Design and demonstration of ultra-high-Q silicon microring resonator based on a multi-mode ridge waveguide.

We present the design and experimental demonstration of the ultra-high-Q-factor silicon microring resonator based on a multi-mode ridge waveguide. The multi-mode ridge waveguide is designed to decrease the propagation loss and to improve the Q factor. The ultra-high Q factor of 1.1×106 is experimentally demonstrated, with the free spectrum range of 0.208 nm. The single-mode ridge waveguide is used in the coupling region to reduce the dimension of the microring resonator, and the bend radius is only 20 µm. To precisely control the resonance wavelength, a small heater is implemented on the silicon microring resonator with the tuning efficiency of 7.1 pm/mW. The degenerate four-wave mixing of the silicon microring resonator is investigated, and the conversion efficiency is measured to be -15.5 dB without optimizing the dispersion of the microring resonator and carriers extraction.

Silicon micro-ring tunable laser for coherent optical communication.

A compact external cavity tunable laser based on a silicon hybrid micro-ring resonator is demonstrated. A theoretical model is also employed for design and analysis of the wavelength tuning performance of the device. In this model, the gain section of the device is simulated by a conventional multimode rate equation model, whereas all rest passive sections are modeled by the frequency domain method. Experimental results have shown that the output power of this device can reach 29 mW, with a linewidth less than 150 kHz. The tuning range is more than 17 nm in C-band with 60 dB side-mode-suppression-ratio (SMSR). This device shows a comparable performance with the commercial narrow linewidth laser as the source in coherent transmission systems.

Cost-effective coherent PON using silicon Mach-Zehnder modulator and digital carrier regeneration.

We propose a cost-effective coherent passive optical network (PON) by employing the linear silicon Mach-Zehnder modulator (MZM) with computationally-efficient digital signal processing (DSP). The proposed PON adopts the intensity modulation and coherent detection scheme with discrete multi-tone (DMT) signal to achieve both high spectral efficiency (SE) and receiver sensitivity. Meanwhile, a digital carrier regeneration (DCR) method is proposed to further reduce the optical carrier-to-signal power ratio of intensity modulated DMT signal based on silicon MZM, which will significantly increase the achievable system power budget, especially when a high-order modulation format is adopted. No carrier frequency offset and phase estimations are needed in the receiver, which greatly reduces the complexity for both laser and DSP in coherent detection. Finally, a 10-Gb/s/ch uplink transmission is experimentally demonstrated using the proposed DCR method over 20-km standard single-mode fiber (SSMF), achieving about -44dBm sensitivity under the 7% forward-error-correction (FEC) limit of bit error ratio (BER) = 3.8x10(-3).