Taorong Gong

Clock Recovery and Demultiplexing for 80Gbit/S OTDM System

Demultiplexing for OTDM networks utilizing a pair of concatenated electroabsorption modulators (EAMs) is presented and demonstrated experimentally. 80Gbit/s OTDM signal is demultiplexed to base rates of 20 and 10Gbit/s with the two EAMs, respectively. The two EAMs combined with a 10GHz clock recovery module based on phase-locked loop is introduced to extract the frame clock from 80Gbit/s OTDM signal. Keywords-optical time division multiplexing (OTDM); demultiplexing;clock recovery (CR), electrical absorption modulator(EAM).

Analysis of Transmission Characteristics of PFBG Based on FEM with 1st-order transparent boundary conditions

The transmission characteristics of a nonuniform photonic fiber Bragg grating (PFBG) are studied in detail by FEM furnished with 1st - order BGT - like TBC and transfer matrix method. The effects of the air hole size on PFBGs transmission properties such as effective index, Bragg reflective wavelength, normalized bandwidth and centre wavelength shift are investigated. It is believed the study can provide useful information for PFBGs design and optimization with a more effective and accurate method.

Comparison of the properties among photonic crystal fibers with different elliptical inner cladding configuration

Some kinds of high birefringence photonic crystal fibers (PCFs) with elliptical inner cladding are analyzed by Galerkin finite element method with transparent boundary conditions (TBC). Several properties of them, such as the birefringence, confinement loss and dispersion are deduced and compared .It is shown that PCFs with different elliptical inner cladding formed by enlarging or diminishing air holes have different properties. High birefringence can be obtained through intruding the difference of air holes size along orthogonal direction. Enlarged air holes reduce the CL, and increase the dispersion and dispersion slope; but diminished air holes is reversed.

Optimization of Wide-Band Flat-Gain Telluride-Based Fiber Raman Amplifier

A multi-pumping scheme to get a gain-flattened fiber Raman amplifier is presented and a complete computing model is established to optimize the pump wavelength and power allocation with flat gain and broad bandwidth.

Impact of apodisation functions on group delay and reflectivity ripple of chirped fiber Bragg gratings

Apodisation technology is introduced to optimize fiber Bragg grating based on the analysis of reflectivity spectrum and group delay response of fiber Bragg gratings. The characteristics of Hamming, Gauss and super-Gauss functions are discussed and the optimization effects of the three apodisation functions on ripple smoothness of reflectivity spectrum, group delay and linear degree are compared respectively. As a result, the optimization effects of Hamming function is better than other two functions. When the bandwidth is less than 1dB, Super-Gauss function is the best choice and proper parameters (G and m) of super-Gauss function can be selected expediently for wider bandwidth and better ripple smoothness of reflectivity spectrum.

160 Gb/s OTDM demultiplexing based on two cascaded electro-absorption sampling windows

One 160 Gb/s optical time division demultiplexer based on two cascaded electro-absorption modulators as sampling windows was demonstrated and experimentally studied in detail. The two stages were used for the 160 Gb/s into 40 Gb/s demultiplexing and 40 Gb/s into 10 Gb/s demultiplexing respectively.

Study on the polarization scrambling time for ultra-high-speed optical fiber communication systems

A 160Gbit/s optical time-division-multiplexing (OTDM) transmission system with polarization Scrambler is demonstrated experimentally. The Scrambler based on the structure of the all-fiber dynamic polarization controller (PolaRITE II by General Photonics Co.). The polarization controller is controlled accurately the peak scrambling frequencies and the corresponding half-wave voltages by home-made a singlechip circuit. Both theory and experience show that the rate of scrambler is related to the spectrum width, spectral distribution, modulation rate and so on. The rate of Scramble for broadband light would be much slower compare with narrowband light to carrying out depolarization. In the same width of spectrum, light with abundant spectrum would need a slower rate. The relationship between the Rate of Scrambler and the Character of different Lasers will be discussed by using Stokes parameters and Mueller matrix. And the experiments performed to verify the results of theoretical analysis results. The Scrambler can reduce Intersymbol Interference, Polarization Mode Dispersion (PMD) and Polarization Dependent Loss (PDL) that have are validated experimentally. Based on the Scrambler, the 160-Gb/s OTDM transmissions are successfully demonstrated.

Study on the performance of the stress area mismatched Panda erbium-doped polarization-maintaining fiber

Influence of stress area mismatched Panda erbium-doped polarization-maintaining fibre on the birefringence is analyzed and compared by finite element method and approximate analytical expression educed by the complex variable method of elasticity with superposition techniques.

Design and experiments on multiwavelength fiber lasers

A simple multi-wavelength erbium-doped fiber laser with narrow-line-width lasing output was proposed and demonstrated using fiber Bragg gratings and Arrayed-Waveguide Gratings (AWG). Wavelength competition was naturally prevented in this kind of laser by using AWG in the linear-cavity. As an example, a triple-wavelength erbium-doped fiber laser was experimentally investigated. Using the laser scheme, the proposed laser can laser three wavelengths simultaneously. The fiber laser retrieved the optical side-mode suppression ratio of over 50dB and the average output power of -10.714, -10.649 and -10.578dBm at 1554.710, 1555.516 and 1556.421nm, respectively. And the 3-dB bandwidth of each laser was less than 0.010nm. Moreover, the output power stability of the laser had also been measured and analyzed. Experiment results showed that the laser can be operated stably in narrow-line-width with single- and triple-wavelength output at room temperature.

Fabrication of photosensitive polarization-maintaining erbium-doped fiber and application for fiber laser

A new method of fabricating Panda-type photosensitive polarization-maintaining erbium-doped fiber(PM-EDF) is proposed and demonstrated. A sample of PM-EDF is fabricated using this method and an exhaustive analysis is made about the characteristics of PM-EDF, the results shows that this method is practicable. Two fiber Bragg Gratings (FBGs) are written into PM-EDF directly as the lasers reflectors, a three-states-tuned fiber laser is then obtained using a polarization controller (PC).