Abstract: A safety device and method for stairs, escalators and moving sidewalks that moves a person sitting or sliding on a handrail onto the steps to avoid accidents. The safety device includes a sloped surface that can be part of an elongated pyramid. The sloped surface is at an angle of between about 30° and about 45° from the direction of the handrail, with 45° being preferred. The safety device is free of sharp edges and is configured to avoid catching on a person's clothing. The safety device may include illumination.

Abstract: The present invention provides an improved optoelectronic device and a method of manufacture therefor. The optoelectronic device includes a doped buffer layer located over a substrate having an optical window formed therein and an absorber layer located over the doped buffer layer. The optoelectronic device further includes a doped region located over the absorber layer and having a dopant tail that extends substantially through the absorber layer, and the doped buffer layer and the dopant tail are doped to augment an optical power threshold for bandwidth collapse of the optoelectronic device.

Abstract: An advantageous method of fabricating lasers adapted for use in a multichannel analog optical fiber communication system, e.g., a CATV system, is disclosed. A laser generally can be used in such a communication system only if it meets, inter alia, very stringent intermodulation specifications. To identify such lasers typically requires extensive testing. It has now been discovered that certain readily determinable parameters can be used to predict the intermodulation behavior of a given device. This discovery makes possible a simpler, and therefore less costly, process of identifying suitable lasers, resulting in a more economical method of making lasers for the stated application. The method comprises measuring the light versus current (L versus I) characteristic of a given laser, determining therefrom the first, second, and possibly higher, order derivatives of L with respect to I, and determining thereform a parameter that is a predictor of the distortion behavior of the laser.

Abstract: An amplitude-modulated vestigial-sideband, television channel sub-carrier multiplexed optical fiber transmission system includes a laser diode operating linearly throughout the desired range of multiplex frequencies. Such linear laser diode operation is accomplished by limiting leakage current within the laser diode to a very low level. The composite second-order distortion in the optical output signal from the laser diode is down typically 50 db from the video carrier for each channel. For some laser diodes that exhibit slow turn-on in the L-I characteristic, there is a point of inflection in the L-I curve. Operation with the laser biased at or near this point results in extremely linear performance, even though the laser may have insufficient blocking of leakage current to otherwise produce acceptable linearity.

Abstract: Lasers for use in multichannel analog optical fiber communication systems (e.g., of the type contemplated for CATV) have to meet very stringent requirements, including high linearity. DFB lasers are advantageously used in such communication systems. Typically only a relatively small percentage of the nominally identical DFB lasers on a wafer meet the specifications. It has now been discovered that the likelihood that a given DFB laser will meet the requirements is substantially increased if the laser comprises means that are adapted for producing a non-uniform photon density in the laser cavity, with the density of photons being larger in the rear portion of the cavity than in the front portion, such that during operation of the laser the gain in the back portion is substantially independent of the laser current, whereas the gain in the front portion is a function of the laser current. Exemplarily, lasers according to the invention have power asymmetry less than about 5.