Nonlinear filtering by use of intensity-dependent polarization rotation in birefringent fibers

Abstract

We analyze the transmissivity of a nonlinear filter that is based on intensity-dependent polarization rotation in a birefringent fiber. It is shown that the transmissivity of the element depends not only on the intensity of the incident light but also on the time behavior of its amplitude. Such an element can be used as a derivator, an element that transmits only variations in the input pulse. The filter can also be used for obtaining lasers that generate a train of intense noiselike pulses with a broadband spectrum and a short coherence length.

Mechanism of intrinsic wavelength tuning and sideband asymmetry in a passively mode-locked soliton fiber ring laser

“…It has been pointed out by Horowitz et al that the birefringence in the laser cavity can be very significant owing to the winding of fibers and the nonuniformities of the EDFA in the laser cavity. 6,7 This birefringence value gives a good qualitative agreement between the experimental and the simulation results. Finally, the projection of light onto the analyzer is described by …”

“…This is an analogy for how the group delay owing to birefringence prevents the short-pulse formation in the laser. 6,7 Therefore to obtain a shorter pulse, which means larger bandwidth, a smaller birefringence in the laser cavity is required. Owing to the dispersive nature of the system, the central wavelength of the mode-locked pulse is not determined solely by the spectral gain profile of the EFDA.…”

“…Novel features such as the transform-limited soliton-pulse formation, 1,2 pulse-energy quantization, 2,3 harmonic mode locking, 4,5 and noiselike-pulse output 6,7 have been observed in the laser. In this paper we report on another intrinsic behavior of the laser; we show experimentally that by simple adjustment of the polarization controllers of the laser, the central wavelength of the mode-locked pulses can be continuously tuned.…”

Modulation instability induced by periodic power variation in soliton fiber ring lasers

“…Although in a fiber ring laser the dispersive waves periodically experience gain provided by the erbium-doped fiber and loss at the output coupler which lead to periodic power fluctuation, this kind of power variation is too small and the modulation instability with subsideband generation can not be observed in the experiment [15]. Nevertheless, when the strength of dispersive waves is strong enough, a larger periodic power variation of dispersive waves induced by the interaction between intensity-dependent polarization rotation and passive polarizer [16][17][18][19] can be realized by properly setting the linear cavity phase delay. In this paper, we present the experimental observation of modulation instability induced by periodic power variation in a passively mode-locked fiber ring laser.…”

Electrically and optically controlled cross-polarized wave conversion

“…Utilizing the nonlinear polarization rotation has been intensively studied for pulse reshaping [12]- [13], light modulation [14], intensity discrimination [15]- [16], optical logic gating [12], and mode locking in fiber lasers [17]- [18]. Although the analysis during this paper is carried out for isotropic media, which we consider to have applicability advantages, the same approach is workable for birefringent crystals whereby the external field may either enhance the desired effect or act as an adaptive control.…”