Gain characterization of 2-µm GaSb VECSELs

Optically pumped VECSEL chips have the advantage of flexible and simple cavity designs allowing for tunable single frequency operation, or passive modelocking by using a semiconductor saturable absorber mirror (SESAM). In the 2-µm regime GaSb-based VECSEL have shown high-power continuous wave (cw) operation [1] . However, reports on modelocking have only shown low-power performance [2] . While photoluminescence (PL) and linear reflectance measurements indicate the lasing wavelength, they do not provide sufficient information about spectral gain and gain saturation of a VECSEL chip required for optimizing modelocking operation [3] . Gain characterization of VECSELs at mid-infrared (mid-IR) wavelengths is not reported to date. Here we present two setups to fully characterize the linear and nonlinear gain properties of mid-IR VECSELs using our near-IR knowhow [4] .