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We design a lossless 8 × 8 Silicon Photonics (SiPh)/Indium Phosphide (InP) hybrid optical switch. The design consists of an 8-channel InP gain block for coupling to an 8 × 8 thermally tuned Mach-Zehnder interferometer-based Banyan switch in a passive SiPh platform. The gain block is an array of eight 1300 μm-long semiconductor optical amplifiers (SOAs). We experimentally verified the InP gain block while the SiPh chip is accounted by replacing it with a loss component. The SOA in line with the optical signal path provides a net gain larger than 25 dB to compensate for the inherently large insertion loss of the 8 × 8 SiPh optical switch. The total energy consumption of the hybrid optical switch in lossless operation mode is 10.44 pJ/bit at 12.5 Gb/s.

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A mode insensitive switch is proposed and experimentally demonstrated on a silicon-on-insulator platform using a balanced Mach–Zehnder interferometer structure with a mode insensitive phase shifter for on-chip mode division multiplexing interconnects. Switching the first three quasi-transverse electric (TE) modes, consuming less than 40 mW power is demonstrated. The whole system exhibits approximately − 2 , − 3.7 , and − 5.2 d B insertion loss for the TE0, TE1, and TE2 modes at 1550 nm, respectively. The corresponding crosstalk is less than − 8.6 ( − 9 ) , − 8 ( − 10.3 ) , and − 10 d B ( − 10.3 d B ) within the wavelength range of 40 nm (1535–1575 nm) for the cross (bar) states, respectively. The extinction ratios (ERs) for the cross (bar) states are 20.1 (19.5), 22.8 (33.7), and 15.4 dB (18.1 dB) for the TE0, TE1, and TE2 modes at 1550 nm, respectively. The payload transmission is also conducted using non-return-to-zero pseudorandom binary sequence (PRBS)-31 data signals at 10 Gb/s for single-mode transmission and simultaneous three-mode transmissions. For all the scenarios, open eyes are observed.

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The design, fabrication, and characterization of an 8 × 8 lossless optical switch, based on semiconductor optical amplifier (SOA) gates, is reported. It comprises three stages of 2 × 2 switches into an 8 × 8 Banyan switch, for a total of 48 SOAs. Three SOAs on each optical path provide gain to compensate for on-chip and fiber coupling loss, thereby making the optical switch lossless. All 64 optical paths demonstrate error-free 10 Gbps NRZ PRBS-31 transmission with at least 30 dB signal-to-noise ratio and less than 0.9 dB power penalty.

A quaternary lattice-matched layer structure based on employing a bilayer barrier for improving the carrier confinement in the channel of enhancement-mode metal-face c-plane wurtzite AlInGaN/GaN hetero-structure field effect transistors (HFETs) is for the first time proposed. Using the commercial self-consistent Poisson-Schrödinger solver Nextnano, electronic properties of the proposed hetero-structure, including the sheet charge density and carrier confinement on the GaN side of the hetero-interface, are evaluated. Based on these evaluations, it is shown that while the proposed layer structure substantially improves the carrier confinement in the GaN channel layer, it also upholds the merits of employing a lattice-matched barrier towards achieving an enhancement-mode operation (i.e., in the absence of the piezoelectric effect). According to these simulations, in terms of maintaining the required positive threshold-voltage for the enhancement-mode operation, it is also shown that the proposed layer structure substantially outperforms the quaternary AlInGaN/GaN HFETs employing a thin AlN spacer layer.

In this work, we experimentally demonstrate a four-mode polarization/mode insensitive 3-dB coupler based on an adiabatic coupler. The proposed design works for the first two transverse electric (TE) modes and the first two transverse magnetic (TM) modes. Over an optical bandwidth of 70 nm (1500 nm to 1570 nm), the coupler exhibits at most 0.7 dB insertion loss with a maximum crosstalk of -15.7 dB and a power imbalance not worse than 0.9 dB. A multimode photonic switch matrix using this optical coupler is proposed simultaneously exploiting wavelength division multiplexing (WDM), polarization division multiplexing (PDM), and mode division multiplexing (MDM). Based on the coupler experimental measurements, the switching system loss is estimated to be 10.6 dB with crosstalk limited by the MDM (de)multiplexing circuit.