Picosecond all-optical switching in single-mode GaAs/AlGaAs strip-loaded nonlinear directional couplers

Abstract

Room-temperature all-optical switching has been achieved in single-mode strip-loaded nonlinear directional couplers with a GaAs/AlGaAs multiple quantum well guiding layer. For low input intensities nearly complete (1:3–1:5) cross coupling occurs, while at high input intensities switching occurs so that most (>3:1) of the light stays in the input guide. The effects of carrier diffusion are minimized by the use of picosecond pulses. The response time and the recovery time of the nonlinear directional couplers are measured with pump-probe experiments, and the origin of the nonlinearity is attributed to fast electronic effects.

All-optical Integrated Nonlinear Devices

“…Most of these demonstrations of NLDC operation have been performed in the near infrared with GaAs-AlGaAs multiple quantum well (MQW) structures [40][41][42][43][44], where the observed nonlinear effects are probably electronic in nature and due to an excitonic resonance in the MQW . Response times of less than 10 ps with recovery times of 4 ns (diffusion limited) and nonlinear coefficients of the order of 10 -5 cm 2 W -' have been measured both in planar [42,44] and strip-loaded guides [43] . Finlayson et al .…”

“…excitonic and band-filling) suffer from large absorption and thermal problems, and require involved fabrication technologies . Bistability and switching have been demonstrated in bulk devices, and a few results are available in guided-wave formats [14,16,[41][42][43][44][47][48][72][73][74] . Recently, nonlinear transmission measurements have been reported near 1 .…”

Nonlinear pulse propagation in long-period fiber gratings: theory and experiment

“…By appropriate manipulation, the governing equations can be written in terms of the electric field alone so that (7) where represents the electric field vector, is the speed of light, and is the permeability of free space. The polarization vector for a centrosymmetric crystal structure such as glass fibers is given by [24] (8)…”

“…At high intensities, the effects of self-phase and crossphase modulation perturb the linear mode coupling dynamics [3]. The resulting nonlinear coupling induces an intensity dependent phase change which can be used to tune the mode coupling on and off resonance; thereby creating a mechanism for all-optical switching [5]- [7].…”

Measurement of Pump-Induced Absorption and Refractive Index Changes in GaInAsP/InP Waveguides Using an Optical Loop Mirror Interferometer

“…[8][9][10] In these methods, it is difficult to measure simply and directly these changes on the basis of configurations and time resolution. Consequently, we apply an optical loop mirror interferometer proposed by Doran and Wood 11) to measure intensity-dependent refractive index changes.…”