On-Chip Broadband Mid-Infrared Supercontinuum Generation Based on Highly Nonlinear Chalcogenide Glass Waveguides

Di Xia,Ying Zhu,Huanjie Cheng,Zelin Yang,Yufei Huang,Linghao Liu,Haiyan Shang,Pingyang Zeng,Bin Zhang,Zhaohui Li,Mingjie Zhang

doi:10.3389/fphy.2021.598091

Abstract

On-chip mid-infrared (MIR) supercontinuum generation (SCG) covering the molecular functional spectral region (3–12 μm) offers the advantages of robustness, simplicity, and compactness. Yet, the spectral range still cannot be expanded beyond 10 μm. In this study, on-chip ultrabroadband MIR SCG in a high numerical aperture chalcogenide (ChG) waveguide is numerically investigated. The ChG waveguide with a Ge-As-Se-Te core and Ge-Se upper and lower cladding is designed to optimize the nonlinear coefficients and dispersion profile. Assisted by dispersive wave generation in both short- and long-wavelength range, broadband SCG ranging from 2 to 13 µm is achieved. Besides, a fabrication scheme is proposed to realize precise manipulation of dispersion design. Such results demonstrate that such sources are suitable for compact, chip-integrated molecular spectroscopy applications.

Highlights

Capturing the distinctive spectral fingerprints of molecules in the infrared (IR) region is of vital importance in molecular spectroscopy applications for environmental and health monitoring [1,2,3]
The high-order soliton dynamics will be induced when the pulse laser propagates in a flat and low anomalous group velocity dispersion (GVD) region [19], facilitating a self-phase modulation (SPM) enabling spectral broadening and temporal compression, and the degree is proportional to the soliton number [20]
The second ZWD is moved as waveguide structure changes

Summary

INTRODUCTION

Capturing the distinctive spectral fingerprints of molecules in the infrared (IR) region is of vital importance in molecular spectroscopy applications for environmental and health monitoring [1,2,3]. A femtosecond pulse laser is used to pump the nonlinear waveguide which has a wide transmission range and high nonlinear refractive index (n2) with dispersion engineered for broadband SCG. SCG occurs when a sufficiently powerful femtosecond pulse propagates through nonlinear nanophotonic waveguides and generally experiences a temporal compression and spectral broadening. The high-order soliton dynamics will be induced when the pulse laser propagates in a flat and low anomalous group velocity dispersion (GVD) region [19], facilitating a self-phase modulation (SPM) enabling spectral broadening and temporal compression, and the degree is proportional to the soliton number [20]. As for ChG-based SCG, the laser-induced damage threshold (LDT) is important when dumping femtosecond pulse with high peak power into the waveguides. Where Pcr is the critical average powers when the observable modification on the surface is induced, Ppeak, D, R, and τ are the corresponding peak power, diameter of the beam spot, repetition rate, and pulse duration, respectively

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT