Room temperature continuous wave operation of a heterojunction bipolar transistor laser

Continuous wave laser operation at $25°C$⁠, with simultaneous electrical gain, of an InGaP–GaAs heterojunction bipolar transistor laser, with AlGaAs optical confining layers and an InGaAs recombination quantum well incorporated into the $p$-type base region, is demonstrated. At laser threshold (⁠$IB=40mA$⁠, $VCB=0$⁠, $25°C$⁠), the transistor current gain $β=ΔIC∕ΔIB$ in common-emitter operation changes abruptly $(2.3→1.2,β>1)$⁠, with laser modes developing at wavelength $λ∼1006nm$⁠. Direct three-port modulation of the transistor laser at $3GHz$ is demonstrated for a device with a $2.2μm$ emitter width and a $850μm$ length between cleaved Fabry–Perot facets (which is the performance of an exploratory device and not near the limits).