摘要:
A two way transmission system has a source at one terminal and a fibre loop at the other terminal. Conventional modulation techniques are used at the terminal with the source, whereas at the other terminal modulation is achieved by modulation of the birefringence of the loop.
摘要:
An optical fiber laser comprises an optical resonant cavity defined by an optical fiber (1). First and second reflectors (8, 13; 14, 19) are optically coupled with respective ends of the fibre. The first reflector is adapted to reflect radiation at the lasing wavelength and the second reflector to be partially transparent to radiation at the lasing wavelength. Each reflector comprises a directional coupler (8; 14) having first and second pairs of ports. One each of the one pair of ports (11; 16) of each coupler (8; 14) is optically coupled with the cavity (1) while both ports of the other pair (9, 10; 17,18) are coupled with a respective loop of optical fibre (13, 19). The remaining port (12) of one coupler (8) is connected with a source of pumping radiation (6), and the remaining port (15) of the other coupler (14), is available to output laser radiation.
摘要:
An optical 1.times.N star coupler has a single mode input fibre (I) and N single mode output fibres (O.sub.1) forming an output fibre assembly. The output fibres (O) are tapered within a former (2) which holds each output fibre (O) so it is positioned substantially identically relative to the remaining output fibres. The input fibre (I) is also tapered such that the fundamental mode field of the input fibre (I) and output fibre assembly are substantially equal. The identical relative positions of the output fibres (O) provides a wavelength independent 1.times.N star coupler.
摘要:
A technique for reducing splice loss between similar or dissimilar optical fibres. Two fibers (10,11) are joined by fusion splicing and the joint region is tapered until the cladding assumes a guiding function. This produces a mode transformer which covers the fundamental mode of one fibre to that of the other with little or negligible loss.
摘要:
Six secondary optical fibres (20) are located about and parallel to a central optical fibre (21) by a capillary tube (22) to form a fibre bundle which is then formed into a fused, tapered coupler in which the tapering is stopped when the proportions of light coupled out of the central fibre (21) at 1.3 and 1.53 .mu.m are first equal. The fusion process can provide sufficient fusion between the central fibre and each secondary fibre to provide a 1 to (n+1) coupler where n is the number of secondary fibres. This method provides a coupler which is wavelength-flattened between 1.3 and 1.53 .mu.m using similar fibres.
摘要:
Method and apparatus for fabricating fused optical fibre devices includes a furnace provided with an electric heating element. A heat-distributing insert is provided within the heating element, the heating element and the insert being sized and shaped to define a heating chamber for an optical fibre arrangement. The method includes passing electric current through the heating element, and supplying and maintaining an inert atmosphere within the heating chamber.
摘要:
A method of forming a multiport optical fiber coupler in which a bundle of seven optical fibers are located in close-packed hexagonal array within a capillary tube and twisted. An optical source is coupled to an outer fiber. A fused, tapered coupler is formed, the tapering being stopped when the minimum of optical power outputs is first maximized. This provides a 6.times.7 optical fiber coupler. Also disclosed is a 7.times.7 optical fiber coupler formed by fusing the coupler during formation sufficiently to provide that the maximum insertion loss through the device between any input and output is minimized.
摘要:
Apparatus for fabricating fused optical fibre devices comprises a furnace provided with an electric heating element (5). A heat-distributing insert (7) is provided within the heating element (5), the heating element and the insert being sized and shaped to define a heating chamber for an optical fibre arrangement. The apparatus includes means for passing electric current through the heating element (5), and means (8) for supplying and maintaining an inert atmosphere within the heating chamber.
摘要:
A fused optical fibre coupler in which one of the fibres has a propagation constant which in the coupling region is slightly different from that of the other. The propagation constant difference can be arranged to provide selected splitting ratios over a relatively wide wavelength range.