Optimization of Q-factor in nonlinear planar photonic crystal nanocavity incorporating hybrid silicon/polymer material

Abstract

We present a novel design for a high quality (Q)-factor, nonlinear planar photonic crystal (PhC) nanocavity incorporating a silicon/polymer material that is well suited to ultrafast all-optical switching. The hybrid nanocavity is created in the centre of a triangular lattice planar PhC made from silicon using the three-missing-holes point defect (L3). It is formed by infiltrating the air hole array of the PhC with polymer and by depositing a polymer layer on top of a PhC membrane. To determine the hybrid nonlinear cavity performance, we analyze the dependence of the refractive index (RI) of the top cladding on the Q-factor and resonant wavelength. The results show that, when the top cladding RI is increased from 1.5 to 1.6, corresponding to that of polymer materials, the Q-factor decreases markedly (Q < 10 3 ). Optimization of the hybrid nonlinear silicon/polymer cavity design by modulating the structure parameters yields a high Qfactor of 54 000 with a small modal volume across the telecommunications band. In addition, the field distribution of the resonant mode indicates that the radiation loss is sufficiently small. Due to the overwhelmingly large Kerr nonlinearity of polymer over silicon, this structure configuration design shows considerable promise as regards the realization of ultrafast response speed in small-sized all-optical switching integrated devices.

Numerical analysis of subwavelength field effects in photonic crystal slab cavities

“…By minor additional refinements in the design, the Q factor can be increased significantly. They consist of shifting and reducing radii of near cavity holes, as shown for L3 cavities [13][14][15][16], H0 cavities [15,17] and L3 cavities surrounded by different media [18,19].…”

Optical properties of point-defect nanocavity implemented in planar photonic crystal with various low refractive index cladding materials

“…One well-known class of PhC structure is two-dimensional mode, with the specific aim of optimizing the ratio of Q factor to modal volume. To achieve mechanical stability of L3 cavities in 2D PhCs with low-RI cladding, some papers have reported the Q factors of structures with full and asymmetric cladding [15,16,22,23]. By using organic polymer cladding, a resonant mode with a Q factor of 14,000 was designed in PhC L3 cavity with low-RI material cladding on a silicon wafer substrate [15].…”

“…For some applications may need SiO 2 or organic polymer clad PhC cavities, the Q factor of the designed cavities is higher than 10 4 . While cavities with symmetric cladding have been studied, our previous work [23] presented an example of a L3 cavity with asymmetric low-RI material cladding. The designed hybrid L3 nanocavity is formed by infiltrating the air-hole array of the Si PhC with a polymer and depositing a polymer layer on top of the PhC membrane.…”

“…Furthermore, when 2D PhCs are fully cladded by air, continuous oxidation and unavoidable contamination can affect the structural characteristics of the photonic device [13]. To address these problems, various investigations have focused on planar PhC nanocavities partially or fully clad by low-RI materials [14][15][16][17][18][19][20][21][22][23].In particular, cavities made of planar PhCs with three missing holes linearly arranged (L3) are attracting considerable interest for applications involving high-qualityfactor (high-Q) nanocavities because these structures can selectively confine light of various wavelengths. PhC L3 nanocavities with high-Q factors and a small cubic-wavelength volume are used for all-optical switching [8], lowthreshold lasing [4-6], cavity quantum electrodynamics [7,10], and to control ultrafast laser pulses [24].…”

“…Furthermore, when 2D PhCs are fully cladded by air, continuous oxidation and unavoidable contamination can affect the structural characteristics of the photonic device [13]. To address these problems, various investigations have focused on planar PhC nanocavities partially or fully clad by low-RI materials [14][15][16][17][18][19][20][21][22][23].…”