We present investigations on coherent coupling of surface emitting quantum cascade lasers (QCLs). For this purpose, the evanescent field coupling method is exploited under incorporation of a ring cavity surface emitting QCL pair with an emission wavelength of ≈8 μm. A series of these pairs with intercavity separations of 1 and 3 μm was fabricated. The coupling gap of 1 μm yields robust phase-locked light source pairs with coherent emission at all injection currents and a corresponding threshold current density of 2.65 kA/cm2 at room-temperature.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)