Patent ID: 8363990
Filing Date: 2013-01-29
Classification: B82Y,G02F,H01L,H01S,H03K

Abstract:
1. An optical set-reset (SR) latch, comprising: a first electroabsorption modulator which is initially electrically biased in a light-absorptive state wherein little, if any, light which is received into an input of the first electroabsorption modulator is transmitted to an output thereof; a second electroabsorption modulator which is optically connected to receive a first portion of the light transmitted through the first electroabsorption modulator with a second portion of the light transmitted through the first electroabsorption modulator being directed to a Q output of the optical SR latch to provide an indication of an optical logic state of the optical SR latch, and with the second electroabsorption modulator being electrically biased in a light-transmissive state wherein a majority of the first light portion received into the input of the second electroabsorption modulator is transmitted to the output thereof; a first waveguide photodetector optically connected to receive a Set light input and the first light portion after transmission through the second electroabsorption modulator, with the first waveguide photodetector being electrically connected to the first electroabsorption modulator, and with the first waveguide photodetector, upon detecting the Set light input, generating a photocurrent signal which temporarily changes the electrical biasing of the first electroabsorption modulator and switches the first electroabsorption modulator to the light-transmissive state so that the first light portion transmitted through the second electroabsorption modulator to the first waveguide photodetector increases in intensity to a light level which continues to generate the photocurrent signal after the Set light input diminishes in intensity, thereby latching the first electroabsorption modulator in the light-transmissive state; and a second waveguide photodetector optically connected to receive a Reset light input, with the second waveguide photodetector being electrically connected to the second electroabsorption modulator, and with the second waveguide photodetector, upon detecting the Reset light input, generating another photocurrent signal which temporarily changes the electrical biasing of the second electroabsorption modulator to switch the second electroabsorption modulator to the light-absorptive state wherein the first light portion transmitted through the second electroabsorption modulator to the first waveguide photodetector diminishes in intensity to a light level wherein the photocurrent signal generated by the first waveguide photodetector is insufficient to maintain the first electroabsorption modulator in the light-transmissive state so that the first electroabsorption modulator switches back to the light-absorptive state.