Room temperature surface emission on large-area photonic crystal quantum cascade lasers

Abstract

We design and fabricate large-area (1.1 mm $\times$ 1.1 mm) photonic crystal quantum cascade lasers, enabling single-mode (wavelength $\sim$ 8.5 $\mu$m) surface emission at room temperature, with a maximum peak power up to 176 mW. The beam divergence is $<1^{\circ }$ and without side-lobes. Moreover, by introducing asymmetry into the photonic crystal pillar shape, a single-lobed far-field is realized. The photonic band structure is measured with high spectral (0.72 cm${}^{-1}$) and angular (0.1 ${}^{\circ }$) resolution by using the photonic crystal quantum cascade laser itself as a detector.