Fabrication of the high-Q Si3N4 microresonators for soliton microcombs

Abstract

The microresonator-based soliton microcomb has shown a promising future in many applications. In this work, we report the fabrication of high quality (Q) Si 3 N 4 microring resonators for soliton microcomb generation. By developing the fabrication process with crack isolation trenches and annealing, we can deposit thick stoichiometric Si 3 N 4 film of 800 nm without cracks in the central area. The highest intrinsic Q of the Si 3 N 4 microring obtained in our experiments is about 6 × 10 6 , corresponding to a propagation loss as low as 0.058 dBm/cm. With such a high Q film, we fabricate microrings with the anomalous dispersion and demonstrate the generation of soliton microcombs with 100 mW on-chip pump power, with an optical parametric oscillation threshold of only 13.4 mW. Our Si 3 N 4 integrated chip provides an ideal platform for researches and applications of nonlinear photonics and integrated photonics.

Synchronization of Optomechanical Oscillator and Breathing Soliton

“…The Si 3 N 4 microring resonator with the cross-section of 720 nm × 2400 nm and the free spectral range of 100 GHz is fabricated with a substractive process, more fabrication details can be found in refs. [18,45]. Figure 2a shows the typical transmission spectrum of the microring from 1510 to 1630 nm.…”

On‐chip terahertz whispering gallery mode resonator with high‐Q based on multislot waveguide

“…10,11 In this case, the performance of resonators is typically limited by a relatively large absorption loss (e.g., 0.025 cm −1 in 0.4 THz ~2 THz for HRFZ-Si, which is two orders of magnitude larger than the absorption loss of optical materials in near-infrared light). 10,11,[16][17][18][19][20][21] As a result, a relatively low-quality factor (e.g., typically at the order of 10 3 with bending radius of 3mm)of the onchip THz resonator is generally reported, which highly limits the application of on-chip THz sensors. 10,11 At the same time, based on the traditional uniform waveguide coupling or spatial optical coupling theory, coupling spectral width is small (typically at the order of 0.01THz) and the resonance curve varies sharply with frequency.…”

“…Generally, high‐resistivity float zone silicon (HRFZ‐Si) ring cavity based on ridge waveguides are fabricated by CMOS technology 10,11 . In this case, the performance of resonators is typically limited by a relatively large absorption loss (e.g., 0.025 $${\text{cm}}^{-1}$$ in 0.4 THz ~ 2 THz for HRFZ‐Si, which is two orders of magnitude larger than the absorption loss of optical materials in near‐infrared light) 10,11,16–21 . As a result, a relatively low‐quality factor (e.g., typically at the order of $$1{0}^{3}$$ with bending radius of 3mm)of the on‐chip THz resonator is generally reported, which highly limits the application of on‐chip THz sensors 10,11 .…”

High energy efficiency soliton microcomb generation in high coupling strength, large mode volume, and ultra-high-Q micro-cavity

“…However, the energy conversion efficiency (ECE) of DKS microcombs is quite low, which casts doubt over their practical utilization [7][8][9] . There are many reasons for such low ECE.…”