A silicon nitride microdisk resonator with a 40-nm-thin horizontal air slot

Shinyoung Lee,Seok Chan Eom,Chul Huh,Jee Soo Chang,Gun Yong Sung,Jung H Shin

doi:10.1364/oe.18.011209

Abstract

We design and fabricate pedestal-type, 15 microm diameter silicon nitride microdisk resonators on Si chip with horizontal air-slot using selective wet etching between Si, SiO2, and SiNx. As the slot structure is determined by deposition process, air slots that are as thin as 40 nm and as deep as 5 microm with ultra-smooth slot surfaces can easily be fabricated with photolithography only. Fundamental TM-like slot mode in which the E-field is greatly enhanced within slot was observed with an intrinsic Q factor of approximately 34,000 (lambdares=1523.7 nm) and energy overlap in slot region of 21.6%.

Highlights

Light confinement in nm-size region is essential for highly sensitive and compact devices for optoelectronics
We design and fabricate pedestal-type, 15 μm diameter SiNx microdisk resonators on Si chip with horizontal air-slot formed by selective wet etching between Si, SiO2, and SiNx
Fundamental TM-like slot mode in which the Efield is greatly enhanced within slot was observed with an intrinsic Q factor of ~34,000 at the resonance wavelength 1523.7nm and energy overlap in slot region of 21.6%

Summary

Introduction

Light confinement in nm-size region is essential for highly sensitive and compact devices for optoelectronics. Several applications such as sensing [2], optical modulation using enhanced nonlinear effect [3,4], and optical manipulation were reported using waveguides and resonators based on slot-structures [5,6] These works utilized vertical-slot structures whose slot consisted of a narrow, vertical trench in a high-index waveguide. Such a structure has the advantage of an open slot into which functional materials can be introduced for enhanced photon-matter interaction confined in a sub-wavelength region. Fundamental TM-like slot mode in which the Efield is greatly enhanced within slot was observed with an intrinsic Q factor of ~34,000 at the resonance wavelength 1523.7nm and energy overlap in slot region of 21.6%

Device fabrication

Results and discussion

Conclusion