Optical generation of UWB pulses utilizing Fano resonance modulation

In this paper,we reported an integrated method to generate ultra-wideband(UWB)pulses of different orders based on a reconfigurable silicon micro-ring resonator-coupled Mach–Zehnder interferometer.Under proper operating conditions,the device can produce Fano resonances with a peak-to-valley extinction ratio of above 20 dB.UWB monocycle and doublet signals with picosecond pulse widths are produced when the microring resonator is modulated by square and Gaussian electrical pulses,respectively.With our Fano resonance modulator on silicon photonics,it is promising to foresee versatile on-chip microwave signal generation.

High-speed silicon microring modulator at the 2μm waveband with analysis and observation of optical bistability

Recently,significantly raised interests have emerged for the 2μm waveband as an extended new window for fiber optic communication.Much research progress has been made on the photonic integrated circuits for the 2μm waveband,especially on the CMOS-compatible silicon-on-insulator wafer.In this work,a silicon integrated microring modulator(MRM)with record high-speed performances at the 2μm waveband was demonstrated.An L-shaped PN junction was specially designed for 2μm to achieve a high modulation efficiency with V_(π)L of 0.85V·cm.The measured 3 dB bandwidth is 18 GHz,supporting up to 50 Gbps signaling at 2μm.Additionally,optical bistability induced by the thermo-optical effect and nonlinear effects was analyzed theoretically and observed experimentally in the 2μm MRM for the first time to our knowledge.Nonlinear coupled mode theory and the Runge-Kutta method were used to simulate the behaviors of bistability in the 2μm MRM.The simulation and experimental results indicate that,when the MRM is launched by a high optical power,the distorted resonant spectrum under an optical bistable state deteriorates the modulation efficiency and signal performances.This work breaks the record of high-speed silicon MRM at 2μm,drawing a promising prospect for the silicon photonic integration and high-speed interconnection at the 2μm waveband,and it provides the referenceable analysis of optical bistability,which guides the design and experimental investigation of 2μm MRM.

Wavelength-mode pulse interleaver on the silicon photonics platform

We report an 8-channel wavelength-mode optical pulse interleaver on a silicon photonic chip.Wavelength-and mode-division multiplexing techniques are combined to increase the repetition rate of the pulses without adding the complexity of a single dimension.The interleaver uses a cascaded Mach–Zehnder interferometer architecture as a wavelength-division(de)multiplexer,an asymmetric directional coupler as a mode(de)multiplexer,and various lengths of silicon waveguides as delay lines.A pulse sequence with a time interval of 125 ps is implemented with the repetition rate being eight times that of the initial one.The demonstrated wavelength-mode multiplexing approach opens a new route for the generation of high-speed optical pulses.

Silicon mode-loop Mach-Zehnder modulator with L-shaped PN junction for 0.37 V·cm V_(π)L high-efficiency modulation

Optical signaling without a high voltage driver for electric-optic modulation is in high demand to reduce power consumption,packaging complexity,and cost.In this work,we propose and experimentally demonstrate a silicon mode-loop Mach–Zehnder modulator(ML-MZM) with record-high modulation efficiency.We used a mode-loop structure to recycle light twice in the phase shifter.With an L-shaped PN junction,a comparably large overlap between the PN junction and optical modes of both TE0 and TE1 was achieved to lower the driving voltage or decrease the photonic device size.Proof-of-concept high-efficiency modulation with low VπL of 0.37 V · cm was obtained.Subvoltage Vπcan be realized with a millimeter’s length phase shifter by this scheme,which makes the realization of CMOS-compatible driverless modulation highly possible.40 Gb/s signaling with a bit error rate below the 7% forward-error-correction threshold was then demonstrated with the fabricated ML-MZM,indicating great potential for high-speed optical communication.