Modified model for four-wave mixing-based wavelength conversion in silicon micro-ring resonators

A modified model for wavelength conversion based on the four-wave mixing (FWM) in a silicon micro-ring resonator is presented. Unlike previous contributions, the nonlinear phase shifts caused by self-phase modulation and cross-phase modulation are also taken into account in the present theoretical analysis besides the linear propagation loss and the nonlinear losses caused by two-photon absorption and free-carrier absorption. Analysis shows that the nonlinear phase shifts will cause different red shifts for the pump and signal (or converted) resonant wavelengths, and consequently an additional wavelength difference between the signal transmission dip and the efficiency peak, which will increase/decrease the conversion efficiency of the signal channel far from/near the pump. The conversion efficiency and the conversion peak width of each signal channel are both affected by the micro-ring radius and coupling coefficient. A broader conversion peak width can be obtained by using a micro-ring resonator with a smaller Q factor.     

基于相位调制和线性滤波的多信道多功能光学微分器

多功能微分器可以满足光计算和光信号处理中的多种需求, 增强灵活性. 本文从理论上推导了一种基于相位调制和线性滤波的多功能光学微分器. 并在实验中, 将传输谱线近似为线性的光纤延时干涉仪(DI)和相位调制器级联, 得到了输入信号的两种微分结果. 通过调节DI的驱动电压调节其传输谱的漂移, 当光载波位于DI的传输谱线的谷值, 则获得信号的光场微分, 当光载波位于DI传输谱的线性斜率处, 则得到输入信号的光强微分. 通过分析各种微分的平均误差, 发现DI的线性度越高, 平均误差越小. 同时基于DI传输谱线的梳状特性,证实了多信道信号的同时微分.     

激光干涉法测量硅高温环境下的线膨胀系数的实验研究

利用中国计量科学研究院自行设计的基于激光干涉法的材料线膨胀系数测量装置进行了材料线膨胀系数测量试验。该装置采用单频激光干涉，对称光路设计，其干涉仪分辨率小于1nm。实验过程中改进并完善了该装置，重新设计了加热炉，改进了实验方法，使该装置在800K以上的高温环境下能进行材料线膨胀系数的测量。在800K到1200K温度范围内，对单晶硅试样采用分段加热进行测量,并对样品变化过程及测量结果作了分析，得到了单晶硅线膨胀系数的曲线，实现了在1200K环境下采用激光干涉法材料线膨胀系数的纳米级测量。     

Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme

An all-optical analog-to-digital converter(ADC) based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift(SSFS) module within a wavelength range of 1550 nm–1580 nm. A dispersion coefficient as high as-19800 ps/(km·nm) with ±0.5 ps/(km·nm)variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate(MSSR) is 50.45 GSa/s with full width at half maximum(FWHM) variation less than 2.52 ps, along with the 2-bit effectivenumber-of-bit and Gray code output.     

Novel low‐loss waveguide delay lines using Vernier ring resonators for on‐chip multi‐λ microwave photonic signal processors

In this paper, novel photonic delay lines (DLs) using Vernier/non‐identical ring resonators (VRRs) are proposed and demonstrated, which are capable of simultaneous generation of multiple different delays at different wavelengths (frequencies). The simple device architectures and full reconfigurability allow the DLs to be integrated with other functional building blocks in photonic integrated circuits to realize on‐chip, complex multi‐λ microwave photonic signal processors with reduced system complexity. To prove the concept, DLs using VRRs in cascaded and coupled configurations have been fabricated in TriPleX^TM waveguide technology, which enables a very low delay‐induced loss of approximately 0.18 dB/100 ps. The fabricated DLs demonstrated simultaneous generation of four incremental delays, where a maximum incremental step of 550 ps and a corresponding top delay of 1650 ps were measured for a bandwidth up to 1 GHz. To our knowledge, this is the first report on VRRs for delay generation functionalities.     

Optical signal processing using four wave mixing in highly nonlinear silicon nano-wire

Silicon-on-insulator (SOI) waveguide devices are emerging for the realization of optical signal processing systems for the last couple of years. The recent technological advancement in silicon photonics is the main driving force at the back of these devices. Using non-linear optical phenomenon in silicon wires and their compatibility with CMOS devices provide the stage for integrated photonic devices. All-optical signal processing devices are being investigated at present, but the chip-scale solution provided by the silicon photonics is the most promising. In this research we have investigated all-optical signal processing in a 10 mm long SOI waveguide by exploiting well established coupled wave equations. We consider single pulsed pump to analyze frequency shifting by four-wave-mixing (FWM). For the wavelengths 20?30 nm far from the pump, the gain overcomes nonlinear losses resulting in higher frequency conversion efficiency.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.