An Ultra-Violet Microcomb
Abstract
Dual comb spectroscopy provides broad-band and fast high-resolution analysis of optical absorp- tion spectra. Moreover, the combination of CARS with dual comb analysis extends this powerful characterization tool into the realm of vibrational spectra. A recent development, the soliton mi- crocomb, offers the possibility of miniaturizing dual-comb spectroscopic methods by transferring the comb generation process to a chip. This presents an ideal application of microcombs as a full dual-comb system based on conventional frequency combs consumes 2X the footprint of a single comb while, in principle, dual microcombs can share a single semiconductor chip. Also, the same chip can furnish needed integrated electronics to control the dual comb system. Using 1.55 micron pumping we have initiated an effort to test the feasibility of dual-comb spec- troscopy using microcomb soliton sources. Preliminary results of this effort are described below and show that the soliton microchip platform is well suited for dual comb spectroscopy. Not only is it possible to observe absorption lines in the comb spectra, but the soliton spectrum is very predicable so that spectral calibration is possible. We propose to build-on this preliminary effort as follows: 1. A 1-micron soliton microcomb will be developed. The microcomb will use a silica ridge waveguide resonator that is dispersion engineered to enable anomalous dispersion at the 1 micron pumping wavelength. Preliminary tests of straight waveguides using this design confirm the anomalous nature of dispersion in our waveguide. The focus will be to implement the waveguide design in a resonator geometry, optimize the design to knock-out modal avoided crossings, and demonstrate soliton emission. 2. The emission band of the 1-micron soliton comb will be greatly extended by engineering the ridge waveguide resonator for dispersive wave generation. A series of designs will be implemented so that coherent dispersive wave emission in the ultra-violet is possible. Initially, efficient comb generation at wavelengths as short as 265nm will be performed. Ultimately, designs that are directed to comb generation in the 220-240 emission band will be studied. 3. The UV generating microcomb described in item 2 above will be tested as a source in a dual comb spectroscopy system. 4. As a stretch goal, testing of the the dual micocomb system for CARS will be conducted.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 22, 2019
- Source ID
- W911NF1610548
Entities
People
- Kerry Vahala
Organizations
- Army Contracting Command
- California Institute of Technology
- Defense Advanced Research Projects Agency