3,643 research outputs found
High performance photonic microwave filters based on a 50GHz optical soliton crystal Kerr micro-comb
We demonstrate a photonic radio frequency (RF) transversal filter based on an
integrated optical micro-comb source featuring a record low free spectral range
of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high
number of taps, or wavelengths for the transversal filter results in
significantly increased performance including a QRF factor more than four times
higher than previous results. Further, by employing both positive and negative
taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using
Gaussian apodization, together with a tunable centre frequency covering the RF
spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically
adjustable filter shapes. Our experimental results match well with theory,
showing that our transversal filter is a competitive solution to implement
advanced adaptive RF filters with broad operational bandwidths, high frequency
selectivity, high reconfigurability, and potentially reduced cost and
footprint. This approach is promising for applications in modern radar and
communications systems.Comment: 19 pages, 12 figures, 107 reference
Designing coupled-resonator optical waveguide delay lines
We address the trade-offs among delay, loss, and bandwidth in the design of coupled-resonator optical waveguide (CROW) delay lines. We begin by showing the convergence of the transfer matrix, tight-binding, and time domain formalisms in the theoretical analysis of CROWs. From the analytical formalisms we obtain simple, analytical expressions for the achievable delay, loss, bandwidth, and a figure of merit to be used to compare delay line performance. We compare CROW delay lines composed of ring resonators, toroid resonators, Fabry-Perot resonators, and photonic crystal defect cavities based on recent experimental results reported in the literature
Emerging applications of integrated optical microcombs for analogue RF and microwave photonic signal processing
We review new applications of integrated microcombs in RF and microwave
photonic systems. We demonstrate a wide range of powerful functions including a
photonic intensity high order and fractional differentiators, optical true time
delays, advanced filters, RF channelizer and other functions, based on a Kerr
optical comb generated by a compact integrated microring resonator, or
microcomb. The microcomb is CMOS compatible and contains a large number of comb
lines, which can serve as a high performance multiwavelength source for the
transversal filter, thus greatly reduce the cost, size, and complexity of the
system. The operation principle of these functions is theoretically analyzed,
and experimental demonstrations are presented.Comment: 16 pages, 8 figures, 136 References. Photonics West 2018 invited
paper, expanded version. arXiv admin note: substantial text overlap with
arXiv:1710.00678, arXiv:1710.0861
Microwave and RF Applications for Micro-resonator based Frequency Combs
Photonic integrated circuits that exploit nonlinear optics in order to
generate and process signals all-optically have achieved performance far
superior to that possible electronically - particularly with respect to speed.
We review the recent achievements based in new CMOS-compatible platforms that
are better suited than SOI for nonlinear optics, focusing on radio frequency
(RF) and microwave based applications that exploit micro-resonator based
frequency combs. We highlight their potential as well as the challenges to
achieving practical solutions for many key applications. These material systems
have opened up many new capabilities such as on-chip optical frequency comb
generation and ultrafast optical pulse generation and measurement. We review
recent work on a photonic RF Hilbert transformer for broadband microwave
in-phase and quadrature-phase generation based on an integrated frequency
optical comb. The comb is generated using a nonlinear microring resonator based
on a CMOS compatible, high-index contrast, doped-silica glass platform. The
high quality and large frequency spacing of the comb enables filters with up to
20 taps, allowing us to demonstrate a quadrature filter with more than a
5-octave (3 dB) bandwidth and an almost uniform phase response.Comment: 10 pages, 6 figures, 68 references. arXiv admin note: substantial
text overlap with arXiv:1512.0174
Free ultra-high-Q microtoroid: a tool for designing photonic devices
We describe techniques that enable fabrication of a new class of photonic devices based on free UH-Q microresonators. Preliminary results show that free silica microtoroids with Qs above 30 million can be fabricated and transferred to different platforms for integration with a variety of photonic devices
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