Single-mode fast-tunable lasers for laser-diode spectroscopy

Physical mechanisms leading to the suppression of instability in the electron-hole plasma under conditions of population inversion and, thus, promoting single-mode lasing and drive-current-controlled tuning were studied; in particular, nonuniform injection and spatial oscillations of laser flux were considered. Transient times typical of current-and heat-aided tuning are measured. The effective time constant is estimated as ∼1 µs for heat-controlled tuning; by contrast, it is at least one order of magnitude shorter for current tuning. The tuning range does not exceed several angstroms and is as wide as 100 Å in the case of heat-and current-aided tuning, respectively. A single-mode fast-tunable heterolaser which is capable of operating within the 2.8–3.6 µm wavelength range at 12–120 K and is designed for laser-diode spectroscopy is developed. The results of using the laser for the detection of absorption spectra in OCS, NH 3 , CH 3 Cl, CH 4 , N 2 O, and H 2 O vapors are reported.