Xinzhi Sheng

Combination of Phase-Sensitive OTDR and Michelson Interferometer for Nuisance Alarm Rate Reducing and Event Identification

In order to obtain low nuisance alarm rate (NAR) and achieve the disturbance event identification, the wavelength-division multiplexing combination of a phasesensitive optical time-domain reflectometer (φ-OTDR) and a Michelson interferometer (MI) is proposed and demonstrated. The disturbance is synchronously detected by a φOTDR and an MI. A true alarm is presented only when a real disturbance is detected by both φ-OTDR and MI. Furthermore, the event identification of the confirmed real disturbance is recognized by an equivalent frequency distribution analysis on the MI signal. It is found that, by the experiment, NAR can be reduced to 1.2% from 13.5% via a single φ-OTDR, with a high detection probability of 92%. Furthermore, four disturbance events can be distinguished with a 90% identification rate. Our proposed wavelength-division multiplexing of a φ-OTDR and an MI is simple and low cost, no complicated algorithm is required, and only one sensing fiber is needed; therefore, it is an interesting exploration of multiplexing of φ-OTDR and interferometers.

Demonstration of low-loss flexible fiber with Zeonex tube-lattice cladding for Terahertz transmission

A Zeonex hollow-core terahertz fiber was developed successfully. The lowest loss is 1dB/m at the frequency below 1THz, which is much lower than THz fibers reported. The loss is still below 5dB/m when its bent.

Broad-Band All-Optical Wavelength Conversion of Differential Phase-Shift Keyed Signal Using an SOA-Based Nonlinear Polarization Switch

Broad-band all-optical wavelength conversion of differential phase-shift keyed (DPSK) signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a semiconductor optical amplifier (SOA) based nonlinear polarization switch. A wavelength converter for the 10 Gb/s DPSK signal is presented, which has a wide wavelength range of more than 30 nm. The converted signals experience small power penalties less than 1.4 dB compared with the original signal, at a bit error rate of 10−9. Additionally, the optical spectra, the measured waveforms and the open eye diagrams of the converted signals show a high quality wavelength conversion performance.

Surface Brillouin scattering in transverse anderson localization disordered optical fibers

We have investigated the surface Brillouin scattering (SBS) in the transverse Anderson localization (TAL) disordered optical fibers (DOFs), theoretically and numerically. There are random air-holes in the across of silica DOF, and the disordered silica glass-air structure can bring in TAL to the light, as a result, an optical fiber can be produced. The SBS in this TAL DOF is then numerically investigated. It is found that there are two main peaks in the SBS spectrum, and the Brillouin frequency shift is sensitive to the air fill-fraction of the TAL DOF. It seems to be that this result can be utilized in the longitudinal structural fluctuations monitoring of TAL DOF.

All-optical regenerative wavelength multicasting for differential phase shift keyed signal based on a single semiconductor optical amplifier

Abstract. An all-optical regenerative wavelength multicasting scenario for differential phase shift keyed (DPSK) signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a single semiconductor optical amplifier. The experimental results show that the input signal wavelength is simultaneously converted to six different wavelengths at 10  Gb/s with signal regeneration. The power penalties, for all different wavelengths, are less than −0.8  dB at 10−9  bit error rate (BER) level.

Experimental investigation of all-optical nonreturn-to-zero differential phase-shift keying to return-to-zero DPSK format conversion based on nonlinear polarization rotation of semiconductor optical amplifier

A novel all-optical nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) to return-to-zero DPSK (RZ-DPSK) format conversion scheme is proposed and experimentally demonstrated. This conversion is based on nonlinear polarization rotation of a semiconductor optical amplifier. Experimental results show that a 10 Gb/s RZ-DPSK signal with an extinction ratio over 10 dB can be converted with a tunable duty cycle from 33% to 66%, and the ER of the converted signal decreases with the increase in the duty cycle. For all cases of different duty cycles, the converted signals experience a -0.4 to -1.2  dB power penalty at a bit error rate of 10(-9) compared with the original signal. In addition, the spectra show that this format conversion is a wavelength-preserved operation.

Investigation on the influences of fiber link and laser source on performances of RoF transmission with WiMAX for 16 QAM

In this paper, the influences of fiber link and laser source on performances of Radio over Fiber (RoF) including error vector magnitude (EVM), constellation and eye diagram are investigated by simulation using Opti-system12 (trial version). The investigated RoF network is built on IEEE 802.16a WiMAX, with 16 QAM and a Mach-Zehnder modulator for intensity modulation. The mechanism of that the dispersion in fiber link makes the constellation rotate is investigated. The relationship between the rotation angle of the constellation and dispersion is analyzed, where we first put forward a fitting formula to describe this approximate quantitative relation. In the analysis of the influence of the laser source on the network, where the dispersion compensates fiber (DCF) is applied to compensate the rotation in constellation caused by fiber link, the threshold in the relationship curve of the linewidth and EVM is obtained. It is found that if the laser linewidth exceeds this threshold, the EVM will increase rapidly, then, the performance decreases.