ABSTRACT
InAsSb/InAsSbP double heterostructure diode lasers for the spectral range of 3-4 microm grown by liquid phase epitaxy have been investigated. The laser tuning was studied as a function of the stripe width. The temperature and current tuning of such lasers was measured. Emission spectra, far-field patterns and wavelength tuning versus current have been studied in the wide current range from threshold, Ith, up to 6Ith at liquid nitrogen temperature. Current wavelength tuning in single-mode lasing has been obtained both towards the shorter wavelengths (up to 4.56 cm-1) and towards the longer wavelengths (up to 0.9 cm-1) at the temperature T=77K. Comparison of the emission properties of the lasers, driven by different types of current pulses showed the same quantum-mechanical nature of current tuning. The theoretical model of this nonlinear optical phenomenon is proposed. The estimated times of current tuning defined mainly by the photon lifetime in the cavity are about 10(-9) to 10(-12) s. The emission line-width was determined to be 20 MHz. Optimal conditions were found for the use of the lasers and were employed for the detection of NH3, CH3Cl, OCS and atmospheric water.
Subject(s)
Lasers , Ammonia/analysis , Atmosphere/chemistry , Methyl Chloride/analysis , Spectrum Analysis , Temperature , Time Factors , Water/analysisABSTRACT
A new type of semi-conductor laser with composition InAsSb/InAsSbP is described. This laser was produced for the absorption spectroscopy of atmospherically important molecules in the 3100 cm(-1) region and tested using a closed-cycle He-cryostat in the temperature range 30-80 K. The optimal characteristics of the laser were found to be a heatsink temperature of 62 K and a drive current range of 50-350 mA. Under these conditions, the laser emits single-mode radiation in an exceptionally large wavenumber range of > 10 cm(-1). To test the laser, several experiments were carried out in which the rovibrational absorption spectra of CH3Cl, NH3, OCS and H2O were measured.