Optical logic gates are constructed from Mach-Zehnder interferometer (MZI) optical circuits. A multi-mode interference (MMI) splitter divides a continuous-wave input into two branches of the interferometer. Each branch has a semiconductor optical amplifier (SOA). When a logic input having a logic-high power level is applied to one of the SOA's, cross-phase modulation occurs in the SOA. The phase shift increases through the SOA. The branch coupled to the logic input has a relative phase shift of π compared with the other branch. When two branches with the π phase difference are combined, destructive interference occurs, producing a logic low. An MMI combiner or an equivalent phase shifter is used to combine the two branches. The MMI splitter adds a phase shift of π/2 to the upper branch but not to the lower branch, while the MMI combiner also adds π/2 shifts.

All optical logic using cross-phase modulation amplifiers and mach-zehnder interferometers with phase-shift devices

A multimode interference device and method of making the same comprises at least one input port, at least one output port, a multimode interference region separating the input port from the output port, and at least one subregion in the multimode interference region, wherein a self-image length within the multimode interference region is reduced by a factor that is approximately equal to one plus a number of subregions configured in the multimode interference region, wherein the at least one subregion is configured to have an effective width and effective refractive index running longitudinally through the multimode interference region. Additionally, the subregion may comprise at least one slot.

Slotted multimode interference device

An optically sampling device optically samples an optical analog signal using a sampled signal having a predetermined sampling frequency, and outputs control light having a pulse train of an optically sampled optical analog signal. A signal generating device generates a pulse train of signal light which is synchronized with the sampled signal. An optical encoding device optically encodes the pulse train of the signal light according to the control light, by using optical encoders each including nonlinear optical loop mirrors, and outputs pulse trains of optically encoded signal light from said optical encoders, respectively. An optically quantizing device performs optical threshold processing on the pulse trains of optically-encoded signal light to optically quantize them, by using at least one of optical threshold processors each of which is connected to each of said optical encoders and includes a nonlinear optical device, and outputs optically quantized pulse trains as optical digital signals.

Optical Signal Processing Device For A/D Converter Including Optical Encoders With Nonlinear Loop Mirrors

An optical wavelength converter converts an optical input signal having a first wavelength into an optical output signal having a second wavelength The wavelength converter includes a saturable absorber switch having a control beam waveguide and an input waveguide The converter further includes a first input coupled to the control beam waveguide and adapted to receive the optical input signal, and a second input coupled to the input waveguide and adapted to receive a second optical signal having the second wavelength from an optical source

Optical wavelength converter

An all-optical logic gates comprises a nonlinear element such as an optical resonator configured to receive optical input signals, at least one of which is amplitude-modulated to include data. The nonlinear element is configured in relation to the carrier frequency of the optical input signals to perform a logic operation based on the resonant frequency of the nonlinear element in relation to the carrier frequency. Based on the optical input signals, the nonlinear element generates an optical output signal having a binary logic level. A combining medium can be used to combine the optical input signals for discrimination by the nonlinear element to generate the optical output signal. Various embodiments include all-optical AND, NOT, NAND, NOR, OR, XOR, and XNOR gates and memory latch.

All-optical logic gates using nonlinear elements—claim set V

An optical inverter (10) that uses a saturable absorber (28) to distinguish between a logical one and a logical zero. A low power laser (18) generates an optical beam that is split into a first beam that propagates among a first beam path (24) and a second beam that propagates along a second beam path (26). The saturable absorber (28) is an optical switch that is positioned in the first beam path (24), and is switched from an opaque mode to a transparent mode when it receives an optical input signal. The first beam and the second beam are recombined as an optical output beam in an optical combiner (30). The first beam path (24) and the second beam path (26) have a length relative to each other such that the first and second beams are 180° out of phase when they reach the optical combiner (30). Therefore, if the saturable absorber (28) is switched to the transparent mode, the first and second beams combine destructively and the optical output beam is dark, or a logical zero. When the saturable absorber (28) is in the opaque mode, the first beam is blocked so that the optical output beam is the second beam, providing a logical one. A second saturable absorber (34) can be provided to receive the optical output beam from the combiner (30) to absorb residual light when the output beam is dark. Additionally, an optical amplifier (36) can be provided to receive the optical output beam from the combiner (30) to amplify the optical output beam to a consistent, predetermined output level.

Saturable absorber based optical inverter

Theoretical modeling of InP coupled-quantum-well electroabsorptive and electrorefractive modulators is presented. Key mathematical transformations are developed that allow efficient computation of electrorefraction for a complex multiparameter coupled quantum well structure. The model is realized in the Mathematica platform and is used to simulate the impact of well and barrier composition and thickness on Mach-Zehnder modulator performance. The advantage of using coupling between quantum wells is quantified and in addition, it is shown that linewidth broadening is a key input to the model and has a critical impact on modulator performance. The model is compared to experimental data from phase modulators and Mach-Zehnder intensity modulators.

Electrorefractive Coupled Quantum Well Modulators: Model and Experimental Results

An integrated optoelectronic device (1) includes a substrate(4), at least one optoelectronic component (2) provided on the substrate (4), and a waveguide (9a ... 9n) provided on the substrate (4) and optically connected to the at least one optoelectronic component (2). The waveguide (9a ...9n) is made of a sol-gel glass. A method for making the integrated optoelectronic device (1) includes the steps of providing a substrate (4), providing at least one optoelectronic component (2) on the substrate (4), and providing at least one sol-gel glass waveguide (9a ... 9n) on the substrate (4) and optically connected to the at least one optoelectronic component (2).

Integrated optoelectronic device and method for making same

An optical quantizer (10) that employs a chain of optical thresholding devices (16) positioned in the propagation path of an optical input beam (12) to be quantized. Each optical thresholding device (16) saturates and turns transparent if the intensity of the optical beam (12) that impinges it is above a predetermined threshold level designed into the device (16). If the input beam (12) saturates the optical thresholding device (16), the device (16) outputs an indicator signal (22) identifying the saturation. The input beam (12) propagates through the optical thresholding device (16) with some attenuation caused by the saturation, and impinges subsequent optical thresholding devices (16) in the chain. Eventually, the attenuation of the input beam (12) caused by the multiple saturations will decrease the beam intensity below the threshold level of the next optical thresholding device (16). The number of indicator signals (22) gives an indication of the intensity of the input beam (12). The optical thresholding devices (16) can provide optical or electrical indicator signals (22) depending on the type of thresholding device (16) used.

Repetitive absorptive thresholding optical quantizer

A single-electrode, push-pull semiconductor PIN Mach-Zehnder modulator (10) that includes first and second PIN devices (12, 14) on a substrate (16). Intrinsic layers (22, 28) of the devices (12, 14) are the active regions of two arms (50, 52) of a Mach-Zehnder interferometer. An outer electrode (38) is connected to the N layer (24) of the first PIN device (12) and a center electrode (40) is connected to the P layer (20) of the first PIN device (12). An outer electrode (42) is connected to the P layer (26) of the second PIN device (14) and the center electrode (40) is connected to the N layer (30) of the second PIN device (14). An RF modulation signal biases the PIN devices (12, 14) in opposite directions and causes the index refraction of the intrinsic layers (22, 28) to change in opposite directions to give a push-pull modulation effect.

Elizabeth T. Kunkee

Papers

Saturable absorber based optical inverter

Electrorefractive Coupled Quantum Well Modulators: Model and Experimental Results

Integrated optoelectronic device and method for making same

Repetitive absorptive thresholding optical quantizer

Single-electrode push-pull configuration for semiconductor PIN modulators