Optical Sensor Using Space-Domain Active Fiber Cavity Ringdown Technique

A novel active fiber cavity ringdown (FCRD) technique using frequency-shifted interferometry (FSI) is proposed for the first time. Using this scheme, external parameters can be monitored in the space domain by measuring the ringdown distance instead of ringdown time. A bidirectional erbium-doped fiber amplifier (Bi-EDFA) is employed to compensate the inherent cavity loss for achieving higher sensitivity. And two band-pass filters are used to reduce the amplified spontaneous emission (ASE) noise of the Bi-EDFA. Compared with the well-known time-domain active FCRD scheme, our proposed method enables us to avoid using pulsed laser needed in time-domain active FCRD, it uses continuous-wave laser to inject into the fiber cavity and stabilize the optical power in the fiber cavity, which can suppress gain fluctuations of the EDFA and thus improve the detecting precision. Moreover, this novel method enables us to use differential detection method for further reducing the ASE noise, and thus eliminating the baseline drift of ringdown signal. A magnetic field sensor was developed as a proof-of-concept demonstration. The experimental results demonstrate that the proposed sensor with a sensitivity of 0.01537 (1/km·Gs) was achieved. This is the highest magnetic field sensitivity compared to the time-domain active FLRD method. Due to the reduced ASE noise, the stability of the proposed sensing system was also greatly improved.

Performance analysis of APD and PIN diode with and without EDFA in GPON

Gigabit-capable passive optical network (GPON) is a passive optical network that provides faster data transmission and reception using point-to-multipoint access technology with single fiber. Using passive splitter in distribution network to keep the costs down, its 2.5 Gbits/sec bandwidth can be split up to 64 times. This paper presents the study of max Q-factor, min bit error rate (BER) using Opti system 17. In this study return to zero (RZ) and nonreturn to zero (NRZ) line codes analyzed by using P-insulator-N (PIN) and avalanche photo diode (APD) receivers. This paper also studies the impact of CW laser power on Q factor and min BER of GPON with and without erbium-doped fiber amplifier (EDFA).

Bidirectional High-speed Chaotic Communication System based on an All-optical Time-delay Feedback Loop

In this paper, a bidirectional high-speed chaotic optical communication scheme with physical layer encryption is proposed and studied theoretically. The external cavity optical feedback method is analyzed, an erbium-doped fiber amplifier (EDFA) is used to represent the all-optical delay feedback loop of the traditional external cavity, which can overcome the shortcomings of the traditional method such as lower precision and large equipment volume. And the bidirectional communication scheme is discussed, which just sets the encryption device at the transmitter, uses the correlation between the two encryption signals to decrypt, and cancels the decryption device at the receiver, which not only simplifies the experimental equipment, but also solves the problem that the receiver can’t decrypt synchronously due to the channel damage in remote communication, and is easy to be applied in production and life. Finally, the simulation results show that the bit error rate is less than 10− 5, the bidirectional transmission of 10Gb/s information over 85km single-mode fiber is successfully realized.

CWDM communication system based inline erbium-doped fiber amplifiers with the linear geometrical polarization model

Optical fiber coarse wavelength division multiplexing (CWDM) with erbium-doped fiber inline-amplifiers for the linear polarization geometrical model is studied in this paper for fiber system optimization by using the Optisystem simulation software. Signal gain (SG), noise figure (NF), and signal/noise are measured against CWDM optical fiber variations. The erbium-doped fiber amplifier (EDFA) is based on the Giles model which solves the steady-state rate equations for SG and signal absorption parameters with the cross-section area of the amplifier itself. The signal is optimized at EDFA length of 6 m, 10 Gb/s data rates (DRs) transmission and 10 km CWDM fiber optic length (FOL). Max. Q factor is degraded and min. BER is upgraded with both CWDM optical FLs and higher DRs transmission increase.

Nonlinear/dispersion compensation in dual polarization 128-QAM system incorporating optical backpropagation

In order to cater long distance optical network units (subscribers), optical networks with prolonged reach are needed. In this study, an optical back propagation (OBP) dual polarization (DP)-128 QAM-based system is proposed to cope with nonlinear impairments in wavelength division multiplexing (WDM) systems. In pre, post and symmetrical configurations, the OBP module consisting of the optical phase conjugator (OPC), Raman fiber amplifier (RFA) and erbium doped fiber amplifier (EDFAs) is examined. Using dispersion compensation fiber (DCF) as RFA with dual directional pumping, ideal OBP conditions are simulated. DP-128 quadrature amplitude modulation (QAM) system is proposed with symmetrical OBP and compared with single channel digital back propagation (DBP), wideband DBP, pre OBP-forward pumping, pre OBP with backward pumping, pre OBP with dual directional pumping, post OBP with dual directional pumping. It is observed that symmetrical OBP configuration with dual direction pumping provide enhanced results and successfully cover 6500 km at bit error rate (BER) 10−3.