Optoelectronics Today and its Prospects

Elements, units, devices and systems in which at least one transition of photons to electrons or vice versa is used are referred to as optoelectronics. Some of optoelectronic elements are sensors (photo-receivers in the range from photo-resistors to photo-multipliers) of all types that add spectral ranges from X-Rays through IR radiation and have a sensitivity in the range from the order of 10 in -14 W VHz to the values that make it possible to count separate photons.

There can be discrete sensors (single elements) or multi-element rules and matrices. For example, there are CCD rules and matrices that contain several tens through several tens thousand elements per a line.

Some of optoelectronic elements are radiators that transform electrons into photons. This class includes all types of lamps, photo-diodes and lasers.

Photo-diodes add spectral ranges of all visible light and, partly, near IR range. They radiate power in the range from several mW to tens W. They are also produced as discrete elements or as rules and matrices.

Lasers (coherent radiators) can be of solid, fluid, gas, and semiconductor types. They add spectral ranges from ultraviolet to IR radiation and radiate the power in the range from several mW to tens kW. High-power lasers are used first of all in the material processing technology.

Functional optoelectronic units are first of all the opto-couplers that can transform electrons into photons or vice versa. A wide range of opto-couplers is manufactured. They work mainly in the IR spectral range and are targeted to be used in reading or detecting devices and for decoupling in the electro-plating .

1. The mentioned elements and parts are widely used in optical communication lines that are in progress during the last twenty years. Up-to-the-date communication lines are featured by the attenuation 0.5 to 0.7 dB/km. Multi-fiber cables are also used. The equipment is manufactured for the connection of separate fibers: special connectors, arc welding, etc. Fiber communication lines are as long as several thousand km. In Germany the phone line users can have through five lines per a flat due to the application of fiber communication lines. In Japan there are very cheap cellular phones that use IR communication channels enabling communication even from the subway.
   
2. There are optoelectronic measuring systems based on optoelectronic sensors (triangulation, reflecting, etc. ) targeted to define 3D object sizes. In 3D systems various optoelectronic scanners are used, including CCD rules and matrices, polygon mirror scanners, etc., thus providing both a micron precision and a higher speed of response. Nano-technology systems are known (con-focal microscopes, etc.) that provide a nanometer precision.
   
3. Indication (screens, displays) and registering systems. Liquid crystal displays (LCD) and plasma (gas-discharge) panels represent indication systems. The so-called E-paper (test pieces are brought to the market) is of a great interest.. It is based on electrically controlled micro-blinkers (micro balls filled with a white or black color). A new class of indication systems may be built based on the rules and matrices of the electrically controlled micro-mirrors. They enable development of large screens brighter than CCD-projection screens with a higher resolution. Widespread are laser printers. Until now they are rather expensive (especially the color ones).
   
4. Laser rangers are widespread in geodesy and in the space technology. They enable definition of a distance of thousands km with a several mm error.
   
   Optoelectronic units are used practically in all fields of technology, medicine, agriculture, transport, defense, power.
   
   The progress of this field is connected with several new possibilities. Nonlinear optics, including fiber optics enables various nonlinear (for example, spectral) transformations. The conventional macro-optics is changed for the micro-optics. A technology of manufacturing complex optoelectronic systems based on a single chip similar to the electronic micro-chips has been developed.
   
   In general, the micro-optics integrated with the micro-electronics provides a sort of technical revolution similar to the revolution caused by the integral electronics. The author believes that the conventional connectors in such complex systems as computers will be soon replaced by non-contact optoelectronic connectors, external and internal wiring not being mainly needed. Thus, the systems will become much more reliable.
   
   A new generation of computers will be optic-based computers. They are being developed several years, and they will provide a higher speed of response, a higher word length, a holographic memory, a higher reliability. Optoelectronic transformations will become much more efficient, thus solar suppliers and other optoelectronic transformers will be used wider. Very simple highly reliable remote-action optoelectronic protection systems will be used in the defense.
   
   The review is based on the Internet information.