46 research outputs found
Dynamic release of trapped light from an ultrahigh-Q nanocavity via adiabatic frequency tuning
Adiabatic frequency shifting is demonstrated by tuning an ultrahigh-Q
photonic crystal nanocavity dynamically. By resolving the output temporally and
spectrally, we showed that the frequency of the light in the cavity follows the
cavity resonance shift and remains in a single mode throughout the process.
This confirmed unambiguously that the frequency shift results from the
adiabatic tuning. We have employed this process to achieve the dynamic release
of a trapped light from an ultrahigh-Q cavity and thus generate a short pulse.
This approach provides a simple way of tuning Q dynamically.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
High-Q coupled resonances on a PhC waveguide using a tapered nanofiber with high coupling efficiency
We experimentally demonstrate high-Q cavity formation at an arbitrary
position on a silicon photonic crystal waveguide by bringing a tapered
nanofiber into contact with the surface of the slab. An ultrahigh Q of 5.1 x
10^5 is obtained with a coupling efficiency of 39%, whose resonant wavelength
can be finely tuned by 27 pm by adjusting the contact length of the nanofiber.
We also demonstrate an extremely high coupling efficiency of 99.6% with a
loaded Q of 6.1 x 10^3. In addition, we show that we can obtain an all-pass
filter type coupled resonator system, which has the potential to be used for
slow light generation.Comment: 8 pages, 7 figures. The following article has been submitted to
Optics Express. After it is published, it will be found at
https://www.osapublishing.org/oe/home.cf
Polygonal silica toroidal microcavity for controlled optical coupling
We fabricated polygonal silica toroidal microcavities to achieve stable
mechanical coupling with an evanescent coupler such as a tapered fiber. The
polygonal cavity was fabricated by using a combination of isotropic etching,
anisotropic etching and laser reflow. It offers both high and low coupling
efficiencies with the cavity mode even when the coupler is in contact with the
cavity, which offers the possibility of taking the device outside the
laboratory. A numerical simulation showed that an octagonal silica toroidal
microcavity had an optical quality factor of 8.8\times10^6.Comment: 13 pages, 4 figure
Mechanically actuated Kerr soliton microcombs
Mode-locked ultrashort pulse sources with a repetition rate of up to several
tens of gigahertz greatly facilitate versatile photonic applications such as
frequency synthesis, metrology, radar, and optical communications. Dissipative
Kerr soliton microcombs provide an attractive solution as a broadband,
high-repetition-rate compact laser system in this context. However, its
operation usually requires sophisticated pump laser control to initiate and
stabilize the soliton microcombs, particularly in millimeter-sized ultrahigh-Q
whispering-gallery resonators. Here, we realize a mechanically actuated soliton
microcomb oscillator with a microwave repetition rate of 15 GHz. This enables
direct soliton initiation, long-term stabilization, and fine tuning, where the
operation now lifts the prerequisite pump laser tunability that must be relaxed
if the technology is to be widely used outside the laboratory environment. We
reveal the prospects for using this method with a wide range of applications
that would benefit from mechanical soliton actuation such as optical clocks,
spectral extension, and dual-comb spectroscopy