi: 10.1117/12.143697

Published in SPIE Proceedings Vol. 1837:
Frequency-Stabilized Lasers and Their Applications
Y. C. Chung, Editor(s)