Surface-emitting microlaser combining two-dimensional photonic crystal membrane and vertical Bragg mirror

Abstract

We report on the design and fabrication of heterogeneous and compact surface-emitting microlasers, optically pumped and operating at 1.5μm at room-temperature. A very low threshold, below 15μW, is achieved. The devices consists of a top two-dimensional InP photonic crystal slab, including four InAsP quantum wells, a SiO2 bonding layer, and a bottom high index contrast Si∕SiO2 Bragg mirror deposited on a Si wafer. The graphitelike photonic crystal lattice is tailored for vertical emission. We theoretically and experimentally demonstrate that the Bragg reflector can strongly enhance the quality factor of the photonic crystal resonant mode, leading to a drastic decrease of the lasing threshold.

3D harnessing of light with 2.5D photonic crystals

“…First, the strength of the resonance can be set by the thickness of the spacer layer so-called "cavity" in between the PC membrane and the Bragg reflector ( Fig. 5b) [32]. For a half-wavelength cavity, coupling of the resonance with radiated modes is promoted and the quality factor is reduced by a factor of 2.…”

“…This means that the field distribution of the hybrid mode is principally confined within the PC membrane (or that it is reduced to its waveguided component) and its resonant wavelength is locked to that of the plain PC membrane; therefore, tuning is made possible by the sole action on the latter (for example by the modulation of the optical index of the membrane). The only useful action of the Bragg reflector is to result in an increased factor of the resonance (multiplied by the amount 1 1 RBragg ): this particular configuration has been successfully exploited for the production of record low threshold microlasers and optical bistable devices [32,33].…”

All-optical bistable band-edge Bloch modes in a two-dimensional photonic crystal

“…As discussed elsewhere, 8,9 such modes can be used to achieve low threshold lasing on highly compact structures. Indeed, the minimum threshold depends linearly on the curvature of the photonic band around the extremum.…”

Compact hollow-core photonic band gap resonator with optimised metallic cavity at microwave frequencies

“…3). This may be overcome by including horizontal Bragg reflectors [7]. The loaded Q-factor that has been measured with a single ring enclosed in hexagonal side walls is as high as a four-ring without metallic side walls (black squares, inset (a) in Fig.…”