Short-external-cavity module for enhanced single-mode tuning of InGaAsP and AlGaAs semiconductor diode lasers

The construction and single-mode tuning characteristics of a short-external-cavity (SXC) module for InGaAsP and AlGaAs semiconductor diode lasers are presented. The SXC system is a cost effective, simple, and rugged means to achieve single-mode tuning and complete spectral coverage over large spectral regions with normally multimode lasers. With AlGaAs lasers, complete spectral coverage in overlapping ∼5-cm−1 intervals over ∼400 cm−1 is obtained, while with InGaAsP diode lasers, complete spectral coverage in overlapping ∼5-cm−1 intervals of 100–200 cm−1 is obtained.