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

A solid-state scanner for reading bar codes or projecting images is described. The scanner operates either in a reading mode or a calibrate mode using the same hardware. Use of two-dimensional array light sources minimizes the size of the semiconductor chips containing the light source arrays is provided. Use of oversampling or anamorphic optical systems increase tolerances to angular misorientations is also discussed. Used in conjunction with a mechanical scanning device, the scanner is capable of reading two-dimensional bar codes or generating two-dimensional images.

Self calibrating solid state scanner

A compact and ultrafast holographic memory using a recently developed surface-emitting microlaser diode array is described. The system does not require a bulky laser, spatial light modulators, or beam deflectors. The memory is capable of retrieving a high-resolution page (approximately 105 bits) in less than 1 nsec.

Compact and ultrafast holographic memory using a surface-emitting microlaser diode array.

Highly efficient (1.2 mW/mA, >70% CW differential quantum efficiency), top-surface-emitting, vertical cavity lasers are achieved at room temperature. Buried damage layers by proton implantation are used for efficient current funnelling. The CW threshold currents are 3.5–8.0 mA, at 3.7–4.2 V bias, for 10.30 μm diameter lasers. The lasing wavelengths are 845–848 nm.

High efficiency (1.2 mW/mA) top-surface-emitting GaAs quantum well lasers

Monolithic optical logic devices 1.5-5 μm across are defined by ion-beam assisted etching through a GaAs/AlAs Fabry-Perot structure grown by molecular beam epitaxy. They show reduced energy requirements (factor 30 smaller than the unetched heterostructure), uniform response over small arrays, negligible crosstalk at 3-μm center-center spacing, <200 ps recovery time and thermal stability at 82 MHz operating frequency. All experiments were performed at room temperature.

GaAs-AlAs Monolithic Microresonator Arrays

We fabricated low threshold In0.2Ga0.8As surface emitting microlasers having various etch depths and sizes. Comparison of electrical and optical properties was made between deep etched (deeper than the active layer) and shallow etched (shallower than the active layer) microlasers. Shallow etched microlasers were F-ion implanted to limit current spreading. The ion implanted shallow etched samples, when larger than about 5 µm across, show improved room temperature CW characteristics with lower resistances and lower operating voltages than the deep etched microlasers.

Jack L. Jewell

Papers

Self calibrating solid state scanner

Compact and ultrafast holographic memory using a surface-emitting microlaser diode array.

High efficiency (1.2 mW/mA) top-surface-emitting GaAs quantum well lasers

GaAs-AlAs Monolithic Microresonator Arrays

Effects of etch depth and ion implantation on surface emitting microlasers