Directional optical switching and transistor functionality using optical parametric oscillation in a spinor polariton fluid

Abstract

Over the past decade, spontaneously emerging patterns in the density of polaritons in semiconductor microcavities were found to be a promising candidate for all-optical switching. But recent approaches were mostly restricted to scalar fields, did not benefit from the polariton's unique spin-dependent properties, and utilized switching based on hexagon far-field patterns with 60° beam switching (i.e. in the far field the beam propagation direction is switched by 60°). Since hexagon far-field patterns are challenging, we present here an approach for a linearly polarized spinor field, that allows for a transistor-like (e.g., crucial for cascadability) orthogonal beam switching, i.e. in the far field the beam is switched by 90°. We show that switching specifications such as amplification and speed can be adjusted using only optical means.

Externally controlled Lotka-Volterra dynamics in a linearly polarized polariton fluid

“…A detailed numerical investigation of the present system for the following excitation conditions was already discussed in Ref. [9]. The system is excited (driven) by an x-linearly polarized continuous wave pump at normal incidence with Gaussian shape in the QW plane and an intensity slightly above the off-axis instability threshold.…”

“…If the control beam is too weak so that complete switching may not be possible, the system will remain in a stationary four-spot pattern state F. Based on this scheme, in Ref. [9] transistor- like reversible switching was demonstrated including a systematic study of switching times, minimum control power needed, and achievable gain. This was done by numerical simulations of the nonlinear set of equations of motion governing the coherent coupled light field and exciton dynamics in the microcavity system in the twodimensional QW plane in real space,…”

“…Upon switching off the control beam the switching action is reversed and the pattern returns to its original state T 1 . Switching times in the range of ∼100 ps are achievable [9].…”

“…[6][7][8]. The latter utilize the optical control of transverse optical patterns to achieve transistor-like switching performance [2,9]. Spontaneous formation of spatially extended patterns has been intensively studied during the past decades [10] with applications to different areas of science including formation of sand ripples and desert sand dunes [11], animal coat patterns such as zebra stripes [12,13], or geographic patterns in parasitic insect populations [14].…”

“…For linearly polarized pump excitation slightly above instability threshold, cross-linearly polarized resonant modes parallel and perpendicular to the pump's polarization plane constitute the basic instabilities [20], resulting in two-spot or four-spot patterns. Making use of this spatially anisotropic polariton scattering a reversible optical switching for orthogonal two-spot patterns can be realized that is triggered by a weak external control beam [9].…”