A novel electro-optic (EO) modulator based on graphene on silicon (GoS) dual-slot waveguide is proposed, utilizing the electro-absorption and electro-refraction effect of graphene. The optical mode in the waveguide can interact strongly with the upper graphene layer due to the enhancement of light intensity and poor mode confinement in the nanometer slot. The real part and imaginary part of effective modal index relate to the optical propagation phase and attenuation, respectively. Electro-absorption and electro-refraction modulators can be realized by reasonably tuning the chemical potential of graphene through an applied gate voltage. The geometric parameters of the GoS waveguide are well optimized. Simulation results show the phase shift can be linearly tuned from 0 to π by changing the gate voltage from 1 to 5.4 V for a 70 μm-long GoS dual-slot waveguide. When this waveguide is used as electro-absorption modulator, the modulation depth and insertion loss are 25 dB and 0.09 dB, respectively. The 3-dB bandwidth is estimated to be 79.6 GHz. The power consumption is ~0.94 pJ/bit and ~1.42 pJ/bit for the electro-refraction and electro-absorption modulation, respectively. The FoM (modulation depth/insertion loss) is as high as 273. This GoS dual-slot waveguide modulator with merits of footprint-compact, energy-efficient and CMOS compatible has potentials in on-chip optical interconnections.

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.

In this paper, electro-absorption variable optical attenuators (VOAs) have been designed and fabricated on silicon-on-insulator material with a 3 μm thick top silicon layer. We have simulated the impact of doping distance, doping width, doping depth, doping concentration, and doping length on VOA’s power consumption at 20 dB attenuation. We have found that the power consumption of VOA at 20 dB attenuation will decrease as the doping distance and doping width get smaller, while the doping depth and doping concentration get larger. We have further demonstrated that the power consumption can also be reduced by increasing the doping length and by taking a series structure theoretically. In this paper, VOAs with different doping structures, doping distances, doping widths, and doping lengths have been fabricated, and the tested results have verified our theoretical analysis. With doping distance of 8 μm, doping width of 15 μm, doping length of 1 cm, doping concentration of $1\times {10}^{19}{\mathrm{cm}}^{-3}$, and doping depth of 0.9 μm, the power consumption of the series VOA at 20 dB attenuation is 470 mW, and the rising/falling time is 54 ns/49.5 ns.

We experimentally demonstrate efficient light emission enhancement from Si with Er/O co-implanting coupled to 2-D hexagonal photonic crystal (PC) double-heterostructure microcavity fabricated on silicon-on-insulator. A single sharp resonant peak with 1552.2 nm communication wavelength dominates the photoluminescence (PL) spectrum and 35-fold PL intensity enhancement is obtained compared to the case of identically implanted silicon-on-insulator wafer at room temperature. The obvious red-shift and degraded Q-factor of resonant peak are present with the excitation power increasing, and the maximum measured Q-factor of 3829 is found at 1.5 mW power. The resonant peak is observed to shift depending on the structural parameters of PC.