Soliton propagation with cross-phase modulation in silicon photonic crystal waveguides (original) (raw)
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Optics Express, 2015
We demonstrate the temporal and spectral evolution of picosecond soliton in the slow light silicon photonic crystal waveguides (PhCWs) by sum frequency generation cross-correlation frequency resolved optical grating (SFG-XFROG) and nonlinear Schrödinger equation (NLSE) modeling. The reference pulses for the SFG-XFROG measurements are unambiguously pre-characterized by the second harmonic generation frequency resolved optical gating (SHG-FROG) assisted with the combination of NLSE simulations and optical spectrum analyzer (OSA) measurements. Regardless of the inevitable nonlinear two photon absorption, high order soliton compressions have been observed remarkably owing to the slow light enhanced nonlinear effects in the silicon PhCWs. Both the measurements and the further numerical analyses of the pulse dynamics indicate that, the free carrier dispersion (FCD) enhanced by the slow light effects is mainly responsible for the compression, the acceleration, and the spectral blue shift of the soliton.
Applied optics, 2016
By orthogonally dual-shifting the air-hole rows in the triangular photonic crystal waveguide, a novel finely engineered slow light silicon photonic crystal waveguide is designed for higher-order temporal solitons and ultrashort temporal pulse compression with a large fabrication tolerance. The engineering of dispersion provides the waveguide with a wide wavelength range with only low anomalous dispersion covering, which makes the compression ratio wavelength-independent and stable even under ultralow input pulse energy. The simulation results are based on nonlinear Schrödinger equation modeling, which demonstrates that the input picosecond pulses in the broad wavelength range with ultralow pJ pulse energy can be stably compressed by a factor of 6 to higher-order temporal solitons in a 250 μm short waveguide.
Temporal solitons and pulse compression in photonic crystal waveguides
2010
Solitons are nonlinear waves that exhibit invariant or recurrent behaviour as they propagate. Precise control of dispersion and nonlinear effects governs soliton propagation and, through the formation of higher-order solitons, permits pulse compression. In recent years the development of photonic crystals-highly dispersive periodic dielectric media-has attracted a great deal of attention due to the facility to engineer and enhance both their nonlinear and dispersive effects. In this Article, we demonstrate the first experimental observations of optical solitons and pulse compression in ∼1-mm-long photonic crystal waveguides. Suppression of two-photon absorption in the GaInP material is crucial to these observations. Compression of 3-ps pulses to a minimum duration of 580 fs with a simultaneously low pulse energy of ∼20 pJ is achieved. These small-footprint devices open up the possibility of transferring soliton applications into integrated photonic chips.
Slow light enhancement of nonlinear effects in silicon engineered photonic crystal waveguides
We report nonlinear measurements on 80µm silicon photonic crystal waveguides that are designed to support dispersionless slow light with group velocities between c/20 and c/50. By launching picosecond pulses into the waveguides and comparing their output spectral signatures, we show how self phase modulation induced spectral broadening is enhanced due to slow light. Comparison of the measurements and numerical simulations of the pulse propagation elucidates the contribution of the various effects that determine the output pulse shape and the waveguide transfer function. In particular, both experimental and simulated results highlight the significant role of two photon absorption and free carriers in the silicon waveguides and their reinforcement in the slow light regime.
Slow Light Enhanced Nonlinear Optics in Silicon Photonic Crystal Waveguides
—We present a summary of our recent experiments showing how various nonlinear phenomena are enhanced due to slow light in silicon photonic crystal waveguides. These nonlinear processes include self-phase modulation (SPM), two-photon absorption (TPA), free-carrier related effects, and third-harmonic generation, the last effect being associated with the emission of green visible light, an unexpected phenomenon in silicon. These demonstrations exploit photonic crystal waveguides engineered to support slow modes with a range of group velocities as low as c/50 and, more crucially, with significantly reduced dispersion. We discuss the potential of slow light in photonic crystals for realizing compact nonlinear devices operating at low powers. In particular, we consider the application of SPM to all-optical regeneration, and experimentally investigate an original approach, where enhanced TPA and free-carrier absorption are used for partial regeneration of a high-bit rate data stream (10 Gb/s).
APL Photonics, 2021
Self-steepening (SS) is enhanced by slow-light effects in photonic crystal waveguides (PhCWs), with coefficients as large as hundreds of femtoseconds, and it plays an important role in temporally compressed solitons with narrow widths. Here, we investigate the soliton evolution in silicon PhCWs through experiments and numerical simulations; the simulated results agree well with the experimental measurements and help in revealing the physical mechanism of high-order soliton evolution. The dual opposite effects of giant anomalous SS on temporal soliton compression are demonstrated for the first time, i.e., the SS weakens or improves the compression competing with the effects of third-order dispersion (TOD) through two different physical mechanisms. It is also found that SS flattens or steepens the pulse leading edge depending on the strength of the positive TOD perturbation. These results promote the understanding of high-order solitons and can help with the design of suitable dispersion engineered silicon waveguides for superior on-chip temporal pulse compression for optical interconnects, data processing, and microwave photonics.
Observation of Soliton Pulse Compression in Photonic Crystal Waveguides
Conference on Lasers and Electro-Optics 2010, 2010
Soliton-effect pulse compression and propagation has been experimentally demonstrated in the temporal domain in fibers [1], fiber Bragg gratings [2], photonic crystal fibers (PhCF) [3-6], photonic nanowires [7] and in the spectral domain of integrated channel waveguides [8, 9]. Here we demonstrate the first experimental observations of soliton-effect pulse compression in semiconductor photonic crystal waveguides (PhCWG) in the temporal domain. Pulse compression in the PhCWGs occurs due to the interaction between a strong group-velocity dispersion (GVD) [10] and slow-light enhanced self-phase modulation (SPM) in the periodic dielectric media [11]. Compression of 3 ps input pulses to a minimum pulse duration of 580 fs (~10 pJ) is achieved. The small modal area A eff ~ 10 -13 m 2 combined with a slow-light enhanced optical field allow for ultra-low threshold (~GW/cm 2 ) pulse compression at millimeter length scales. These results open the way for femtosecond and soliton applications on the chip scale. Periodic dielectric structures have long been known to have extremely large dispersion thus enabling observation of soliton effects at centimeter length scales [2, 12-14]. The decreased interaction length, however, requires a correspondingly larger intensity-dependent nonlinear effect to match the strength of the dispersion. Increasing the optical intensity inside the waveguide is accomplished through: (a) direct input of larger peak powers; (b) decreasing the effective modal area [7-9]; or, most recently, (c) via dispersion-engineered periodic slow-light structures [10, 11]. At the so-called slow-light frequencies of PhCWGs, the light experiences a longer effective path length through the lattice via multiple Bragg reflections, leading to an enhanced local field density. The enhanced field scales inversely with the group velocity, thus
Slow light enhancement of nonlinear effects in photonic crystal waveguides
2010
We report nonlinear measurements on 80Pm silicon photonic crystal waveguides that are designed to support dispersionless slow light with group velocities between c/20 and c/50. By launching picosecond pulses into the waveguides and comparing their output spectral signatures, we show how self phase modulation induced spectral broadening is enhanced due to slow light. Comparison of the measurements and numerical simulations of the pulse propagation elucidates the contribution of the various effects that determine the output pulse shape and the waveguide transfer function. In particular, both experimental and simulated results highlight the significant role of two photon absorption and free carriers in the silicon waveguides and their reinforcement in the slow light regime.
Self-frequency blueshift of dissipative solitons in silicon-based waveguides
Physical Review A, 2013
We analyze the dynamics of dissipative solitons in silicon on insulator waveguides embedded in a gain medium. The optical propagation is modeled through a cubic Ginzburg-Landau equation for the field envelope coupled with an ordinary differential equation accounting for the generation of free carriers owing to two-photon absorption. Our numerical simulations clearly indicate that dissipative solitons accelerate due to the carrier-induced index change and experience a considerable blue-shift, which is mainly hampered by the gain dispersion of the active material. Numerical results are fully explained by analytical predictions based on soliton perturbation theory.
Nonlinear slow light propagation in photonic crystal slab waveguides: theory and practical issues
Photonic Crystal Materials and Devices X, 2012
In this paper, we consider the propagation of slow light optical pulses inside photonic crystal slab waveguides (PCSW) both from a theoretical and an application point-of-view. The numerical model used relies on a nonlinear envelope propagation equation that includes the effects of second and third order dispersion, optical losses and self phase modulation. Pulse propagation is examined both in the linear and nonlinear regime. It is numerically shown that for rates of 10Gb/s, the order of nanosecond delays can be achieved through the PCSW defect modes without excessive pulse broadening in the nonlinear regime. In the nonlinear case, it is shown that soliton pulses exhibit less broadening than pulses in the linear case. In comparing the linear and the non-linear case we consider launching pulses with the same initial full width at half maximum or the same RMS width. The influence of optical losses on the soliton pulse broadening factor is also incorporated and discussed providing a more practical perspective. The results demonstrate the potential of implementing a variety of linear and nonlinear signal processing applications in PCSWs, such as optical buffering.