Chun Tian

Rapidly reconfigurable optical phase encoder-decoders based on fiber Bragg gratings

We demonstrate the capacity for fast dynamic reconfiguration of optical code-division multiple access (OCDMA) phase en/decoders based on fiber Bragg gratings and a thermal phase-tuning technique. The tuning time between two different phase codes is measured to be less than 2 s. An OCDMA system using tunable-phase decoders is compared with a system using fixed-phase decoders and, although the system using fixed-phase decoders exhibits a shorter output autocorrelation pulsewidth and lower sidelobes, the system using tunable-phase decoders has advantages of flexibility and a more relaxed requirement on the input pulsewidth

Direct characterization of the spatial effective refractive index profile in Bragg gratings

We propose a pulse response method to directly characterize the phase of the spatial index modulation, including the dc refractive index distribution (distributed phase shift), discrete phase, and chirp of fiber Bragg gratings (FBGs). This method is based on the observation that the spatial phase of gratings is directly related to the temporal phase of its pulse response. Therefore, the phase of the spatial index modulation can be characterized directly by measuring the temporal phase of the pulse response of FBGs. This method is then used to characterize an FBG with a current-induced phase shift.

A 16-Channel Reconfigurable OCDMA/DWDM System Using Continuous Phase-Shift SSFBGs

We demonstrate a reconfigurable 16-channel optical code-division multiple access (OCDMA)/dense wavelength division multiplexing (DWDM) system (4 OCDMA times 4 DWDM times 625 Mb/s) based on novel 31-chip, 40 Gchip/s quaternary phase coding gratings operating at a channel spacing of just 50 GHz. The system performance is studied for cases of both fixed and code-reconfigurable decoders. Error-free performance is achieved in both cases and for all 16 channels.

Demonstration of a 16-channel code-reconfigurable OCDMA/DWDM system

We report a reconfigurable 16-channel OCDMA/DWDM system (40CDMAx4DWDMx625Mbit/s) based on novel 31-chip, 40 Gchip/s quaternary phase coding gratings operating at a channel spacing of just 50GHz. Error free performance is achieved for all channels.

Reduction of Multiple Access Interference in a DS-OCDMA System via Two-Photon Absorption

We demonstrate a technique to suppress multi-access interference in an OCDMA system by using the nonlinear process of two-photon absorption. This allows the extinction ratio to be improved by 5 dB when compared to linear detection.

Reconfigurable all-optical packet switching based on fiber Bragg gratings

We report an all-optical bit-serial packet switched system which uses a fiber Bragg grating (FBG)-based reconfigurable device to recognize optical headers. The decoder is compatible with fixed SSFBG header encoders and has a reconfiguration time of < 2 s

A Reconfigurable Optical Header Recognition System for Optical Packet Routing Applications

We demonstrate a reconfigurable all-optical packet processing system. The key device is a code-reconfigurable header decoder based on a fiber Bragg grating. The performance of the system is tested for different packet headers, and error-free operation is confirmed

Distributed-Phase OCDMA Encoder–Decoders Based on Fiber Bragg Gratings

We propose and demonstrate new optical code-division multiple-access (OCDMA) encoder-decoders having a continuous phase-distribution. With the same spatial refractive index distribution as the reconfigurable optical phase encoder-decoders, they are inherently suitable for the application in reconfigurable OCDMA systems. Furthermore, compared with conventional discrete-phase devices, they also have additional advantages of being more tolerant to input pulsewidth and, therefore, have the potential of bandwidth saving

Fibre Bragg Grating Based Continuous-Phase Encoder-Decoders for OCDMA Networks

Continuous-phase OCDMA encoder-decoders are proposed and demonstrated. Compared with conventional discrete-phase devices, they have additional advantages of being more tolerant to input pulse-width and furthermore will facilitate the use of reconfigurable phase-codes.

Rapidly reconfigurable phase code generation and recognition using fiber Bragg gratings

We demonstrate a 16-chip, 40 Gchip/s, reconfigurable fiber Bragg grating based quaternary phase en/decoder with a tuning time of <2s between two different phase codes