Microresonator solitons orbit around a closed waveguide path and produce a repetitive output pulse stream at a rate set by the roundtrip time. Here, counter-propagating solitons that simultaneously orbit in an opposing sense (clockwise/counter-clockwise) are studied. Despite sharing the same spatial mode family, their roundtrip times can be precisely and independently controlled. Furthermore, a state is possible in which their relative optical phase and repetition rates are locked. This state allows a single resonator to produce dual-soliton frequency-comb streams with different repetition rates, but with a high relative coherence that is useful in spectroscopy and ranging.
Dissipative Kerr soliton mode locking in high-Q silica micro cavities is reviewed including resonator dispersion optimization. Phenomena relating to soliton propagation in the micro cavity are studied including dispersive wave generation and soliton trapping. Applications of the soliton comb are described.
We report the demonstration of strong coupling between single Cesium atoms and a high-Q chip-based microresonator.
Our toroidal microresonators are compact, Si chip-based whispering gallery mode resonators that confine light to small
volumes with extremely low losses, and are manufactured in large numbers by standard lithographic techniques.
Combined with the capability to couple efficiently light to and from these microresonators by a tapered optical fiber,
toroidal microresonators offer a promising avenue towards scalable quantum networks. Experimentally, laser cooled Cs
atoms are dropped onto a toroidal microresonator while a probe beam is critically coupled to the cavity mode. When an
atom interacts with the cavity, it modifies the resonance spectrum of the cavity, leading to rejection of some of the probe
light from the cavity, and thus to an increase in the output power. By observing such transit events while systematically
detuning the cavity from the atomic resonance, we determine the maximal accessible single-photon Rabi frequency of
Ω0/2π ≈ (100 ± 24) MHz. This value puts our system in the regime of strong coupling, being significantly larger than the dissipation rates in our system.
We describe the performance of submicron microdisk and photonic crystal lasers fabricated within InGaP/InGaAlP
quantum well material. The smallest lasers, with diameters of approximately 600 nm, feature ultra-small mode volumes
and exhibit single mode operation at low threshold powers. Their small cavity volumes of approximately 0.03 μm3 for
microdisk lasers and 0.01 μm3 for photonic crystal lasers enable them to be used as spectroscopic sources. Here we
demonstrate the fabrication and characterization of visible, monolithically fabricated, submicron mode volume lasers.
Recently, a method for fabricating planar arrays of optical microtoroid resonators with quality factors greater than 500 million was developed. These devices have previously demonstrated Raman and OPO lasing and radiation pressure induced oscillations. When immersed in an aqueous environment, these devices are able to maintain their ultra-high Q factors by operating in the visible wavelength band, enabling very sensitive chemical and biological detection. The fabrication and optical properties of these devices will be described. These devices have performed both chemical and biological detection. Systems which have been detected include D2O in water and a variety of biological molecules. Sensitivity limits will also be discussed.
Nondegenerate four-wave mixing in semiconductor optical amplifiers was studied both as a spectroscopic tool for probing semiconductor dynamics and as a wavelength conversion technique. Four-wave mixing spectra were measured at detuning frequencies ranging from GHz to THz rates and ultrasfast intraband mechanisms having relaxation time constants of 650 fs and less than 100 fs were revealed in the measurements. Cross-polarization four-wave mixing was also measured to study the inter quantum-well carrier transport process in quantum-well amplifiers. In addition, broadband wavelength conversion using four-wave mixing in semiconductor optical amplifiers was investigated. Results concerning the conversion efficiency over spans up to 65 nm, as well as a demonstration of wavelength conversion with gain are presented. The issue of converted signal-to-background noise in this process is also addressed.
We have demonstrated selective epitaxial growth of A1Gai_As, with an abrupt transition in the bandgap lateral
to the growth direction. Spontaneous compositional modulation, with an associated reduction in the effective
bandgap, occurs in AlGaAs grown by molecular beam epitaxy on the sides of grooves in a GaAs substrate. The
bandgap is observed to be dependent on the groove orientation. Possible mechanisms for the orientation dependent
growth are discussed.
There is currently great interest in fabrication of structures that are two and three
dimensional analogs of the conventional quantum well. We review here the physics behind
the use of arrays of such lower dimensional structures in semiconductor laser active layers.
Methods which are currently under investigation for producing such structures will be