Patent GB-1309701-A (GB)
Title: Optical-electronic solid-state systems
IPC: G02F1/00
Filed: 1970-04-01
Abstract: 1309701 Optical-electronic solid state device SIEMENS AG 1 April 1970 [3 April 1969] 15353/70 Heading G2J [Also in Division H1] An integrated optical-electronic solid state system comprises a semi-conductor crystal indicated by the surfaces 31 and 301, the region 31 being the higher, and an optical conductor plate located on the lower region 301 and consisting of the parts 32, 321, 322, 323, 324 and 36, which are assembled in intimate contact. The part 36 is a double-refracting optically non-linear anistropic crystal chip, for example of potassium dihydrogen phosphate (KDP), while the other parts are of glass or other optically transmissive material and have ground side faces. Inputs to the system are two light sources 34 and 341, for example laser elements of stimulable glass or laser crystals excited by an additional light source, or laser diodes, or luminescence elements, and there are three output channels 33, 331 and 3310. Electrical leads to the light sources and to other electronic elements in the integrated system are formed as current paths diffused or alloyed into the basic crystal. In operation each light source emits at least one optical frequency different from the other into the part 32, each beam containing information in the form of modulation or a pulse train. Part of the beam from source 34 is transmitted directly into the output channel 33, while part is reflected at the semi-reflective surface 030 into a polarizer 35 (such as a Glan- Thompson prism), where it acquires an additional physical property, namely a direction of polarization, is reflected back by a mirror 035, and is reflected by surface 030 into output channel 331. Likewise a beam from source 341 is passed partly into output channel 331 and partly into channel 33 after encoding in polarizer 351. The beam entering channel 33 is however, by reflection at semi-reflective surfaces 031 and 032, mixed in a specific intensity proportion with the beam entering channel 331, the mixing ratio being variable by altering the intensity ratio of the sources 34 and 341. The surfaces 031 and 032 also reflect part of the input to each channel into  the third channel 3310, via the optically non-linear crystal 36, which may further encode the beams by non-linear effects such as generation of harmonics or difference frequencies. The beam reflected by the mirror 035 may also be reflected into the emitting source 34, which could lead to self-stimulation, or may pass into the other  polarizer 351. These possibilities may be  obviated by arranging for optical feedback in the sources, and for the polarizers 35 and 351 to be crossed. In a modification, Fig. 2 (not shown), the positions of the source 341 and the polarizer 351 are reversed, so that in the crystal 36 are beams from the source 341 differently polarized in 35 and 351, passing through the crystal as ordinary and extra-ordinary rays. For a given phase adjustment and depending upon the optical path lengths of the beam fractions coupling is produced in the KDP crystal so that a second harmonic of the representative frequency originating in the source 341 is produced. Phase adjustment is achieved, and may be periodically varied, by means of an optical phase-shift element (37), for example a piezoelectrically-controlled crystal, or alternatiyely the mirror 0351 reflecting the beam passing through the polarizer 351 may have electrically controllable reflectivity. The polarizer 351 and phase shift element (37) can however be located outside the integrated system, and indeed may belong to a further integrated system. Thus the beam emitted by source 341 is subjected in the KDP crystal to an additional stage of encoding, the intensity of the second  harmonic therein produced depending on the phase adjustment introduced in the element (37), so that when the phase is modulated by this element the harmonic is also modulated.  In a further modification, Fig. 3 (not shown), the positions of the source 34 and the polarizer 35 are reversed, and an additional phase-shift element (38) is provided, so that a further order of information organization may be introduced. Thus for each modification information derived from the sources 34, 341 and encoded further by the polarizers 35 and 351, optically non-linear crystal 36 and possibly phase shift elements (37) and (38) is radiated out through the output channels 33, 331 and 3310, in each case with a different information structure, so that each makes possible a different composition (i.e. increase in the information content), decomposition (breakdown of the information content to subsidiary pieces) or transposition (conversion to a new or partially new information structure with in addition components of another information structure) of the information content. Thus we have a plurality of hierarchical information organisations which if transmitted to another similar integrated system can react with other information organisations by triggering complex switching operations within the laser network to create new information organisations. The invention is of interest primarily in automatic data processing equipment in the field of cybernetics. Reference has been directed by the Comptroller to Specification 1278668.