A study of fiber optic CDMA systems and optical signal processing

In this thesis, we introduced the fiber Bragg grating (FBG) as the en/decoder in fiber optic code division multiple access (FO-CDMA) systems and studied the incoherent 2-dimensional (2-D) FO-CDMA scheme using the FBG en/decoder.; The incoherent 2-D coding operation with the FBG en/decoder has been demonstrated experimentally for the first time. The coding operations are realized successfully with bit rates up to 1Gbit/s. The system performance is also evaluated in different cases.; We introduced the free-running gain-switched F-P laser for this application. The influence of the mode partition noise (NTN) in the F-P laser in the system is studied theoretically and the experimentally. Transmission at 1 Gbits/s with this source was demonstrated, the experimental result agrees well with the theoretical prediction.; A novel laser scheme by using the self-seeded gain-switched F-P laser with sub-harmonic pulse-gating in an external cavity consisting of a FBG encoder is for the first time proposed and demonstrated experimentally. In the experiment, four-wavelength optical pulse trains with several different 2-D code patterns have been generated sequentially at a repetition rate 250MHz. The output pulses obtained by this method are much more intense and stable, and it has the potential to allow switching between different 2-D codes by reconfiguring the FBG encoder. Error free transmission over 10km SMIF has been demonstrated with this source at 250Mbit/s bit rate.; The influence of the phase induced intensity noise PIIN in the fiber optic recirculating delay line (FORDL) notch filter is studied theoretically and experimentally. Three methods are proposed to reduce the PIIN in this situation. An optimal notch filter is achieved using these methods.; Finally, we proposed and demonstrated a novel all-optical incoherent bipolar tapping technique. It exploits the cross intensity modulation of the longitudinal modes due to the carrier depletion effect of an injection-locked F-P laser diode to perform negative tapping. A delay line canceller (DLC) is realized by this scheme with a canceling ratio of about 30dB. A novel tunable all-optical bipolar delay line filter scheme has also been proposed and demonstrated experimentally. The recursive and non-recursive filtering functions are realized by simply tuning the FBGs.