Optical diode based on exciton-polaritons

Abstract

We propose theoretically an optical diode based on exciton-polaritons in semiconductor microcavities. A flow of polaritons in the bistable regime is used to send signals through an asymmetric fixed potential that favours the tunneling of particles in one direction. Through dynamic modelling of the coherent polariton field, we demonstrate the characteristics of an ideal diode, namely that the forward signal is fully transmitted while the transmission in the reverse direction tends to zero, without any additional external control. Moreover, the system proves to be robust to the presence of disorder, intrinsic to microcavities, and can function at gigahertz repetition rates. A common problem for the linking of polaritonic devices is the compensation of loss due to photon emission. The amplification of polariton states by bosonic stimulation 18-21 was one of the first nonlinear effects studied in these systems and propagating polariton wavepackets were recently amplified through a non-resonant excitation of reservoir states22 . An alternative approach to amplification has been based on the bistable behaviour of polaritons [23][24][25] , which itself has been used to create polariton switches 26,27 and ultrafast memories 28 . In the bistable regime, a switched state survives indefinitely 28 where the loss is compensated by a continuous wave laser that, together with interactions, sets the bistability in the system. By exploiting the propagation of a domain wall, it has been predicted theoretically that one can transport loss-less signals in the microcavity plane 29,30 . Structured potentials control the signal propagation along wires or "polariton neurons" and signals can cover distances that go far beyond the limits expected of the polariton lifetime.To be competitive, a signal processing device needs to achieve a low error rate, which may require the suppresa) Electronic mail: teortega@ntu.edu.sg sion of feedback. A useful element to reduce feedback would be a polaritonic analogue of the diode -a device that ideally allows full signal transmission in one direction, with signal suppression in the other. Very recently, a double barrier resonant diode based on polaritons was constructed 31 , where a high contrast gating of the transmission was achieved through the application of a gating laser. This design was based on ballistically propagating polariton wavepackets 32 . In this paper we present a design for an optical diode compatible with propagating domain walls (polariton neurons). An asymmetric response is achieved without using an additional gating laser, instead making use of a fixed spatially patterned potential, which favours the tunneling of particles in one direction only. We show that it is possible to achieve 100% transmission for the forward signal, while the backward signal is fully blocked by the static potential. Without the action of any external electric or optical control potential, the device can operate as a tunnel diode or as a backward diode, depending on the direction of the incoming flow of p...

Switching waves in multilevel incoherently driven polariton condensates

“…It has been shown that exciton-polariton systems give rise to bistability under resonant pumping schemes [5][6][7] with applications in photonic logic gates [8][9][10] , switches and memory elements [11][12][13] , control of polariton superfluids 14 , and optical diodes 15 . Under resonant excitation a number of works focused on the parametric instability between polaritons [16][17][18][19][20] , where polaritons in one particular energy-momentum state scatter in pairs to "signal" and "idler" states conserving energy and momentum.…”

Microcavity exciton polaritons at room temperature

“…Recently, room temperature operation of an all-optical binary switch was indeed demonstrated using self-assembled perovskite microwires [142] . Other required optical components such as memory devices [143,144] , diodes [145,146] , routers [147][148][149] , and optical amplifiers [150] are required for room temperature optical computing. A universal logic gate set and a method of cascading them are also required [151] .…”

Suppression of space broadening of exciton polariton transport by Bloch oscillation effect

“…yyzhang@bit.edu.cn [19]. These developments are the foundation of the accurate design of the microcavity devices, such as optical diodes [20] and quantum circuits [21][22][23]. Generally speaking, it is easier to design the photonic potentials than to design the excitonic ones.…”