Fu Songnian

Relative phase noise induced impairment in CO-OFDM optical communication system with distributed fiber Raman amplifier

In this Letter, we demonstrate that the interplay between Raman pump relative intensity noise and cross-phase modulation leads to a relative phase noise (RPN) that brings non-negligible performance degradation to coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission systems with co-pumped Raman amplification. By theoretical analysis and numerical simulation, we proved that RPN brings more system impairment in terms of Q-factor penalty than the single carrier system, and relatively larger walk-off between pump and signal helps to suppress the RPN induced impairment. A higher-order modulated signal is less tolerant to RPN than a lower-order signal. With the same spectral efficiency, the quadrature-amplitude modulation format shows better tolerance to RPN than phase-shift keying. The reported findings will be useful for the design and optimization of Raman amplified CO-OFDM multi-carrier transmission systems.

Pump RIN Induced Impairment in Raman Amplified Coherent Optical Communication System using 16-QAM

Pump RIN induced relative intensity noise and relative phase noise in Raman amplified coherent optical communication system using 16-QAM modulation format are analyzed. 0.1 dB Q-penalty will be caused by -120 dB/Hz pump RIN.

Electrically wavelength tunable active mode-locked fiber laser using a phase modulator as both mode locker and wavelength selector

We experimentally demonstrate a 10 GHz electrically wavelength tunable active mode-locked fiber laser with a phase modulator serving as both mode locker and wavelength selector. Tuning of 4 nm with 1.2 V bias voltage is obtained.

Calculation of geometrical birefringence from two-dimensional refractive-index profile in single-mode fibres

We present two numerical approaches to calculate the geometrical birefringence from two-dimensional refractive-index profile in single-mode fibres. One is the improved perturbation model theory, the other is based on the general solution of noncircular uniform optical waveguide in an arbitrary coordinate system. Using these methods, we can obtain not only the magnitude of geometrical birefringence, but also the orientation of birefringent axes. We report the calculation results of geometrical birefringence in a real single-mode fibre.

Multiplexed polarization-OTDR system for multi-event detection

A novel scheme of polarization optical time domain reflectometry (POTDR) with a high degree of polarization was proposed for multi-event detection. Multiple 2×2 optical fiber couplers and fiber mirrors were employed for the multiplexed POTDR system. The system can be used for multi-event detection while the signals signal-to-noise ratio be improved significantly and the temporal depolarization effect can be almost completely suppressed. Without performing any data averaging, the intrusion event (action of removing fiber) can be detected and located precisely/instantaneously with good stability. Also the frequency components of vibration events can be obtained with a large dynamic range. In this paper intrusion behavior with low frequency and up to 950Hz vibration frequency has been detected simultaneously while the pulse repetition frequency is 2KHz. It shows a very good potential in intrusion detection, vibration frequency measurement, etc.

A Strain Insensitive Temperature Sensor Based on In-fiber Integrated Multipath Interferometer

We proposed and experimentally demonstrated an in-fiber integrated multipath interferometer using all-solid multi-core fiber for temperature sensing applications. A high temperature sensitivity of 130.6pm/centigrade and a record low strain-to-temperature cross sensitivity of 1.95×10-3 centigrade/μϵ were achieved.

Simultaneous both inter-symbol and inter-channel interference mitigation for Sub-Nyquist WDM Superchannel Systems

A filtering bandwidth insensitive joint signal processing is proposed for sub-Nyquist superchannel. Both ICI and ISI cancellation are achieved over a wide range of filter bandwidth for 50GHz-spaced 56 GBaud PM-QPSK superchannel

Design and Optimization of Multi-core Fibers with Low Crosstalk and Large Effective Area

We performed intensive simulation work to find out key parameters which have a great influence on crosstalk in multi-core fibers. The design of core pitch, core/trench profile were optimized simultaneously.

Investigation on the Wavelength Dependent Crosstalk of Multicore Fibers

We investigate the wavelength dependent crosstalk of MCF. After fabrication and characterization, we find that the crosstalk increases with the operation wavelength at rate of 0.1dB/nm for both homogeneous MCF and quasi-homogeneous MCF.