Theory of nonlinear loop mirrors with twisted low-birefringence fiber

Effect of control-beam polarization and power on optical time-domain demultiplexing in a new nonlinear optical loop mirror design

“…21,22 Our approximation neglects the fiber dispersion and is valid when the pulse widths are sufficiently long to yield a dispersion length longer than the fiber length. 16 The next differential equations describe the polarization states of beams propagating in a birefringent twisted fiber along the z axis in the circular polarization basis:…”

“…͑1͒ and ͑2͒, into the often used eigenmode polarization basis. 16 We transform complex amplitudes C + and C − into polarization eigenmodes S + and S − .…”

“…The data and control signals must be thoroughly synchronized so that no additional phase shift caused by data signal time jitter occurs. 15 The control-beam-driven switching in a conventional NOLM is based on the cross-phase modulation ͑XPM͒ 2,3 or the self-phase modulation ͑SPM͒ [16][17][18] in both polarizationmaintaining and nonpolarization-maintaining fibers. The key point of the scheme proposed by Kuzin et al [16][17][18] relies on the nonlinear polarization rotation thanks to the use of a twisted nonlinear fiber and a quarter-wave plate inserted in the loop.…”

“…[16][17][18] We analyze a control-beam-driven NOLM using a symmetrical data input coupler in which the switching properties are achieved by control-beam power and the management of the nonlinear polarization rotation between data and control beams only. The transmissions of the NOLM scheme without a quarter-wave plate are simulated based on the theoretical model presented in the Sec.…”

Large amplitude noise reduction in ultrashort pulse trains using a power-symmetric nonlinear optical loop mirror

“…Still, fibre birefringence and polarisation evolution modify the NOLM operation, and a few groups tried to figure out how it happens. Some of the first studies of polarisation effects in NOLMs can be found in [19,20], but a comprehensive study of polarisation effects in NOLMs [21] would follow by more than a decade the funding paper by Doran et al [1]. In [22], the first thorough study of the impairments imposed by residual birefringence on the NOLM operation was presented.…”