Abstract
A more than 1.5 octave-spanning mid-infrared supercontinuum (1.2 to 3.6 μm) is generated by pumping a As2S3-silica "double-nanospike" waveguide via a femtosecond Cr:ZnS laser at 2.35 μm. The combination of the optimized group velocity dispersion and extremely high nonlinearity provided by the As2S3-silica hybrid waveguide enables a ~100 pJ level pump pulse energy threshold for octave-spanning spectral broadening at a repetition rate of 90 MHz. Numerical simulations show that the generated supercontinuum is highly coherent over the entire spanning wavelength range. The results are important for realization of a high repetition rate octave-spanning frequency comb in the mid-infrared spectral region.
Highlights
Frequency combs in the mid-infrared spectral region of 2-20 μm (500-5000 cm−1) are highly desirable for high precision spectroscopy, because many molecules possess strong characteristic vibrational transitions in this domain (“molecular fingerprint region”) [1]
The combination of the optimized group velocity dispersion and extremely high nonlinearity provided by the As2S3-silica hybrid waveguide enables a ~100 pJ level pump pulse energy threshold for octave-spanning spectral broadening at a repetition rate of 90 MHz
Efficient and coherent spectral broadening is highly desirable, especially for the case of high repetition rate frequency comb generation, where the energy of a single pump pulse energy is limited by the average power available
Summary
Frequency combs in the mid-infrared (mid-IR) spectral region of 2-20 μm (500-5000 cm−1) are highly desirable for high precision spectroscopy, because many molecules possess strong characteristic vibrational transitions in this domain (“molecular fingerprint region”) [1]. Efficient (i.e., low threshold energy) and coherent spectral broadening is highly desirable, especially for the case of high repetition rate frequency comb generation, where the energy of a single pump pulse energy is limited by the average power available This normally requires a stable mid-IR ultrafast laser as the pump source, combined with a highly nonlinear waveguide with suitable dispersion characteristics. Chromium-doped chalcogenide (Cr:ZnS/Cr:ZnSe) based lasers, often called the “Ti-sapphires of the infrared” due to their very broad absorption and emission bands, have recently matured to provide femtosecond performance in all respects comparable with Ti:sapphire lasers [12,13,14] As such, they represent ideal compact and stable sources for generation of high quality coherent octavespanning supercontinua in the mid-IR. The extremely high nonlinearity of the hybrid waveguide, together with the greatly enhanced coupling efficiency obtained through the double-nanospike structure and the high peak power and good pulse quality of the Cr:ZnS laser, enables octave-spanning coherent SC generation with a threshold pulse energy of hundreds of pJ
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
