Wavelength division (de)multiplexing (WDM) device is a crucial component for optical transmission networks. In this paper, we demonstrate a 4 channel WDM device with a 20 nm wavelength spacing on silica based planar lightwave circuits (PLC) platform. The device is designed using an angled multimode interferometer (AMMI) structure. Since there are fewer bending waveguides than other WDMs, the device footprint is smaller, at 21 mm × 0.4 mm. Owing to the low thermo-optic coefficient (TOC) of silica, a low temperature sensitivity of 10 pm/°C is achieved. The fabricated device exhibits high performance of an insertion loss (IL) lower than 1.6 dB, a polarization dependent loss (PDL) lower than 0.34 dB, and the crosstalk between adjacent channels lower than −19 dB. The 3 dB bandwidth is 12.3∼13.5 nm. Moreover, the device shows a high tolerance with a sensitivity of central wavelength to the width of multimode interferometer < 43.75 pm/nm.

A high-Q-factor tunable silica-based microring resonator (MRR) is demonstrated. To meet the critical-coupling condition, a Mach–Zehnder interferometer (MZI) as the tunable coupler was integrated with a racetrack resonator. Then, 40 mW electronic power was applied on the microheater on the arm of MZI, and a maximal notch depth of about 13.84 dB and a loaded Q factor of 4.47 × 10⁶ were obtained. The proposed MRR shows great potential in practical application for optical communications and integrated optics.

In this paper, a polymer/silica hybrid waveguide thermo-optic variable optical attenuator (VOA), covering the O-band, is demonstrated. The switch is fabricated by simple and low-cost direct ultraviolet (UV) lithography. The multimode interferences (MMIs) used in the Mach–Zehnder interferometer (MZI)-VOA are well optimized to realize low loss and large bandwidth. The VOA shows an extinction ratio (ER) of 18.64 dB at 1310 nm, with a power consumption of 8.72 mW. The attenuation is larger than 6.99 dB over the O-band. The rise and fall time of the VOA are 184 μs and 180 μs, respectively.

In this paper, ultrahigh-Q factor racetrack microring resonators (MRRs) are demonstrated based on silica planar lightwave circuits (PLCs) platform. A loaded ultrahigh-Q factor Q_load of 1.83 × 10⁶ is obtained. The MRRs are packaged with fiber-to-fiber loss of ~5 dB. A notch depth of 3 dB and ~137 pm FSR are observed. These MRRs show great potential in optical communications as filters. Moreover, the devices are suitable used in monolithic integration and hybrid integration with other devices, especially in external cavity lasers (ECLs) to realize ultranarrow linewidths.

A multimode reconfigurable non-blocking thermo-optical switch array is proposed and experimentally demonstrated based on silica platform. Four mode (de)multiplexers and a 4×4 non-blocking thermo-optical switch are integrated monolithically. Four mode lights, including E ₀₀ , E ₁₀ , E ₂₀ , and E ₃₀ , are generated and transported back fundamental mode before launching into switch array. The lights in switch are able to different outputs. The 2×2 optical switch unit is a balanced Mach-Zehnder interferometer based on a directional coupler structure, with heated electrodes above two modulation arms. At 1550 nm, with mode (de)multiplexers introduced, the average fiber to fiber losses are increased to 3.05 dB ± 0.31 dB and 2.75 dB ± 1.50 dB from 2.69 dB ± 1.18 dB and 2.68 dB ± 0.93 dB in the “all-cross” and “all-bar” states, respectively. The crosstalk is deteriorated to –12.62 dB from –19.37 dB at 1550 nm. The hybrid reconfigurable system on chip can work among C-band. The chip proves the commercial possible of multimode reconfigurable system on silica platform. Based on photonics integrated circuit platform, compact and large-scale multimode system on chip is promising.

Optical switch is a promising technology for high bandwidth communication in data centers. In this letter, we demonstrate a $3\times 3$ switch with p-i-n phase shifters. With pull-push configuration, the average on-chip insertion losses at 1550 nm of $3\times 3$ switch are 3.38 ± 0.7 dB and 4.04 ± 1.42 dB for “all-cross” and “all-bar” states, respectively. The optical crosstalk is lower than −10.57 dB from 1530 to 1565 nm for the worst case. The measured rise/fall time of the switch upon electrical tuning is 2.4(8.0) ns.