Observation of pulse-phase shift in a highly-nonlinear slotted photonic crystal waveguide (original) (raw)
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Characterization of slotted photonic crystal waveguide and its application in nonlinear optics
Superlattices and Microstructures, 2017
Characteristics of slotted photonic crystal waveguides (SPCWs) are highly dependent on width and refractive index of the slot. This dependence has been explored in this paper, by calculating the respective dispersion diagrams using the three-dimensional full-vector Plane Wave Expansion method. Group index and effective modal area of the SPCWs have been calculated, subjected to these variations, to characterize its slow light performance and confinement respectively. The results are expressed as a function of normalized frequency and, hence, can characterize a SPCW of arbitrary scale and operating wavelength of interest. The analysis presented in this paper is able to save a significant computation time of the researchers working in this domain. Finally, the enhancement of the stimulated Raman scattering (SRS) has been analysed in a SPCW, to characterize its nonlinear performance, by using a low-index highly nonlinear material in the slot. A net gain of the order of 11 dB is found in a ∼ 7 µm long SPCW.
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).
Photonics Research, 2016
We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption (TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slowdown factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index (n G) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from n G 10 to n G 50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics.
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.
Soliton propagation with cross-phase modulation in silicon photonic crystal waveguides
Journal of the Optical Society of America B, 2013
An effort was conducted to numerically determine, using the Nonlinear Schrödinger Split-Step Fourier method, if using cross phase modulation could cause temporal soliton pulse propagation in a silicon slow-light photonic crystal waveguide shorter than a millimeter. The simulations demonstrated that due to the higher powers and shorter scales of photonic crystals, two-photon absorption would cause an optical soliton pulse to be extremely dissipative. The model demonstrated, however, that by utilizing cross-phase modulation, it is possible to sustain a compressed soliton pulse within a silicon photonic crystal waveguide subjected to two-photon absorption over longer relative distances.
Nano Letters, 2010
We demonstrate experimentally all-optical switching on a silicon chip at telecom wavelengths. The switching device comprises a compact ring resonator formed by horizontal silicon slot waveguides filled with highly nonlinear silicon nanocrystals in silica. When pumping at power levels about 100 mW using 10 ps pulses, more than 50% modulation depth is observed at the switch output. The switch performs about 1 order of magnitude faster than previous approaches on silicon and is fully fabricated using complementary metal oxide semiconductor technologies.
Low TPA and free-carrier effects in silicon nanocrystal-based horizontal slot waveguides
2012
Abstract: We present the characterization of the ultrafast nonlinear dynamics of a CMOS-compatible horizontal-slot waveguide with silicon nanocrystals. Results are compared to strip silicon waveguides, and modeled with nonlinear split-step calculations. The extracted parameters show that the slot waveguide has weaker carrier effects and better nonlinear figure-of-merit than the strip waveguides.
All-optical Switching Structure Using Nonlinear Photonic Crystal Directional Coupler
2008
In this paper, a new all-optical switching structure is proposed and analyzed. Switching is accomplished by embedded Kerr nonlinear rods in the coupling region of a photonic crystal directional coupler. We show that by modifying the supermodes dispersion curves, the switch length can be reduced 22% with respect to similar structures. Finite-Difference Time-Domain and Plane Wave Expansion methods are used to analyze the device characteristics. The results show that the transmission efficiency of the proposed structure has been significantly improved.