Single-frequency tunable Sb-based VCSELs emitting at 2.3 μm

We present a comparison between two kinds of single-frequency Sb-based semiconductor VCSELs operating at 2.3 μm in continuous-wave regime at room temperature. These lasers are studied in view of application to spectroscopy or trace gas detection. Both are based on a molecular beam epitaxy grown half-VCSEL. In the first configuration, a dielectric mirror is deposited on top to form a microcavity, while in the second a concave mirror is used to form an external cavity. The external cavity VCSEL exhibits 5-mW output power, a narrow linewidth (<<20 kHz), and 50-GHz continuous frequency tunability.