Supercontinuum generation by higher-order mode excitation in a photonic crystal fiber.
We describe an experiment in which a train of femtosecond pulses is coupled into a photonic crystal fiber (PCF) by means of an offset pumping technique that can selectively excite either the mode LP(01) or LP(11) or LP(21). The PCF presents a wide range of wavelengths in which the fundamental mode experiences normal dispersion, whereas LP(11) and LP(21) propagate in the anomalous dispersion regime, generating a supercontinuum based on the soliton fission mechanism. We find that the existence of a cut-off wavelength for the higher-order modes makes the spectral broadening asymmetrical. This latter effect is particularly dramatic in the case of the LP(21) mode, in which, by using a pump wavelength slightly below cut-off, the spectral broadening occurs only on the blue side of the pump wavelength. Our experimental results are successfully compared to numerical solutions of the nonlinear Schrödinger equation.
Cirta'Com Laboratory, Engineering School of Communication of Tunis (Sup'Com), Ghazala Technopark, 2083, Ariana, Tunisia.
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D003198:Computer Simulation; D017076:Computer-Aided Design; D003460:Crystallization / Q000379:methods*; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008029:Lighting / Q000379:methods*; D008962:Models, Theoretical; D011789:Quantum Theory