Optical parametric oscillators (OPOs) have been widely applied in areas ranging from spectroscopy photonics to quantum information. While conventional OPOs typically suffer from weak nonlinearity which leads to high power consumption, exciton polaritons offer a smart alternative.
Hybrid quasiparticles composed of light and matter, exciton polaritons possess a nonlinearity that is orders of magnitude stronger than traditional nonlinear photonic systems, promising significantly lower power consumption. Such nonlinearity plays essential roles—not only in conceptual polaritonic devices such as neuromorphic computing systems, but also in the emerging nonlinear quantum regime, with polariton blockade and quantum simulations.
Polariton parametric oscillators with low thresholds have been realized in a variety of geometries, yet the small exciton binding energies of those oscillators have meant that they are mostly limited to quantum-well microcavities of gallium arsenide or cadmium telluride, which demand cryogenic cooling. Room temperature devices are needed.
Halide perovskites have rapidly emerged as excellent semiconductors for photonic technologies ranging from LEDs and lasers to photodetectors. More recently, toward engineering their applications in next-generation photonic devices, the nonlinear properties of perovskites have attracted tremendous interest. With advantages such as large exciton binding energy and strong nonlinear polariton–polariton interaction, halide perovskites present a promising platform for nonlinear, low-threshold polaritonic devices that work at room temperature.
As reported in Advanced Photonics, researchers from Nanyang Technological University, Singapore, and Tsinghua University, China, recently developed on-chip, low-threshold perovskite polariton parametric oscillator that operates at room temperature. Thanks to an S-shaped lower polariton energy dispersion, intrabranch parametric oscillation occurs when two polaritons are resonantly excited with a critical angle, scattering elastically to the ground state (signal) and a higher k state (idler). With the intrinsically open (non-Hermitian) quality of polaritons, a spontaneous parametric down conversion process can occur at a wide range of angles, a feature that affords great flexibility for design.
According to senior author Qihua Xiong, professor of physics at Tsinghua University, "This work offers a practical way to achieve integrated nonlinear polaritonic devices with low thresholds." Room temperature operation opens possibilities for development of low-cost, scalable polaritonic devices.
Read the open access article by Jinqi Wu et al., "Perovskite polariton parametric oscillator," Adv. Photonics 3(5), 055003 (2021), doi 10.1117/1.AP.3.5.055003.