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.