Xiangqing Tian

All-Optical Format Conversion From NRZ to BPSK Using a Single Saturated SOA

All-optical format conversion from nonreturn-to-zero (NRZ) to binary phase-shift keying format is experimentally demonstrated at 8 Gb/s using a single semiconductor optical amplifier (SOA). The conversion is based on the gain and phase modulations of the SOA on an input NRZ signal of finite extinction ratio

Optical VPN in PON Based on DPSK Erasing/Rewriting and DPSK/IM formatting using a Single Mach-Zehnder Modulator

We demonstrate a novel PON scheme enabling optical VPN functionality using DPSK/IM format. DPSK is used for downstream and upstream traffic, while IM is superimposed on the DPSK signal for VPN traffic.

Optical VPN Connecting ONUs in Different PONs

We demonstrate optical-layer virtual private networking in a new super-PON architecture using a dynamic wavelength reflector. The optical VPN enables communications among different PONs.

Optical VPN in PON Using TDM-FDM signal format

We demonstrate a simple and low-cost PON with optical VPN functionality using a directly modulated laser diode to generate TDM-FDM format. This format enables that one tributary of the transmitted signal be reflected to ONUs in the same optical VPN.

Precise in-band OSNR and spectrum monitoring using high-resolution swept coherent detection

We propose and demonstrate a novel in-band optical signal-to-noise-ratio (OSNR) and spectrum monitoring technique based on swept coherent detection. This technique measures the signal and the in-band amplified spontaneous emission spectra by properly adjusting the polarization states of the signal and the local oscillator. A high resolution of 0.002 nm is achieved. By integrating the detected spectra of the signal and the noise, the in-band OSNR can be obtained in a very precise manner. We monitor the OSNR values with high accuracy in the range of 10-30 dB.

Nonlinearity-tolerant in-band OSNR monitoring for synchronous traffic using gated-signal RF spectral analysis

We demonstrate a new in-band OSNR monitoring scheme using RF spectral analysis of gated framing-signal of synchronous traffic. The proposed technique is simple and robust to fiber-nonlinearity induced polarization rotation in WDM systems

Performance Study of 40-Gb/s RZ Signals Through Cascaded Thin-Film Filters with Large Dispersion Slope.

The performance of 40-Gb/s RZ signals through cascaded thinfilm filters is investigated by both numerical and analytical means. It is observed that the filtering effects can reduce the eye closure penalties caused by the large dispersion slope of the thin-film filters. In addition, the performance can be further improved by proper frequency detuning between the signal and the center of the filter. The combined effects of dispersion slope and filtering on 40-Gb/s signals are investigated analytically and explained for typical bit patterns.

Two novel multigranularity optical cross-connect architectures for hierarchical optical networks

Two novel multi-granularity optical cross-connect (MG-OXC) architectures for dense wavelength division multiplexing (DWDM) networks are proposed to realize transparent waveband switching, and hence to reduce the switching and transmission costs. The performances of the two architectures are studied and compared in detail. The functionality of the proposed interconnecting architecture is investigated for a 10-Gb/s WDM system.

Optical Fiber Polarization Interferometer for Performance Improvement in Radio-Over-Fiber Systems

An extinction ratio tunable optical fiber polarization interferometer (OFPI) is proposed and implemented to increase the optical modulation depth in radio-over-fiber (RoF) systems by suppressing the optical carrier power. The extinction ratio of the OFPI can be simply tuned by adjusting the polarization state of the launched RoF signal. Experimental results illustrate that the receiver sensitivity and dynamic range of RoF systems are greatly improved using the proposed scheme.

A Multi-Format Transmitter Using a Single Dual-Parallel Mach-Zehnder Modulator

We propose a novel scheme for generating duobinary, RZ-AMI and Manchester formats using a dual-parallel Mach-Zehnder modulator at 10 Gb/s. The performance of the generated signals is investigated for back-to-back operation and after transmission.