An Improved Design for an All-Optical Flip-Flop Based on a Nonlinear 3-Sections DFB Laser Cavity

Abstract

A new all optical flip-flop based on a 3-sections nonlinear semiconductor DFB laser structure is proposed and simulated. The operation of the device does not require a holding beam. Electrical current injection into an active layer provides optical gain to the laser mode. The wave-guiding layer consists of a linear grating section centered between 2 detuned nonlinear grating sections. The average refractive index in the nonlinear sections is slightly higher than the refractive index of the middle section. A negative nonlinear refractive index coefficient exists along the nonlinear sections. In the "OFF" state, the DFB structure does not provide enough optical feedback to lase due to the detuned sections. At high light intensity in structure, "ON" state, detuning decreases and the DFB structure allows for a laser mode that sustains the decrease in detuning to exist. The nonlinearity is provided by direct photon absorption at the Urbach tail. Numerical simulations using GPGPU computing show nanoseconds transition times between "OFF" and "ON" states.

Simulations of a Novel All-Optical Flip-Flop Based on a Nonlinear DFB Laser Cavity Using GPGPU Computing

“…In [11], an all-optical ip-op based on a 3-section DFB laser structure is introduced. Two sections of the DFB structure are detuned from the middle part of the DFB structure.…”

“…The laser mode decays, and the device is switched "OFF". The device presented in this work has advantages over the device in [11]. In [11], 2 nonlinear sections are needed to achieve bistability, where in this work only one nonlinear section is required.…”

“…The device presented in this work has advantages over the device in [11]. In [11], 2 nonlinear sections are needed to achieve bistability, where in this work only one nonlinear section is required. Also, in [12], the device is switched "OFF" by XGM, but in this work, the device is switched "OFF" by detuning a section of the DFB structure, and the optical gain is not altered.…”