A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength–thick waveguide for vertical confinement and a two-dimensional photonic crystal mirror for lateral localization. A defect in the photonic crystal is introduced to trap photons inside a volume of 2.5 cubic half-wavelengths, approximately 0.03 cubic micrometers. The laser is fabricated in the indium gallium arsenic phosphide material system, and optical gain is provided by strained quantum wells designed for a peak emission wavelength of 1.55 micrometers at room temperature. Pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.

https://science.sciencemag.org/content/sci/284/5421/1819.full.pdf

Two-Dimensional Photonic Band-Gap Defect Mode Laser

Organic semiconductor lasers.

An imaging system for a vehicle includes an imaging device having a field of view exteriorly and forward of the vehicle in its direction of travel, and an image processor operable to process the captured images in accordance with an algorithm. The algorithm comprises a sign recognition routine and a character recognition routine. The image processor processes the image data captured by the imaging device to detect signs in the field of view of the imaging device and applies the sign recognition routine to determine a sign type of the detected sign. The image processor is operable to apply the character recognition routine to the image data to determine information on the detected sign. The image processor applies the character recognition routine to the captured images in response to an output of the sign recognition routine being indicative of the detected sign being a sign type of interest.

Imaging system for vehicle

A rearview vision system (12) for a vehicle includes at least one image capture device (16) directed rearwardly with respect to the direction of travel of the vehicle. A display system (20) displays an image synthesized from output of the image capture device. The display system is preferably contiguous with the forward field of view of the vehicle driver at a focal length that is forward of the vehicle passenger compartment. A plurality of image capture devices (14, 16) may be provided and the display system displays a unitary image synthesized from outputs of the image capture devices which approximates a rearward-facing view from a single location, such as forward of the vehicle.

Rearview vision system for vehicle including panoramic view

A personal digital assistant (PDA) (10) stores data from physiological monitors (12) so that the data can be used in various software applications. In different embodiments the physiological monitor (12) can include data storage or have memory modules that are accepted by accessory slots (48 and 50).

Physiological monitor and associated computation, display and communication unit

2128539 9314520 PCTABScor01 Optoelectronic integrated circuits (110) are disclosed comprising a vertical-cavity surface emitting laser (VCSEL) (118) and a transistor (116). The VCSEL comprises a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers (142, 144) surrounding one or more active, optically emitting quantum-well layers (3) having a bandgap in the visible range which serves as the active optically emitting material of the device. The thickness of the laser cavity is m.lambda./2neff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and neff is the effective index of refraction of the cavity. Electrical pumping of the laser (118) is achieved by heavily doping the bottom mirror (145) and substrate to one conductivity-type and heavily doping the regions of the upper mirror (141) with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Embodiments are disclosed which integrate the VCSEL (118) with bipolar (126, 136) and FET (316) transistors as well as phototransistors (416).

Integration of transistors with vertical cavity surface emitting lasers

We report batch-processed, totally planar, vertical-cavity top surface emitting GaAs/AlGaAs laser devices and arrays. Different size devices are studied experimentally. We measure continuous-wave threshold currents down to 1.7 mA and output powers > 3.7 mW at room temperature. We also discuss interesting characteristics such as differential quantum efficiencies exceeding unity and multi-transverse mode behavior. An array having 64 X 1 individually-accessed elements is characterized and shown to have uniform room-temperature continuous-wave operating characteristics in threshold current approximately equals 2.1 +/- 0.1 mA, wavelength approximately equals 849.4 +/- 0.8 nm, and output power approximately equals 0.5 +/- 0.1 mW.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Progress in planarized vertical cavity surface emitting laser devices and arrays

A new class of cascadable optical logic devices is described which consists of integrated GaAs/AlGaAs phototransistors and surface-emitting lasers. The devices function as optical neurons (‘smart pixels’), have high optical gain (a factor of >20 overall, >200 differential), very high on/off contrast (>2700, 34dB) and are ideal for neural networks and optical computing applications.

Cascadable laser logic devices: discrete integration of phototransistors with surface-emitting laser diodes

A novel and simple scheme used to achieve a 2-D array of monolithic multiple wavelength lasers is reported. Uniformly separated wavelengths are emitted from an eight-element linear array and an 8 × 8 2-D array of surface emitting lasers in the 950 nm regime. The lasers all have nearly identical light against current characteristics.

Surface emitting laser arrays with uniformly separated wavelengths

A phased array of semiconductor laser elements is provided in which the percentage of light which propagates into different diffractive orders is modified by an optical element. The diode laser includes a body of a semiconductor material having an active region therein which is adapted to generate radiation and emit the radiation form a surface of the body, and separate reflecting mirrors at opposite sides of the active region with at least one of the mirrors being partially transparent to the generated light to allow the light generated in the active region to be emitted therethrough. The optical element may take the form of a modification in the arrangement of the semiconductor laser elements, or an array of microprisms, or an external mirror to modify the percentage of light which propagates into different diffractive orders.

Jack L. Jewell

Papers

Integration of transistors with vertical cavity surface emitting lasers

Progress in planarized vertical cavity surface emitting laser devices and arrays

Cascadable laser logic devices: discrete integration of phototransistors with surface-emitting laser diodes

Surface emitting laser arrays with uniformly separated wavelengths

Phased array semiconductor laser