Kilohertz linewidth from frequency-stabilized mid-infrared quantum cascade lasers
15 December 1999
Frequency stabilization of mid-IR quantum cascade (QC) lasers to the kilohertz level has been accomplished by use of electronic servo techniques. With this active feedback, an 8.5-mu m QC distributed-feedback laser is locked to the side of a rovibrational resonance of nitrous oxide (N2O) at 1176.61 cm(-1). A stabilized frequency-noise spectral density of 42 Hz/root Hz has been measured at 100 kHz; the calculated laser linewidth is 12 kHz. (C) 1999 Optical Society of America OCIS codes: 000.2170, 120.5050, 120.4820, 140.5960, 000.2170.