Tunable cw Pb0.98 Cd0.02S diode lasers emitting at 3.5 μm: Applications to ultrahigh-resolution spectroscopy

Abstract

Continuously tunable cw diode lasers that produce narrow-line (1- to 10-MHz linewidth) radiation in the 3.5-μm region have been fabricated from Pb0.98Cd0.02S. Lasers operating at 10–20 K produced more than 1 mW of cw power distributed among several modes which could be tuned continuously > 1 cm−1 by adjusting the laser current. A spectral range of 30 cm−1 could be covered over the full operating range. Ultrahigh-resolution (10−5 cm−1) spectra of H2CO have been obtained to demonstrate the potential application of these lasers to the identification of organic molecules by spectroscopy of their C–H stretch absorption bands.