Monolithic High-Contrast Grating Based Polariton Laser

Abstract

High-reflectance gratings promise new generations of vertical-cavity lasers that allow flexible control of the lasing mode properties and better integration. To date, conventional and polariton vertical-cavity lasers have been created with high-contrast gratings surrounded by air. Suspended in air, these gratings are delicate to fabricate and use, and are difficult for precise property control, electrical injection or thermal management. Here, we demonstrate a high quality vertical-cavity laser with a nonsuspended monolithic grating. High reflectance is achieved to allow the strong coupling regime, verified by angle-resolved photoluminescence measurements. We demonstrate polarized polariton lasing, manifested by a super-linear increase in the polariton emission and linewidth narrowing. We also demonstrate multi-wavelength operation of the polariton laser, with the wavelength controlled by design.

Direct Generation of Radially Polarized Vector Vortex Beam with an Exciton-Polariton Laser

“…A schematic of the SWG-based microcavity is shown in Fig. 1a It has been shown that an SWG made of straight, periodic bars can function as a polarization-selective mirror with high enough reflectance to support polariton lasing [28,29]. This is because the guided wave resonances in the grating are polarized parallel or perpendicular to the grating; they can be designed to interfere at the surface of the grating to allow nearly perfect reflectance for one of the polarizations, while the orthogonally polarized mode has low reflectance [30][31][32][33].…”

“…1b) with diameters up to 8.65 µm. The grating parameters are optimized to have high reflectivity only for light polarized perpendicular to the grating bars (transverse-magnetic, TM) incident from the cavity [28], including a grating period of about 336 nm and a duty cycle, defined as the ratio of the width of the high-index material to the period, of about 0.7.…”

“…To further facilitate polariton condensation, we utilize the design flexibility of SWG to engineer a trapping potential landscape [34]. The period and duty cycle of the grating can be tuned to change the reflection phase of the grating, and consequently change the resonance energy of the cavity [28]. Changing the duty cycle of the grating along the radial direction, from 0.7 at the center to 0.65 at the edge, we create a circular trapping potential of about 2 meV for the polaritons.…”

“…Instead, the lasing mode is determined by the structure of the microcavity. This is achieved by using a concentric circular dielectric sub-wavelength grating (SWG) in lieu of a flat mirror [28] to enable control of the polarization vector of the cavity mode. Polariton lasing in radially polarized spin vortex state is experimentally observed.…”

Influence of Various Bottom DBR Designs on the Thermal Properties of Blue Semiconductor-Metal Subwavelength-Grating VCSELs

“…Our numerical findings were confirmed by experimental characterization of the power reflectance spectrum [18] of a stand-alone MHCG fabricated from GaAs and designed for a wavelength of 980 nm. In [19], Kim et al reported first MHCG-cavity polariton laser and later we showed the first electrically-injected MHCG VCSEL with peak emission wavelengths of 980 nm and continuous wave lasing up to 75 ∘C [20].…”