Abstract: A process is described for making semiconductor lasers with cleaved facets for end mirrors. The process involves electrochemically photoetching slots with deep, narrow cross-sections in a wafer and applying stress to cleave the wafer in the desired place. Extremely short and reproducible semiconductor lasers can be made by this procedure (less than 50 or even 25 .mu.m) which yields extremely useful semiconductor lasers particularly for communication applications. Also, the procedure requires a minimum of skill to produce excellent quality cleaved semiconductor lasers (including short-length lasers) with high yields.

Abstract: A dual-wavelength light-emitting diode (10) is disclosed wherein at least two quaternary layers (102 and 104) are epitaxially grown on indium phosphide substrate (100) and a top indium phosphide layer (105) of the opposite conductivity type is grown to establish a junction (121) in the topmost quaternary layer. An isolation channel (106) cuts through the epitaxial layers and divides the device into two separate regions. A dopant is diffused into one of the regions in order to establish a pn junction (122) in the bottom quaternary layer. Independent electrical contacts (107 and 108) bonded to the top indium phosphide layer in each of the regions establish an electrical connection to pn junctions in each of the two separate regions. The device can be effectively heat sinked by mounting the epitaxial layer side of the substrate to a beryllium oxide heat sink (200) onto which gold bonding pads (201 and 202) have been plated.

Abstract: A 3-terminal totally integrated demultiplexing photodiode is disclosed wherein information present simultaneously at two wavelengths can be developed into two separate currents available at the three terminals. Two quaternary n-type layers (103 and 105) of indium gallium arsenide phosphide having unequal bandgaps and each having a pn junction are separated by a layer (104) of n-type indium phosphide. The device is oriented so as to present the incoming radiation first to the quaternary layer having the larger bandgap and then to the quaternary layer having the lower bandgap. One of the contacts (111) is attached to the top layer (106) of n-type indium phosphide, a second contact (112) is attached to a central p-type region (110) established in the top layer of indium phosphide and penetrating through the top quaternary layer, and the third contact (113 or 302) is connected either to the indium phosphide substrate (101) or to a p-type outer region (301) that surrounds all of the layers.

Abstract: A three terminal, totally integrated demultiplexing photodiode is disclosed wherein information present simultaneously at two wavelengths can be developed into two separate currents available at the three terminals. Two quaternary layers (203 and 205) of indium, gallium, arsenide phosphide having unequal bandgaps and each having a pn junction are separated by a buffer layer (204) of n type indium phosphide. Operation at longer wavelengths is achieved by causing the bottom quaternary layer to have the higher bandgap energy thereby permitting it to detect the shorter wavelengths in the radiation and causing the topmost quaternary layer (205) to have the lower bandgap energy thereby permitting it to detect the longer wavelengths. The bottom contact (213) on the substrate has an opening thereby providing a window (230) through which incoming radiation (250) can be coupled through the substrate to the two quaternary layers.

Abstract: A 3-terminal totally integrated demultiplexing photodiode is disclosed wherein information present simultaneously at two wavelengths can be developed into two separate currents available at the three terminals. Two quaternary n-type layers (103 and 105) of indium gallium arsenide phoshide having unequal bandgaps and each having a pn junction are separated by a layer of (104) of n-type indium phosphide. The device is oriented so as to present the incoming radiation first to the quaternary layer having the larger bandgap and then to the quaternary layer having the lower bandgap. One of the contacts (111) is attached to the top layer (106) of n-type indium phosphide, a second contact (112) is attached to a central p-type region (110) established in the top layer of indium phosphide and penetrating through to the top quaternary layer, and the third contact (113 or 302) is connected either to the indium phosphide substrate (101) or to a p-type outer region (301) that surrounds all of the layers.

Abstract: A light-activated light-emitting device has at least one p-n junction provided with electrodes for confining light-emission to an area of the junction. It has been determined that light-emission can be activated by light impinging on the junction outside this confined area, so two optical fibers are provided, one being an input fiber for bringing activating light to the nonemitting sensitive part of the junction and the other fiber being an output fiber coupled to the light-emitting area. When the device is a p-n-p-n light-activated light-emitting switch provided with an RCL reset control circuit, a very inexpensive unidirectional optical pulse regenerator is obtained. The device in its various forms is advantageously suited for use in each of many stations along optical fiber data busses or in optical logic arrays because the unidirectional feature prevents light feedback between adjacent devices and consequently avoids spurious switching of a preceding device.