This Letter theoretically and experimentally studies the response of photonic switching in a channel-interleaved photonic analog-to-digital converter (PADC) with high sampling rate and wide input frequency range. A figure of merit (FoM) is introduced to evaluate the switching response of the PADC when a dual-output Mach–Zehnder modulator (MZM) serves as the photonic switch to parallelize the sampled pulse train into two channels. After the optimization of the FoM and utilization of the channel-mismatch compensation algorithm, the system bandwidth of PADC is expanded and the signal-to-distortion ratio is enhanced.

In recent years, the nanostructure for solar cells have attracted considerable attention from scientists as a result of a promising candidate for low cost devices. In this work, quantum dots sensitized solar cells with effective performance based on a co-sensitized CdS/CdSe:Mn2+ (or Cu2+) nanocrystal, which was made by successive ionic layer absorption and reaction, are discussed. The optical, physical, chemical, and photovoltaic properties of quantum dots sensitized solar cells were sensitized to Mn2+ and Cu2+ dopants. Therefore, the short current (JSC) of the quantum dot sensitized solar cells is boosted dramatically from 12.351mA/cm2 for pure CdSe nanoparticles to 18.990mA/cm2 for Mn2+ ions and 19.915mA/cm2 for Cu2+ ions. Actually, metal dopant extended the band gap of pure CdSe nanoparticles, reduced recombination, enhanced the efficiency of devices, and improved the charge transfer and collection. In addition, Mn2+ and Cu2+ dopants rose to the level of the conduction band of pure CdSe nanoparticles, which leads to the reduction of the charge recombination, enhances the light-harvesting efficiency, and improves the charge diffusion and collection. The results also were confirmed by the obtained experimental data of photoluminescence decay and electrochemical impedance spectroscopy.

This Letter demonstrates the effectiveness of a high-speed high-resolution photonic analog-to-digital converter (PADC) for wideband signal detection. The PADC system is seeded by a high-speed actively mode locked laser, and the sampling rate is multiplied via a time-wavelength interleaving scheme. According to the laboratory test, an X-band linear frequency modulation signal is detected and digitized by the PADC system. The channel mismatch effect in wideband signal detection is compensated via an algorithm based on a short-time Fourier transform. Consequently, the signal-to-distortion ratio (SDR) of the wideband signal detection is enhanced to the comparable SDR of the single-tone signal detection.

This Letter demonstrates the application of dual-output modulation in a photonic analog-to-digital converter (PADC) with a high sampling rate and resolution. The PADC is time-wavelength interleaved and based on an actively mode-locked laser. According to theoretical analysis, the dual-output PADC system shows a better linearity for achieving a higher dynamic range. In the experiment, third-order distortion is significantly suppressed by ～40 dB when the dual-output modulator is used and the effective number of bits of the PADC has reached 9.0 bits below 0.2 GHz and 6.4 bits at 6.1 GHz in our PADC with a sampling rate of 20 GS/s.

We present a compact, low-noise, and inexpensive optical phase-lock loop (OPLL) system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer technique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.

Parallel-coupled dual-racetrack silicon microresonators can potentially be used for quadrature amplitude modulation. We analyze the evolution of the coverage of coherent output states of devices with varying device parameters. As the coupling constant increases, the coverage of coherent states initially improves then degrades, which is unexpected based on a prior preference for overcoupling. Increasing the quality factor generally improves the coverage. The influence of the refractive index modulation is found to saturate after reaching a certain level. Analytic formulas are developed to provide insight into the coverage evolution. These results are fairly robust against a small asymmetry of device parameters.

We report all-optical regeneration of the state of polarization of a 40Gbit/s return-to-zero telecommunication signal. The device discussed here consists of a 6.2-km-long nonzero dispersion-shifted fiber, with low polarization mode dispersion, pumped from the output end by a backward propagating wave coming from either an external continuous source or a reflection of the signal. An initially scrambled signal acquires a degree of polarization close to 100% toward the polarization generator output. All-optical regeneration is confirmed by means of polarization and bit-error-rate measurements as well as real-time observation of the eye diagrams. We show that the physical mechanism underlying the observed four-wave-mixing-based polarization attraction phenomenon can be described in terms of the geometric approach developed for the study of Hamiltonian singularities.