Design of two-dimensional photonic crystal nanocavities with low-refractive-index material cladding

Abstract

We have theoretically investigated two-dimensional photonic crystal (2D PC) nanocavities with low-refractive-index (low- n) material cladding using a 3D finite-difference time-domain method. When the refractive index of the cladding is increased from 1 to 1.535, corresponding to that of organic polymers, the Q factor markedly decreases (Q<103). We finely adjusted the positions of the holes at both edges of the 2D PC nanocavities. The Q factor can be increased by a factor of up to 21 (Q>104) by shifting the neighboring four pairs of holes inward by suitable amounts. In addition, we examined the real and wavevector space distributions of the resonant modes. We revealed significant design rules based on single and double Gaussian envelope functions, which can be used to effectively and flexibly develop and finely adjust the optical properties of 2D PC nanocavities with low- n material cladding.

A Simple Coupled-Bloch-Mode Approach to Study Active Photonic Crystal Waveguides and Lasers

“…Rigorous approaches to analyze PhC devices, such as FDTD [4], [12] or RCWA [13], [14], [15], are time-and memoryconsuming and cannot always provide an intuitive understanding of the physical phenomena into play. The aim of this paper is to present an alternative and simple approach for analyzing active PhC LDWGs and lasers based on this type of waveguides.…”

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].…”

“…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]. A fully clad PhC L3 nanocavity completely embedded in glass (with all holes infiltrated by the glass) was numerically analyzed and a Q factor of 1100 was obtained [16].…”

“…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].…”