摘要:
Broad-band communication system comprising a broad-band cable network arranged between an exchange and a large plurality of subscriber's stations. The network is formed by optical fibers. In order to avoid extra attenuation caused by splices, the incoming bundles of individual cables are, split at branching points, without splicing, into a number of separate outgoing bundles of individual cables.
摘要:
In an optical soliton transmission system an optical transmitter (2) generating short pulses is coupled to a glass fiber cable (4) comprising sections of glass fiber (7, 9, 11, 13, 15) with interspaced semiconductor laser amplifiers (8, 10, 12, 14). An optical receiver (6) is connected to the end of the glass fiber cable (15). In optical soliton transmission Erbium doped fiber amplifiers and dispersion shifted fiber are currently used in the 1.5 .mu.m wavelength region. However, by utilizing standard fiber in the 1.3 .mu.m wavelength region it is possible to use a lower soliton power compared with a state-of the-art transmission system.
摘要:
In an optical heterodyne or homodyne receiver an optical system (140) is used in which the local oscillator beam (L) is combined with the signal beam (S). Simultaneously, these beams are split into orthogonally polarized sub-beams. For this purpose the optical system (140) comprises polarization-sensitive beam-splitting layers (141a and 141b) and neutral beam-splitting layers (142a and 142b) which function as beam-combining elements. In order to align the directions of the exit sub-beams of the signal beam (.sub.11, S.sub.12, S.sub.2, S.sub.22) and the local oscillator beam (L.sub.11, L.sub.12, L.sub.21, L.sub.22), the angles (.alpha., .beta., .gamma., .delta.) enclosed by the beam-splitting faces are chosen to be such that two angles located opposite each other have a combined magnitude of 180.degree.. This is realised by providing the layers (141a, 142b and 141b, 142a) on side faces of one prism (140a, 140b).
摘要:
A monomode optical transmission fibre (1) is described, having a tapered end portion (5) on which a lens (10) is arranged. This lens is obtained by immersing the fibre end in a transparent liquid material (7) whose melting temperature is lower than that of the fibre materials and whose refractive index is substantially equal to that of the fibre core (2), and by allowing the drop which adheres to the fibre after withdrawal to solidify.
摘要:
The invention relates to an optical demultiplexer whose "color band" is adjustable, so that the demultiplexer can always be adapted to future standards. The adjustment is performed either by tilting the optical grating with respect to the light beam incident thereon or by deflecting the light by means of a liquid crystal arranged in the light path.
摘要:
On a support which supports a light-emitting semiconductor device there is arranged a cap which is hermetically sealed to the support. In the cap there is provided a transparent plate, an inner layer of which facing the semiconductor device consists of a material having a high refractive index (>1.7). On the outer side of the plate there is provided a layer of photosensitive lacquer which is exposed to the light emitted by the semiconductor device. After development of the layer of lacquer, only the exposed part which is situated opposite the semiconductor device remains. This part is heated to the melting point, thus forming a droplet of lacquer, after which the outer layer of the plate and the droplet of lacquer are removed by way of a non-selective etching method, so that a lens which is situated opposite the semiconductor device and a flat window which surrounds the lens are automatically formed at the same time.
摘要:
A coupling element for coupling a laser radiation source to a monomode optical transmission fiber. The end of the fiber is monotonically flattened at a temperature at which the fiber core has a viscosity of between 10.sup.7 to 10.sup.8.5 poises. The fiber has a cladding glass chosen to have a viscosity of between 10.sup.10 -10.sup.11 poises at the flattening temperature. This causes the core glass to emerge in the form of a semi-ellipsoidal lens, when the fiber is flattened.
摘要:
A device for optical heterodyne detection is described, using only two adjustable elements influencing the state of polarisation and having a limited control range (51, 52) in order to realize an endless polarisation control. In a first embodiment a temporary loss of signal intensity of at most 3 dB is accepted. This signal loss is avoided if a circuit of non-adjustable optical components (81, 82, 83) is incorporated in the heterodyne detection device.
摘要:
A ball lens connector part having low total reflections as well as a method of manufacturing such a ball lens connector part are described. The total reflections can be limited to less than -60 dB by means of the present ball lens connector part. The ball lens connector part comprises a fiber with an inclined fiber end in a tubular housing which housing further comprises a ball lens. If the ball lens comprises a flat surface, the total reflections can be lower than -80 dB. By subjecting the end of the housing to a machining treatment, the center line of the said end is moved in such a manner that it coincides with the optical axis of the emanating light beam.
摘要:
An optical transmission system is described which comprises a radiation source (30) and a multiple-clad monomode optical transmission fibre (10) with a negative-step index profile. In order to improve the efficiency of coupling the radiation from the source into the transmission fibre a single-clad-monomode transmission fibre (20), whose end portion which faces the source is tapered, is arranged between the source and said fibre.