An optimized SOI 2×2 multimode interference (MMI) coupler is designed by use of the particle swarm optimization (PSO) algorithm. Finite Difference Time Domain (FDTD) simulation shows that, within a footprint of 9.4×1.6 μm.sup.2, <0.1 dB power unbalance and <1 degree phase error are achieved across the entire C-band. The excess loss of the device is <0.2 dB.

A method and mode conversion waveguide system for converting a mode of a light is provided. The light is sent through a single mode waveguide, wherein the light has a first mode while traveling through single mode waveguide. The light is sent from the single mode waveguide into a multimode interference region having connected to the single mode waveguide. The light is reflected with a cavity within the multimode interference region in a manner that causes the light to propagate away from the single mode waveguide. The light is output from multimode interference region, wherein the light has a second mode.

A large-scale single-photonics-based optical switching system that occupies an area larger than the maximum area of a standard step-and-repeat lithography reticle is disclosed. The system includes a plurality of identical switch blocks, each of is formed in a different reticle field that no larger than the maximum reticle size. Bus waveguides of laterally adjacent switch blocks are stitched together at lateral interfaces that include a second arrangement of waveguide ports that is common to all lateral interfaces. Bus waveguides of vertically adjacent switch blocks are stitched together at vertical interfaces that include a first arrangement of waveguide ports that is common to all vertical interfaces. In some embodiments, the lateral and vertical interfaces include waveguide ports having waveguide coupling regions that are configured to mitigate optical loss due to stitching error.

An optical multiplexer that extends a transmission bandwidth of light is achieved. The present invention provides an optical multiplexer constructed of a multimode waveguide to which two single mode input waveguides are connected at a distance and two single mode output waveguides connected at a distance to a surface opposite a surface to which the input waveguides of the multimode waveguide are connected, in which a width of the multimode waveguide is smaller than widths of the two input waveguides plus a distance between the input waveguides, and the input waveguides are connected to the multimode waveguide and the multimode waveguide is connected to the output waveguides via tapered waveguides, respectively.

In an integrated optical device, squeezed light is used internally to effectively increase an optical modulation effect. One exemplary device operates by squeezing the light at the input, then sending it through an electro-optic stage where its phase picks up the signal of interest, and finally anti-squeezing it to obtain a displaced coherent state. Thus the displacement is amplified by the level of squeezing that is achieved inside the device and it is thereby less sensitive to loss. Since this device behaves simply as an electro-optic modulator, albeit one with an exponentially enhanced sensitivity, no extra considerations are needed to integrate the modulator into a system. Such devices can be operated as modulators or as sensors, and can make use of optical phase shift effects other than the electro-optic effect.

A demultiplexer for use in a wavelength division multiplexed system. The demultiplexer comprises: an input waveguide, configured to receive a wavelength division multiplexed signal; a demultiplexing element, configured to demultiplex the multiplexed signal received from the input waveguide into a plurality of multi-mode demultiplexed signal components; a multi-mode output waveguide, the multi-mode output waveguide being coupled to the demultiplexing element and configured to receive one of the multi-mode demultiplexed signal components; and a splitter, coupled to the multi-mode output waveguide, and configured to split the received multi-mode demultiplexed signal component into two single-mode outputs.

Configurations for a modal interference device used for wavelength locking are disclosed. The modal interference device may be an interference device that includes an input waveguide, an interference waveguide, and an output waveguide. A fundamental mode of light may be launched into the input waveguide and the interference waveguide may receive the fundamental mode and generate a higher order mode of light, where the two modes of light may be superimposed while propagating through the interference waveguide. The two modes of light may be received at an output waveguide that collapses the two modes into a single mode and generates an output signal corresponding to the interference between the two modes of light. The output signal may be used to wavelength lock a measured wavelength to a target wavelength. The multiple output waveguides may produce output signals that have dead zones that do not align with one another for any wavelength in the wavelength range of interest.

A photonic integrated circuit comprises an optical deinterleaver, including an input region, a dispersive region, and at least two output regions. The input region is adapted to receive an input optical signal including a plurality of channels. The dispersive region is optically coupled to the input region to receive the input optical signal. The dispersive region includes an inhomogeneous arrangement of a first material and a second material to structure the dispersive region to separate the input optical signal into a plurality of multi-channel optical signals, including a first multi-channel optical signal and a second multi-channel optical signal. The at least two output regions, include a first out region and a second output region optically coupled to the dispersive region. The first output region is positioned to receive the first multi-channel optical signal and the second output region is positioned to receive the second multi-channel optical signal.

Embodiments herein relate to a photonic integrated circuit (PIC). The PIC may include a transmit module and a receive module. An optical port of the PIC may be coupled to the transmit module or the receive module. A semiconductor optical amplifier (SOA) may be positioned in a signal pathway between the optical port and the transmit module or the receive module. Other embodiments may be described and/or claimed.

A photonics integrated circuit includes a first waveguide and a second waveguide. A portion of the first waveguide has a first cladding with a first refractive index. The second waveguide includes a second cladding with a second refractive index different from the first refractive index. Also disclosed is a test circuit for a photonics integrated circuit. The test circuit can be used to determine waveguide losses, and used to tune the waveguide losses.