Abstract: A disk resonator is pumped by counterpropagating pump signals to produce corresponding counterpropagating Brillouin laser signals. The pump laser optical frequencies are separated by a frequency offset ??P but excite the same nominal resonator optical mode; the Brillouin laser optical frequencies are separated by a beat frequency ??L with 0<??L<??P. A photodetector receives the Brillouin laser signals and produces an electrical signal at the beat frequency ??L. The frequency offset ??P can be large so enough to prevent locking of the Brillouin laser signals onto a common Brillouin laser frequency. A signal processing system derives from the beat frequency ??L an estimated angular velocity component of the disk optical resonator about an axis substantially perpendicular to the disk optical resonator.

Abstract: A disk resonator is pumped by counterpropagating pump signals to produce corresponding counterpropagating Brillouin laser signals. The pump laser optical frequencies are separated by a frequency offset ??P but excite the same nominal resonator optical mode; the Brillouin laser optical frequencies are separated by a beat frequency ??L with 0<??L<??P. A photodetector receives the Brillouin laser signals and produces an electrical signal at the beat frequency ??L. The frequency offset ??P can be large so enough to prevent locking of the Brillouin laser signals onto a common Brillouin laser frequency. A signal processing system derives from the beat frequency ??L an estimated angular velocity component of the disk optical resonator about an axis substantially perpendicular to the disk optical resonator.

Abstract: An optical apparatus comprises a waveguide substrate and an optical reference cavity. The optical reference cavity comprises an optical waveguide formed on the waveguide substrate and arranged to form a closed loop greater than or about equal to 10 cm in length. The RMS resonance frequency fluctuation is less than or about equal to 100 Hz. The Q-factor can be greater than or about equal to 108. The optical waveguide can exhibit optical loss less than or about equal to 0.2 dB/m for propagation of an optical signal along the optical waveguide. The closed loop path can comprise two or more linked spirals greater than or about equal to 1 meter in length and can occupy an area on the waveguide substrate less than or about equal to 5 cm2.

Abstract: A substrate includes a semiconductor layer, a plurality of dielectric layers disposed on one side of the semiconductor layer and separated from each other and a photoactive layer disposed between the dielectric layers and including a compound of a Group III element and a Group V element. Also disclosed are a solar cell including the same and a manufacturing method thereof.

Abstract: According to example embodiments, a solar cell includes a photovoltaic layer, a plurality of front electrodes, a rear electrode, and a transparent subsidiary electrode. The plurality of front electrodes and the rear electrode are disposed respectively on front and rear surfaces of the photovoltaic layer. The subsidiary electrode is disposed on front surfaces of the photovoltaic layer and the front electrodes. The subsidiary electrode may be graphene.

Abstract: A solar cell includes a base layer; an emitter layer disposed on one side of the base layer; a first electrode in electrical communication with the base layer; and a second electrode in electrical communication with the emitter layer, wherein the base layer has a higher doping concentration with increasing distance from the interface between the base layer and the emitter layer, and the base layer has a doping concentration change slope that is further decreased with increasing distance from the interface between the base layer and the emitter layer.

Abstract: A substrate includes a semiconductor layer, a plurality of dielectric layers disposed on one side of the semiconductor layer and separated from each other and a photoactive layer disposed between the dielectric layers and including a compound of a Group III element and a Group V element. Also disclosed are a solar cell including the same and a manufacturing method thereof.

Abstract: A solar cell includes a base layer; an emitter layer disposed on one side of the base layer; a first electrode in electrical communication with the base layer; and a second electrode in electrical communication with the emitter layer, wherein the base layer has a higher doping concentration with increasing distance from the interface between the base layer and the emitter layer, and the base layer has a doping concentration change slope that is further decreased with increasing distance from the interface between the base layer and the emitter layer.

Abstract: A solar concentrator comprises an incidence surface, a first reflective curved surface corresponding to the incidence surface, a second reflective curved surface disposed in a center part of the incidence surface, and a concentrating part disposed in a center part of the first reflective curved surface and corresponding to the second reflective curved surface, wherein the incidence surface, the first reflective curved surface, the second reflective curved surface, and the concentrator include a substantially same material from each other.

Abstract: Provided is a vertical light emitting device having improved light extraction efficiency and a method of manufacturing the same. The vertical light emitting device may include a p type electrode, a p type semiconductor layer, an active layer, and an n type semiconductor layer which may be sequentially formed on the p type electrode, and an n type electrode on a portion of a surface of the n type semiconductor layer, wherein the portion of the surface of the n type semiconductor layer may be at an inclined plane inclined from an area near a circumference of the n type electrode towards the active layer. The p type electrode may include a current blocking layer which is made of an insulating material and on the p type electrode directly under the n type electrode. Accordingly, a voltage increase may be minimized or reduced, and light extraction efficiency may be improved.