Abstract: A photonic time-slot interchanger with fiber-loop delay-line memories is provided with multistage, cascade-structured integrated optical switches in the write-in, store and circulate and read-out functions to provide improved signal-to-crosstalk ratios and control tolerances, and to increase significantly the number of time slots supported by the improved interchanger.

Abstract: An integrated optical 2.times.2 changeover switch having four waveguide directional couplers has two wageguide directional couplers cascaded in each path from a port on one side to a port on the other side. Only two electrodes control the switch states of all four couplers. Crosstalk is guided to unused ports of the directional couplers. The extinction ratio is the sum of the extinction ratios of the cascaded couplers in its path. Additional waveguide couplers can be placed in the path of the crosstalk to improve the extinction ratio further.

Abstract: A 1.times.2 integrated optical switch is a monolithic integration of two high-extinction cascaded coupled-waveguide modulators, one of said modulators being a bar-type modulator to provide a straight-through path and the second being a cross-type to provide a cross-over path between input and outputs. The primary and secondary waveguides in each section of the cross-type and the bar-type modulators respectively serve to dissipate unwanted crosstalk. A 2.times.1 integrated optical switch is obtained by reversing the waveguide patterns. The addition of waveguide bends to ends of the secondary waveguides of each modulator results in a bidirectional 1.times.2/2.times.1 integrated optical switch.

Abstract: An integrated optical intensity modulator is constructed by cascading individual waveguide directional coupler sections, each having a primary and secondary waveguide and a pair of uniform electrodes. A modulator normally operating in an OFF state has a bar-type structure such that the primary waveguides form one complete and straight waveguide. An input optical signal applied to this modulator propagates straight through the device. Another modulator structure normally operating in an ON state has a cross-type configuration which operates such that the coupled signal from one coupler section serves as the input signal for a next section. Each modulator is driven from its normal state into an opposite state by applying a voltage to the electrodes for inducing changes in the refractive index profile. A plurality of the optical modulators are fabricated in parallel on an integrated optical wafer to form a high-density optical gate array.

Abstract: An optical space switch architecture is constructed from electro-optical gate arrays each comprised of a plurality of ultra-high-extinction optical intensity modulators which are in turn fabricated from cascaded directional waveguide coupler sections. Input optical signals are processed by 1-to-N passive splitter circuits for providing interim optical signals which are routed to the optical gtate arrays. Each interim signal is processed by an optical modulator and emerges, depending upon the activation of the particular gate, in either an ON or OFF state. The optical signals emerging from the gate arrays are routed to N-to-1 passive combiner circuits according to a connectivity configuration whereupon the incoming signals are combined before appearing at the output ports of the combiner circuits. Optical amplifiers are incorporated into the splitter and combiner circuits if power compensation is required.

Abstract: A hybrid design for rectangularly configured integrated optical matrix switches uses both 2.times.2 optical changeover switches and 2.times.2 optical shift switches to achieve significant reduction of crosstalk accumulation for a strictly nonblocking switch architecture. The 2.times.2 optical shift switches are novel two-stage switches which allow two connection paths to bypass each other with very little crosstalk in the crossover state. A crossbar matrix switch uses 2n 2.times.2 optical changeover switches in the outer stages and n.sup.2 -2n optical shift switches in the intermediate stages.