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Frequency combs with mode spacing of 10–20 GHz are critical for increasingly important applications such as astronomical spectrograph calibration, high-speed dual-comb spectroscopy, and low-noise microwave generation. While electro-optic modulators and microresonators can provide narrowband comb sources at this repetition rate, a significant remaining challenge is a means to produce pulses with sufficient peak power to initiate nonlinear supercontinuum generation spanning hundreds of terahertz (THz) as required for self-referencing. Here, we provide a simple, robust, and universal solution to this problem using off-the-shelf polarization-maintaining amplification and nonlinear fiber components. This fiber-integrated approach for nonlinear temporal compression and supercontinuum generation is demonstrated with a resonant electro-optic frequency comb at 1550 nm. We show how to readily achieve pulses shorter than 60 fs at a repetition rate of 20 GHz. The same technique can be applied to picosecond pulses at 10 GHz to demonstrate temporal compression by 9× and achieve 50 fs pulses with a peak power of 5.5 kW. These compressed pulses enable flat supercontinuum generation spanning more than 600 nm after propagation through multi-segment dispersion-tailored anomalous-dispersion highly nonlinear fibers or tantala waveguides. The same 10 GHz source can readily achieve an octave-spanning spectrum for self-referencing in dispersion-engineered silicon nitride waveguides. This simple all-fiber approach to nonlinear spectral broadening fills a critical gap for transforming any narrowband 10–20 GHz frequency comb into a broadband spectrum for a wide range of applications that benefit from the high pulse rate and require access to the individual comb modes.
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Double-Ridge Five Port Power Splitter Using Gap-Waveguide
In microwave engineering, waveguides are a key component when transmitting high frequency waves with low losses. However, these are inherently bulky in size and difficult to integrate with other microwave components. Gap-Waveguides are a good solution for mm-wave frequencies since they are easier to integrate with other components and easier to fabricate since there is no need for a complete physical shield. This work uses gap-waveguide technology to develop a 4:1 power splitter network that can operate from 20 GHz to 40 GHz with very low losses and less than 2:1 VSWR.
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- Award ID(s):
- 2132229
- PAR ID:
- 10561041
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3503-6990-8
- Page Range / eLocation ID:
- 1473 to 1474
- Format(s):
- Medium: X
- Location:
- Firenze, Italy
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/AP-S/INC-USNC-URSI52054.2024.10686999
