We demonstrate a novel optical flip-flop configuration which consists of one Fabry-Perot laser diode
(FP-LD) and two Fiber-Bragg-Gratings (FBG).The all-optical flip-flop is realized based on the optical bistability of
injection-locked single-mode of FP-LD. The essential part to obtain bistability in this system is that the output of FP-LD
is fed back partly by two FBGs at certain wavelengths. The EDFA was used to adjust the power of feedback beam. The
on or off state of the All-optical flip-flop is determined by the set or reset light externally at different wavelength. The
all-optical flip-flop operated at the wavelength of 1537nm with on-off contrast ratio of 15 dB. The theory and
experimental result are presented.
A matrix theory which is capable of describing the Cross-polarization modulation (XPolM) in semiconductor optical
amplifier (SOA) is presented in this paper. Using the transfer matrix method, we prove that there exists Principal State of
Polarization (PSP) vector and Polarization Dependent Gain (PDG) vector in SOA. The evolution of output SOP on the
Poincare Sphere (PS) can be decomposed into two circles, which are induced by PDG and Polarization Dependent Phase
Shift (PDPS), respectively. The expressions of PSP vector and PDG vector with regard to inner parameters of SOA are
obtained. The pump-power induced evolution of output SOP is investigated experimentally. The experimental results
accord well with this matrix theory.