Yuejiang Song

Investigation of the EDFA effect on the BER performance in space uplink optical communication under the atmospheric turbulence

In a ground-to-satellite communication system with a preset EDFA, the EDFAs performance will be affected by space environment. With 250 Gy radiation, the EDFAs gain decreases by 2 dB from 19.97 dB at 20 °C. The BER increases by 2.5 orders of magnitude from 10(-10), and increases more with more radiation. The situation aggravates when the temperature rises by 73 °C. The lasers divergence-angle and transmitter radius have optimal values to make the lowest BER and increasing receiver diameter makes lower BERs, so setting these parameters with appropriate values will compensate the degradation caused by EDFA.

Investigation of Black Box Model for Erbium-Doped Fiber Amplifiers in Space Radiation Environment

A black box model (BBM) of common environment is introduced to characterize the gain of erbium-doped fiber amplifier (EDFA) for any wavelength in the range of 1540-1560 nm in the radiation environment. Two erbium-doped fibers with different concentrations have been radiated to confirm the validity of the BBM. Using the method of BBM, the less measured parameters can overcome the restriction of the measured time in radiation environment. Therefore, that affords a new way to characterize the gain deterioration characteristic of EDFA in multiwavelength in radiation environment.

Dynamic Fano Resonance in Thin Fiber Taper Coupled Cylindrical Microcavity

Fano resonance results from interference between a background and a resonant scattering, which produces the asymmetrical lineshape. A cylindrical microcavity naturally possesses localized whispering gallery mode (WGM) and delocalized radiation mode, and a thin fiber taper can excite these two modes simultaneously. The localized WGM can interfere with the weak delocalized background to generate Fano resonance in the thin fiber taper coupled cylindrical microcavity. In addition, the Fano parameter can be adjusted by changing the gap between fiber taper and microcylinder cavity or the coupling diameter of fiber taper. The experimental results agree well with the quantum scattering theory.

Investigation of Costas Loop Synchronization Effect on BER Performance of Space Uplink Optical Communication System With BPSK Scheme

The Costas loop is the key technique of synchronous demodulation in the next generation of satellite optical communication systems. To better understand the Costas loop, the relationship between phase deviation of the Costas loop and bit error rate (BER) performance of a binary-phase-shift keying (BPSK) space uplink optical communication system is achieved. Furthermore, the BER performance versus frequency deviation, zenith angle, data rate, and divergence angle are analyzed. Simulation results indicate that BER performances are not sensitive for parameters when the phase deviation of the Costas loop is designed with restriction of

Multi-Channel Broadband Brillouin Slow Light With Multiple Longitudinal Mode Pump

\pi/16

Self-Adaptive High Anti-Radiation EDFA for Space Optical Communication Systems

. These results are helpful for enhancing BER performance and the design of space optical communication systems.

Time Division Multiplexing Optical Time Domain Reflectometry Based on Dual Frequency Probe

Independent delay control of multi-channel signals based on stimulated Brillouin scattering slow light is proposed and demonstrated for the first time by using a multiple longitudinal mode fiber laser. Two independent broadband Brillouin pumps are generated by a fiber ring laser, which use a semiconductor optical amplifier as gain medium. The spectrum of each pump is comprised of a large number of longitudinal lasing modes, separated by 7 MHz and spanning a bandwidth of 11.6 and 11.2 GHz, respectively. The multi-channel broadband Brillouin slow light is demonstrated by using 8 Gb/s data signals. The signals in both channels are continuously delayed by as much as 80 ps at 21 dBm pump power, and the maximal delay-time with error free operation (bit error rate <; 10-9) are up to 56.4 and 56 ps at 19 dBm pump power.

Effect of controllable parameter synchronization on the ensemble average bit error rate of space-to-ground downlink chaos laser communication system

In a space optical communication system with an amplification sub-system, the performance of the erbium-doped fiber amplifier (EDFA) will worsen due to the effect of space radiation. Consequently, the EDFA will not work under its optimal state which has been already designed on the ground. To fix this problem, a study on the basic characteristics of EDFA under radiation is conducted. In the simulation tests, the gain of EDFA and the optimal length of the erbium-doped fiber both decrease with the dose of radiation. To dynamically adapt to such effects, a new self-adaptive system is established and makes an improvement of 7 dB in the gain when the radiation dose reaches 5000 Gy. This paper can practically benefit the design of the space optical communication systems.

An Algorithm for Determining the Peak Frequency of BOTDR Under the Case of Transient Interference

A new frequency coding method is proposed and experimentally demonstrated that employs a phase modulator driven by sequential radio frequency and a synchronously controlled acoustooptic modulator to generate time division multiplexing probe pulses for coherent optical time domain reflectometry (C-OTDR). Each probe pulse contains two probe frequencies that are symmetrical regarding the frequency of local oscillator (LO). Heterodyne between the backscattered Rayleigh light of the dual frequency probe pulse and LO generates the same intermediate frequency. Experimental results show that the new C-OTDR, using ten frequency-coded probe pulses, brings an 8.0-dB dynamic range enhancement, compared with conventional C-OTDR.

Investigation on the influence of intensity scintillation and beam wander in space optical uplink DWDM communication system

Chaotic modulation is a scheme used to enhance the information security through the configuration parameter synchronization. When chaotic modulation is adopted in the space-to-ground laser communication system, the traditional bit error rate (BER) calculation model for fiber-based chaos communication system is no longer available to depict the long-term communication performance. To solve this problem, we established a new ensemble average BER calculation model under the effects of intensity scintillation and pointing error. Based on this model, we conduct a simulation to research such a system, and our numerical results indicate that space-to-ground chaos laser communication system has a great anti-interference against these two effects when the detector mismatch approaches zero. Our results display the advantages of chaotic modulation and also reflect the characteristics of space-to-ground chaos laser communication system.