All-Optical Logic Based on Ultrafast Gain and Index Dynamics in a Semiconductor Optical Amplifier

Abstract

Abstract-We investigate nonlinear carrier dynamics in a multiquantum-well semiconductor optical amplifier (SOA) in the context of ultrafast all-optical logic. A rate-equation model is presented that accounts for two-photon absorption, free-carrier absorption, self-and cross phase modulation, carrier heating, spectral, spatial hole burning, and self-and cross polarization modulation. The nonlinear refractive index dynamics is investigated theoretically and experimentally. We find nonlinear phase changes larger than radians, which recovers on a timescale in the order of 1 ps. We also investigate a nonlinear AND gate that consists of an SOA that is placed in an asymmetric Mach-Zehnder interferometer. We show that the gate can be operated using 800-fJ optical pulses with duration of 200 fs while having a contrast ratio larger than 11 dB.Index Terms-Optical logic, optical signal processing ultrafast carrier dynamics, semiconductor optical amplifier.

Ultracompact all-optical full-adder and half-adder based on nonlinear plasmonic nanocavities

“…The total size of this function device is determined to be lower than 15 μm, which is reduced by three orders of magnitude compared with previously reported results [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. The intensity contrast ratio between the two output logic states "1" and "0" was larger than 27 dB, which is among the highest values reported to date [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. This work provides a platform for studying nonlinear optics and quantum optics, while, at the same time, paves a way to realize ultrahigh-speed signal computing chips.…”

“…The logic operations of the full-and half-adders were performed based on the signal-light induced plasmonic-nanocavity-modes shift by using the third-order nonlinear optical Kerr effect. A large third-order optical nonlinearity was obtained for the multicomponent nanoAu:(IR140:MEH-PPV) cover layer on account of tremendous nonlinearity enhancement related to resonant excitation, slow-light effect, and field enhancement effect provided by plasmonic nanocavity modes, which cause an ultralow operating threshold power of 300 μW (corresponding to a threshold operating intensity of 7.8 MW/cm 2 ), reduced by two orders of magnitude compared with previous reports [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. The total size of this function device is determined to be lower than 15 μm, which is reduced by three orders of magnitude compared with previously reported results [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38].…”

“…Therefore, excellent logic operations of full-adder were achieved with an ultralow operating threshold intensity of 7.8 MW/cm 2 , which is reduced by two orders of magnitude compared with previous reports [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. The feature size of this function device is determined to be <15 μm, which is reduced by three orders of magnitude compared with previously reported results [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. The intensity contrast ratio between the two output logic states "1" and "0" was larger than 27 dB, which is among the highest values reported to date [20][21][22][23][24][25][26]…”

“…Subsequently, plenty of schemes have been proposed to demonstrate nanoscale all-optical logic adder based on third-order nonlinear optical effects (including cross-phase modulation) [20][21][22][23][24], cross-gain modulation [25][26][27], and four wave mixing [28][29][30][31][32], or linear interference mechanism [33][34][35][36]. The extremely high accuracy requirements for light paths in the linear interference configuration and relatively small thirdorder nonlinear susceptibility of conventional materials result in a low intensity contrast ratio of <10 dB between output logic states "1" and "0" [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Moreover, a large threshold operating intensity of several GW/cm 2 order was required for basic all-optical logic adder devices based on third-order nonlinear optical effects [20-32, 37, 38].…”

Wavelength dependent ultrafast gain and phase dynamics in bulk SOAs over wide gain region

“…The understanding of ultrafast gain and phase dynamics in semiconductor optical amplifiers (SOAs) is very important for high-speed all-optical signal processing because SOA-based cross-gain and cross-phase modulations are the two fundamental nonlinear mechanisms utilized as wavelength conversion, logic gates and so on (Dorren et al 2004). The modulation of probe intensity or phase in a SOA excited by ultrashort pump pulses is widely experimentally researched (Dorren et al 2004;Hall et al 1994;Mark and Mørk 1992;Mørk and Mecozzi 1996).…”