Abstract: An entirely passive all-optical device, referred to as an optical hard limiter, consists of alternating layers of materials having oppositely signed Kerr coefficients and substantially different linear indices of refraction, wherein the higher linear index material has the negative Kerr coefficient and the lower linear index material has the positive Kerr coefficient. The optical device has two distinct transmittance curves. Various optical devices and systems can be built from such optical hard limiters.

Abstract: Various optical logic devices are formed using stable, non-absorbing optical hard limiters. These optical logic devices are able to process information optically without the need to convert the information to an electronic form for processing electronically.

Abstract: Analog noise is subtracted from an optical communication channel using stable, non-absorbing optical hard limiters. A reference signal B is combined with a control signal of intensity I2 through a 3 dB optical coupler to form a first combined signal having an intensity substantially equal to (B/2 +I1). The first combined signal is processed by a first optical hard limiter to form a reflected signal having an intensity substantially equal to (I1−B/2). An information signal A is combined with a bias signal of intensity I2 through a 3 dB optical coupler to form a second combined signal. The reflected signal and the second combined signal are combined through a 3 dB optical coupler to form a third combined signal having an intensity substantially equal to 0.5(I1−B/2+A/2+I1). The third combined signal is processed by a second optical hard limiter to form a transmitted signal having an intensity substantially equal to 0.5(A−B). 12 is substantially equal to two times I1.

Abstract: Optical automatic gain control (AGC) is accomplished using stable, non-absorbing optical hard limiters and various optical logic gates derived therefrom. The AGC mechanism preserves the ratios between signal levels and provides an adjustable amount of gain.

Abstract: An optical sampler based on stable, non-absorbing optical hard limiters includes an optical feedback loop for storing an optical signal in optical form. The optical feedback loop includes appropriate components for amplifying/reproducing the stored optical signal. The optical sampler outputs the stored optical signal.

Abstract: An optical switching device based on stable, non-absorbing optical hard limiters optically switches optical information from an input to a number of outputs based upon address information contained in the optical information. The optical switching device optically detects the location of the address bits in the optical information, optically samples the address bits, optically decodes the sampled address bits, optically activates an output based upon the decoded address bits, and optically outputs the optical information over the activated output.