Air-mode photonic crystal ring resonator on silicon-on-insulator

Abstract

In this report, we propose and demonstrate an air-mode photonic crystal ring resonator (PhCRR) on silicon-on-insulator platform. Air mode is utilized to confine the optical field into photonic crystal (PhC) air holes, which is confirmed by the three-dimensional finite-difference time-domain simulation. PhCRR structure is employed to enhance the light-matter interaction through combining the whispering-gallery mode resonance of ring resonator with the slow-light effect in PhC waveguide. In the simulated and measured transmission spectra of air-mode PhCRR, nonuniform free spectral ranges are observed near the Brillouin zone edge of PhC, indicating the presence of the slow-light effect. A maximum group index of 27.3 and a highest quality factor of 14600 are experimentally obtained near the band edge. Benefiting from the strong optical confinement in the PhC holes and enhanced light-matter interaction in the resonator, the demonstrated air-mode PhCRR is expected to have potential applications in refractive index sensing, on-chip light emitting and nonlinear optics by integration with functional materials.

Slow light in mass-produced, dispersion-engineered photonic crystal ring resonators

“…The highest PhCRR intrinsic Q-factor of ≈83,800 was found at the two-fold mode of a 20µm-diameter PhCRR. To the extent of our knowledge, this is the highest reported quality factor in either the dielectric or air bands of a fabricated PhCRR [17,18,24], confirming the validity of our particular design and fabrication methods. Quality Factor Slowdown Factor (n Group /n Phase ) Fig.…”

“…This attribute makes PhCRRs particularly suitable for the observation of non-linear optical phenomena. It is worth noting that the above design method can easily be generalized so as to target resonances on the "air" band of the PhC waveguide, where the strength of the field is concentrated in the air holes of the PhC lattice [18]. This particular field configuration may prove interesting for biological or chemical sensors, where strong light-matter interactions can enhance the detection of analytes.…”

“…Previous PhCRRs have been fabricated on the SOI platform using electron-beam lithography; Lee et. al [17] first demonstrated non-uniform mode spacing indicative of slow-light wave propagation in fabricated photonic crystal ring resonators with a maximum reported Q-factor of Q ∼ 2000 and group index of n g ∼ 20, while Gao et al [18] successfully decreased optical losses by nearly an order of magnitude, with a maximum reported Q-factor of Q ∼ 14,800 and group index of n g ∼ 28. Accordingly, the high fabrication resolution of electron-beam lithography has been proven acceptable for fabricating the nanoscale features of a PhCRR.…”

Photonic crystal microring resonator for label-free biosensing

“…1(c), which shows that the field enhancement in the air holes occurs near the Si-air-interface; hence, no additional sensitivity enhancement is experienced by analyte that fills the holes compared to analyte that only binds on the surface of the holes. The experimental results reported here are based on a PhCR with resonances near the dielectric band edge; it is expected that an even higher sensitivity may be obtained if a resonance near the air band edge is used [25,31].…”

A Highly Accurate Refractive Index Sensor with Two Operation Modes Based on Photonic Crystal Ring Resonator

“…For instance, the first measurement of RI with sensitivity, Q factor, and size of 200 nm/RIU, 400, and 10 µm 2 , respectively has been presented in 2004 . So far, many theoretical and experimental studies on PC‐based RI sensors have been reported . The optical properties of RI sensors such as Q factor, detection range, and sensitivity highly depend on the structural parameters.…”