A micro-ring resonator includes: at least one first straight waveguide; a second waveguide (Arm3) and a third waveguide (Arm2), where the second waveguide (Arm3) and the third waveguide (Arm2) form a closed annular waveguide, and the annular waveguide is coupled to the first waveguide; a fourth waveguide (Arm1), where the fourth waveguide (Arm1) is coupled to the annular waveguide; and a polarization splitter (PS), where one end of the polarization splitter (PS) is connected to the fourth waveguide (Arm1), and one end is connected to the second waveguide (Arm3) in the annular waveguide. In the micro-ring resonator, a distance between two waveguides for separately transmitting different polarized light breaks a limitation of a resonator radius, and further, a distance between a TE path and a TM path is reduced.

A device includes a substrate, a pedestal extending from the substrate, and a ring resonator disposed on the pedestal above the substrate. The ring resonator has a resonance wavelength greater than 1.5 μm and includes at least one of silicon and chalcogenide glass. The device can be used as a ring resonator sensor or a light source. The ring resonator is substantially transparent to mid-infrared radiation to reduce optical losses. The pedestal has a narrower width compared to the ring resonator to generate improved interaction between evanescent fields of light in the ring resonator and analytes nearby the ring resonator, thereby increasing sensing sensitivity. In addition, fabrication of the device is compatible with complementary metal-oxide-semiconductor (CMOS) processes and hence is amenable to large scale manufacturing.

Electro-optic devices for classical and quantum microwave photonics are provided. In various embodiments, a device comprises: a waveguide; a first ring resonator; a second ring resonator, the second ring resonator evanescently coupled to the first ring resonator and to the waveguide; a first pair of electrodes, one of the first pair of electrodes disposed within the first ring resonator and the other of the first pair of electrodes disposed without the first ring resonator; a second pair of electrodes, one of the second pair of electrodes disposed within the second ring resonator and the other of the second pair of electrodes disposed without the second ring resonator; a microwave source electrically coupled to the first and second pairs of electrodes; a bias port electrically coupled to the first and second pairs of electrodes and configured to sweep a frequency band.

A thermometer includes a substrate; an optical resonator disposed on the substrate and including an optical resonance, the optical resonator being configured to receive a resonant frequency corresponding to the optical resonance; and a waveguide disposed on the substrate proximate to the optical resonator to receive input light, to communicate the resonant frequency to the optical resonator, and to transmit output light; wherein an aperture is interposed between: the substrate and the optical resonator, the substrate and the waveguide, or a combination comprising at least one of the foregoing, and the thermometer is configured to change the optical resonance in response to a change in temperature of the optical resonator.

A photodetector includes a germanium layer evanescently coupled to a ring resonator. The ring resonator increases the interaction length between light guided by the ring resonator and the germanium layer without increasing the size of the photodetector, thereby keeping the photodetector's dark current at a low level. The germanium layer absorbs the guided light and converts the absorbed light into electrical signals for detection. The increased interaction length in the resonator allows efficient transfer of light from the resonator to the germanium layer via evanescently coupling. In addition, the internal and external quality factors (Q) of the ring resonator can be matched to achieve (nearly) full absorption of light in the germanium with high quantum efficiency.

According to an aspect, an optical system includes a laser diode configured to emit optical signals and at least two size-switchable broken racetrack ring resonators optically coupled to an optical waveguide, where each broken racetrack ring resonator is configured to exhibit a resonant wavelength. The optical system also includes a tuning arrangement associated with the broken racetrack ring resonators, where the tuning arrangement includes a micro electro-mechanical system (MEMS) or nano electro-mechanical system (NEMS) actuator mechanically coupled to a first portion of a first one of the broken racetrack ring resonators and configured to mechanically move the first portion so as to change the resonant wavelength of the first one of the broken racetrack ring resonators.

An electromagnetic wave resonator comprising a body, wherein the body: has a structure extending essentially in a plane (r, θ), comprises a material in a region between limit radii r.sub.i and r.sub.o, where 0≦r.sub.i<r.sub.o and r.sub.o corresponds to a radius of a convex hull () of the structure; and allows for electromagnetic wave propagation, and wherein an effective refractive index n.sub.e(r), as obtained from angularly averaging a refractive index of the material in the plane (r, θ), decreases within said region.

An add-drop filter for transmitting at least one signal is provided. The add-drop filter includes at least two optical waveguides capable of carrying the at least one signal, and at least one active resonator coupled between the optical waveguides, wherein the at least one active resonator provides gain that counteracts losses for the at least one signal.

A device and method for post-fabrication trimming of an optical ring resonator using a dopant-based heater is provided. An optical ring resonator at the device can be heated using heaters in an optical slab from which the optical ring resonator extends, the heater including a non-uniform doping profile. A controller determines an initial resonance frequency and a target resonance frequency of the optical ring resonator. The controller applies predetermined electrical parameters to the heater using electrical connections to shift a resonance frequency of the optical ring resonator from the initial resonance frequency to the target resonance frequency by causing the dopant in the heater to migrate.

Apparatus, sensor chips and techniques for optical sensing of substances by using optical sensors on sensor chips.