Switchable two-wavelength emission using vertical external-cavity surface-emitting laser

Abstract

We present an optically pumped vertical external-cavity surface-emitting laser (VECSEL) that can emit two switchable wavelengths from a single chip, with a wavelength separation of more than 40 nm. Quantum wells with two gain wavelengths are used in the active region of the gain chip. The Fabry–Perot dips in the reflectivity spectra of the VECSEL are designed to support two wavelengths. The VECSEL can simultaneously emit wavelengths of 955 and 997 nm at the pump power of 15.4–16 W; the maximum dual-wavelength output power is ~250 mW. The emitting wavelength can be switched between 950 and 1004 nm as the pumping power is changed. The output power exceeds 280 and 500 mW at 955 and 1004 nm, respectively, mainly because of the internal self-heating generated by the optical pumping process, which can quickly change the temperature of the gain chip and cause redshift of the gain peak. The temperature rise of the gain chip can change the offset between the gain peak and cavity mode, thereby changing the output wavelength.