Continuous-wave operation of vertically emitting ring interband cascade lasers at room temperature

Abstract

We present vertical light emission in continuous-wave mode from an interband cascade laser (ICL) at a record temperature of up to 38 °C. These results pave the way toward a more efficient and compact integration of this technology in mobile spectroscopic applications. Our approach employs ring cavity ICLs that are mounted epi-side down for efficient heat extraction from the devices. The vertical single-mode emission relies on a metallized second-order distributed-feedback grating designed for an emission wavelength of 3.8 μm. A single lateral mode operation is favored by a narrow waveguide width of 4 μm. Optical output powers of more than 6 mW were measured at 20 °C for rings with a diameter of ∼800 μm. At this temperature, the threshold current-density amounted to $0.60\hspace{0.17em}\text{kA}/{\text{cm}}^2$ and the device showed continuous current and temperature tuning rates of 0.06 nm/mA and 0.37 nm/K, respectively.