Visible Kerr comb generation in a high-Q silica microdisk resonator with a large wedge angle

This paper describes the specially designed geometry of a dry-etched large-wedge-angle silica microdisk resonator that enables anomalous dispersion in the 780 nm wavelength regime. This anomalous dispersion occurs naturally without the use of a mode-hybridization technique to control the geometrical dispersion. By fabricating a1-μm-thick silica microdisk with a wedge angle as large as 56° and an optical Q-factor larger than 107, we achieve a visible Kerr comb that covers the wavelength interval of 700–897 nm. The wide optical frequency range and the closeness to the clock transition at 698 nm of 87 Sr atoms make our visible comb a potentially useful tool in optical atomic clock applications.

Mid-infrared chalcogenide microfiber knot resonators

A novel type of mid-IR microresonator,the chalcogenide glass(ChG)microfiber knot resonator(MKR),is demonstrated,showing easy fabrication,fiber-compatible features,resonance tunability,and high robustness.ChG micro fibers with typical diameters around 3μm are taper-drawn from As2S3 glass fibers and assembled into MKRs in liquid without surface damage.The measured Q factor of a typical 824μm diameter ChG MKR is about 2.84×104 at the wavelength of 4469.14 nm.The free spectral range(FSR)of the MKR can be tuned from2.0 nm(28.4 GHz)to 9.6 nm(135.9 GHz)by tightening the knot structure in liquid.Benefitting from the high thermal expansion coefficient of As2S3 glass,the MKR exhibits a thermal tuning rate of 110 pm·℃^-1 at the resonance peak.When embedded in polymethyl methacrylate(PMMA)film,a 551μm diameter MKR retains a Q factor of 1.1×10^4.The ChG MKRs demonstrated here are highly promising for resonator-based optical technologies and applications in the mid-IR spectral range.

High-Q silica microdisk optical resonators with large wedge angles on a silicon chip

We experimentally demonstrate high optical quality factor silica microdisk resonators on a silicon chip with large wedge angles by reactive ion etching. For 2-μm-thick microresonators, we have achieved wedge angles of 59°, 63°,70°, and 79° with optical quality factors of 2.4 × 10~7, 8.1 × 10~6, 5.9 × 10~6, and 7.4 × 10~6, respectively, from ～80 μm diameter microresonators in the 1550 nm wavelength band. Also, for 1-μm-thick microresonators, we have obtained an optical quality factor of 7.3 × 10~6 with a wedge angle of 74°.

Dry-etched ultrahigh-Q silica microdisk resonators on a silicon chip

We demonstrate the fabrication of ultrahigh quality(Q) factor silica microdisk resonators on a silicon chip by inductively coupled plasma(ICP) etching. We achieve a dry-etched optical microresonator with an intrinsic Q factor as high as 1.94×10^(8) from a 1-mm-diameter silica microdisk with a thickness of 4 μm. Our work provides a chip-based microresonator platform operating in the ultrahigh-Q region that will be useful in nonlinear photonics such as Brillouin lasers and Kerr microcombs.

Kerr frequency combs in large-size,ultra-high-Q toroid microcavities with low repetition rates [Invited]

By overcoming fabrication limitations, we have successfully fabricated silica toroid microcavities with both large diameter(of 1.88 mm) and ultra-high-Q factor(of 3.3 × 10~8) for the first time, to the best of our knowledge. By employing these resonators, we have further demonstrated low-threshold Kerr frequency combs on a silicon chip,which allow us to obtain a repetition rate as low as 36 GHz. Such a low repetition rate frequency comb can now bedirectly measured through a commercialized optical-electronic detector.

Demonstration of an ultra-low-threshold phonon laser with coupled microtoroid resonators in vacuum

We demonstrate an ultra-low-threshold phonon laser using a coupled-microtoroid-cavity system by introducing a novel coupling approach.The scheme exhibits both high optical quality factors and high mechanical quality factors.We have experimentally obtained the mechanical quality factor up to 18,000 in vacuum for a radialbreathing mode of 59.2 MHz.The measured phonon lasing threshold is as low as 1.2μW,which is～5 times lower than the previous result.