Design of a refractive index sensor based on surface soliton waveguides

Abstract

The design of an innovative integrated sensor based on superficial soliton waveguides is presented. This configuration is called a RISSOR: refractive-index surface-soliton sensor. The hybrid structure combines traditional rib waveguides with a superficial one realized by a superficial photorefractive soliton. Simulations are performed using a BPM numerical code. The sensitivity of the proposed device is based on the solitonic evanescent wave as well as the coupling between the rib and solitonic waveguides.

All-Optical Reinforcement Learning In Solitonic X-Junctions

“…We have numerically simulated the solitonic-waveguide X-junction using a well-tested FDTD numerical code 30 – 36 and monitored the energy transfer at the IR signal wavelength between channels according to the soliton writing power.…”

“…Calling A 1 and A 2 the light beams writing the waveguides and A 3 the signal beam, their nonlinear propagations are described by the following set of Helmholtz equations for a saturable nonlinearity: where ϵ NL is the nonlinear dielectric constant, E bias is an external electrical bias necessary for photorefractive screening solitons 30 and | A sat | 2 is the saturation intensity. We considered the A 1 beam at 527 nm and the A 2 beam at 532 nm in order to influence the material nonlinearity; the A 3 was instead set at 1.3 μm (the second telecom window), because it does not intervene in the nonlinearity, being just the transported passive signal; we have considered hyperbolic secant transverse profiles for the beams, propagating at a relative angle of 0.4°.…”

“…The experimental analysis of soliton X-junction performing reinforcement learning has been realized in lithium niobate crystals using the pyroliton 39 configuration. Lithium niobate is not the best nonlinear medium for this purpose, in term of speed, because soliton formation takes place in several minutes 30 : however, it has the big advantage of a fine control on the formation process. All measurements have been performed using Z-cut, congruent, striation-free lithium-niobate crystals (of dimensions 12×12×0.5 mm 3 ).…”

“…A single soliton (channel 1) was efficiently generated with 20 μW of power within 4 minutes (see Fig. 2a ), reaching a final hyperbolic waist 30 , 40 of 7 μm (similar to the input one). Its waveguiding behavior was tested injecting inside it a signal beam at 1.3 μm.…”

“…The material modification induced by solitons can be used as a waveguide to drive other signals inside, exactly like a pheromone trace drives ants along a specific direction. Since the 80’s 24 , 25 there has been a growing interest in the waveguiding properties of solitonic beams; among all, the photorefractive solitons represent the most practical ones because of the ultralow light power required for writing 26 , 27 waveguides 28 , interconnections 29 , sensors 30 and other devices.…”