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- All-optical switching (3)
- Asymmetric coupler (2)
- Coupled generalized nonlinear Schrödinger equation (2)
- Dual-core photonic crystal fiber (2)
- Nonlinear directional coupler (2)
- Soft glass (2)
- Ultrafast soliton fission (2)
- Dispersion tailoring of optical fibres (1)
- Dual-core fibre (1)
- Dual-core optical fibres (1)
Organisationseinheit der BAM
We demonstrate ultrafast soliton-based nonlinear balancing of dual-core asymmetry in highly nonlinear photonic crystal fiber at sub-nanojoule pulse energy level. The effect of fiber asymmetry was studied experimentally by selective excitation and monitoring of individual fiber cores at different wavelengths between 1500 nm and 1800 nm. Higher energy transfer rate to non-excited core was observed in the case of fast core excitation due to nonlinear asymmetry balancing of temporal solitons, which was confirmed by the dedicated numerical simulations based on the coupled generalized nonlinear Schrödinger equations. Moreover, the simulation results correspond qualitatively with the experimentally acquired dependences of the output dual-core extinction Ratio on excitation energy and wavelength. In the case of 1800 nm fast core excitation, narrow band spectral intensity switching between the output channels was registered with contrast of 23 dB. The switching was achieved by the change of the excitation pulse energy in sub-nanojoule region. The performed detailed analysis of the nonlinear balancing of dual-core asymmetry in solitonic propagation regime opens new perspectives for the development of ultrafast nonlinear all-optical switching devices.
We demonstrate narrow band spectral intensity switching in dual-core photonic crystal fibers made of highly nonlinear glass under femtosecond excitation. The fibers expressed dual-core asymmetry, thus the slow and fast fiber cores were unambiguously distinguished according to their dispersion profiles. The asymmetry effect on the dual-core Propagation in anomalous dispersion region was studied both experimentally and numerically. The experimental study was carried
out using femtosecond laser amplifier system providing tunable pulses in range of 1500 nm - 1800 nm. The obtained results unveiled, that it is possible to improve nonlinearly the coupling between the two waveguides by excitation of the fast fiber core. The results were obtained in regime of high-order soliton propagation and were verified numerically by the coupled generalized nonlinear Schrödinger equations model. The spectral analysis of the radiation transferred to the non-excited core revealed the role of effects such as third order dispersion, soliton compression and spectral dependence of the coupling efficiency. The simulation results provide reasonable agreement with the experimentally observed spectral evolutions in the both fiber cores. Under 1800 nm excitation, narrow band spectral intensity switching was registered with contrast of 23 dB at 10 mm fiber length by changing the excitation pulse energy in sub-nanojoule range.
Nonlinear propagation of ultrafast near infrared pulses in anomalous dispersion region of dual-core photonic crystal fiber was studied. Polarization tunable soliton-based nonlinear switching at multiple non-excitation wavelengths was demonstrated experimentally for fiber excitation by 100 fs pulses at 1650 nm. The highest-contrast switching was obtained with the fiber length of just 14 mm, which is significantly shorter compared to the conventional non-solitonic in-fiber switching based on nonlinear optical loop mirror. Advanced numerical simulations show good agreement with the experimental results, suggesting that the underlying dual-core soliton fission process supports nonlinear optical switching and simultaneous pulse compression to few-cycle durations at the level of 20 fs.
Nonlinear ultrafast switching based on soliton self-trapping in dual-core photonic crystal fibre
(2016)
In this paper, we present a systematic numerical study of a novel ultrafast nonlinear switching
concept based on soliton self-trapping in dual-core (DC) photonic crystal fibre (PCF).
The geometrical parameters of highly-nonlinear (HN) DC microstructure are optimized
with regard to desired linear and nonlinear propagation characteristics. The comparable
magnitude of fibre coupling length and soliton period is identified as a key condition for
presented switching concept. The optimized DC PCF design is subjected to detailed nonlinear
numerical study. Complex temporal-spectral-spatial transformations of 100 fs hyperbolic
secant pulse at 1550 nm in the DC PCF are studied numerically employing a model based on
coupled generalized nonlinear Schrödinger equations solved by a split-step Fourier method.
For the optimized DC structure, mutual interplay of solitonic and coupling processes gives
rise to nonlinear switching of self-trapped soliton. The output channel (fibre core) for the
generated soliton can be controlled via the input pulse energy. For vertical polarization, the
optimal soliton switching with extinction ratio contrast of 32.4 dB at 10.75 mm propagation
distance is achieved. Even better switching contrast of 34.8 dB can be achieved for horizontal
polarization at optimal propagation distance of 10.25 mm. Besides energy-controlled soliton
self-trapping switching, the fibre supports also nonlinear polarization switching with soliton
switching contrast as high as 37.4 dB. The proposed fibre holds a high application potential
allowing efficient ultrafast switching of sub-nanojoule pulses at over-Tb/s data rates requiring
only about 1 cm fibre length.
The improvement potential of ultrafast all-optical switching by soliton self-trapping, using all-solid dual-core fibres with high index contrast, was analyzed numerically. The study of the femtosecond nonlinear propagation was performed based on coupled generalised nonlinear Schrödinger equations considering three fibre architectures: homogeneous cladding all-solid, photonic crystal air-glass, and photonic crystal all-solid. The structural geometries of all three architectures were optimised in order to support high-contrast switching performance in the C-band, considering pulse widths at the 100 fs level. Comparing the three structural alternatives, the lowest switching energies at common excitation parameters (1700 nm and 70 fs pulses) were predicted for the homogeneous cladding dual-core structure. Further optimization of the excitation wavelength and pulse width resulted in lower switching energies and simultaneous improvement of the switching contrasts at the combination of 1500 nm, 75 fs pulses and a fibre length of 43 mm. The spectral aspect in this optimised case expresses a broadband and uniform switching character with a span of over 200 nm and a contrast exceeding 30 dB at more frequency channels.