In this Letter, the effects of material/structure parameters of photonic crystal (PhC) parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the PhC leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact PhC 1.31/1.55 μm wavelength division multiplexer (WDM)/demultiplexer with simple structure is proposed, where the output power ratios are more than 24 dB. This WDM can multiplex/demultiplex other light waves efficiently.

We introduce a family of slot photonic crystal waveguides (SPhCWs) for the hybrid integration of low-index active materials in silicon photonics with energy-confinement factors of ～30% in low-index regions. The proposed approach, which is based on a periodic indentation of the etched slot in the middle of the SPhCW, makes it possible to reconcile a simultaneously narrow and wide slot for exploiting the two modes of even symmetry of a SPhCW. The resulting mode-selection mechanism allows a flexible choice of the modes to be used. Furthermore, the proposed structure offers tremendous flexibility for adjusting the dispersive properties of the slot-confined modes, in particular of their slow-light effects. Flat band slow light in a bandwidth of about 60 nm with a group velocity dispersion factor |β2| below 1 ps2/mm is numerically demonstrated by this approach, corresponding to a normalized delay bandwidth product of around 0.4. These results, obtained from hollow-core periodic waveguides that are directly designed in view of hybrid integration of active materials in mechanically robust structures (not based on free-standing membranes) could pave the way for the realization of on-chip slow-light bio-sensing, active hybrid-silicon optoelectronic devices, or all-optical hybrid-silicon nonlinear functionalities.

This Letter introduces the design and simulation of a microstrip-line-based electro-optic (EO) polymer optical phase modulator (PM) that is further enhanced by the addition of photonic crystal (PhC) structures that are in close proximity to the optical core. The slow-wave PhC structure is designed for two different material configurations and placed in the modulator as a superstrate to the optical core; simulation results are depicted for both 1D and 2D PhC structures. The PM characteristics are modeled using a combination of the finite element method and the optical beam propagation method in both the RF and optical domains, respectively. The phase-shift simulation results show a factor of 1.7 increase in an effective EO coefficient (120 pm/V) while maintaining a broadband bandwidth of 40 GHz.

A novel H-plane cross-shaped circulator based on magneto-photonic crystals is experimentally investigated. The band gap of the TE mode for the photonic crystals is calculated by the plane wave expansion method. The transmission characteristics of the circulator are simulated by the finite element method. We perform the experiments in the microwave regime to validate the numerical results. At the central frequency of 10.15 GHz, the measured isolation and insertion loss of the circulator reaches 30.2 and 3.93 dB, respectively. The bandwidth of the circulator is about 550 MHz. The optimal experimental value of isolation is higher than the numerical value.

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 slow-down 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 (nG) 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 nG
10 to nG
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.