Abstract: An optical communication module includes an optical radiation source as well as control circuitry to control the temperature and the power emitted by he optical source. In order to permit soft start-up of the source while avoiding undesired wavelength variations, the optical source is pre-heated before being caused to emit optical radiation. This may be effected by initially heating the optical source to an initial temperature using the thermoelectrical conditioner associated therewith as a heater and subsequently causing a partly under-threshold current to flow through the source, thus causing the source to be heated while still emitting negligible optical power.

Abstract: An optical communication module includes an optical radiation source as well as control circuitry to control the temperature and the power emitted by the optical source. In order to permit soft start-up of the source while avoiding undesired wavelength variations, the optical source is pre-heated before being caused to emit optical radiation. This may be effected by initially heating the optical source to an initial temperature using the thermoelectrical conditioner associated therewith as a heater and subsequently causing a partly under-threshold current to flow through the source, thus causing the source to be heated while still emitting negligible optical power.

Abstract: A receiver for optical signals arranged in packets of data having a discontinuous flow pre-reads the signal and generates, for each packet, a corresponding signal indicating the phase of the data in the packet, and a threshold level indicating the packet mean signal power. A delay line delays the discontinuous flow by a delay interval. A receiver responsive to the discontinuous flow delayed by the delay line performs, on each packet, a receiving operation on the basis of the threshold level and with a phase identified on the basis of the phase indicating signal.

Abstract: An optical communication module includes an optical radiation source as well as control circuitry to control the temperature and the power emitted by the optical source. In order to permit soft start-up of the source while avoiding undesired wavelength variations, the optical source is pre-heated before being caused to emit optical radiation. This may be effected by initially heating the optical source to an initial temperature using the thermoelectrical conditioner associated therewith as a heater and subsequently causing a partly under-threshold current to flow through the source, thus causing the source to be heated while still emitting negligible optical power.

Abstract: An arrangement for monitoring the main radiation beam emitted by an optical source such as a laser diode (10) having a nominal emission wavelength, includes first (18) and second (20) photodetectors as well as a wavelength selective element (22). A beam splitter module (16) is provided for splitting a secondary beam from the main radiation beam of the laser source and directing it towards the first (18) photodetector via the associated wavelength selective element (22). The wavelength selective element (22) has a wavelength selective transmittance-reflectance characteristic, whereby said secondary beam is partly propagated towards said first (18) photodetector and partly reflected from said wavelength selective element (22) towards the second (20) photodetector. The output signals (18a, 20a) from the photodiodes (18, 20) have intensities whose behaviours as a function of wavelength are complementary to each other.

Abstract: A system for controlling the operating parameters of an optical source (1), such as a laser diode in a transmitter module for optical communications, includes:

Abstract: An optical communication module includes a radiation source such as a laser diode (1) as well as control circuitry (2 to 8) to control the temperature and the power emitted by the optical source. In order to permit soft start-up of the source (1) while avoiding undesired wavelength variations, the optical source (1) is pre-heated before being caused to emit optical radiation. This is preferably effected by initially heating the optical source (1) to an initial temperature using the thermoelectrical conditioner associated therewith as a heater and subsequently causing a partly under-threshold current to flow through the source (1), thus causing the source to be heated while still emitting negligible optical power.

Abstract: A device for monitoring the emission wavelength of a laser includes a semiconductor slice or slab having first and second opposed surfaces. The semiconductor slice is exposed to the radiation at an angle such that a portion of said radiation impinges onto the first surface at angles in the vicinity of the Brewster angle for the first surface. The radiation is thus refracted into the semiconductor slice and caused to propagate towards the second surface of the semiconductor slice. A wavelength selective filter is arranged at said second surface having associated a photodetector to generate a signal indicative of the wavelength of the radiation.

Abstract: A device for monitoring the emission wavelength of a laser (10) includes a semiconductor slice or slab (14) having first (141) and second (142) opposed surfaces. The semiconductor slice (14) is exposed to the radiation at an angle such that a portion of said radiation impinges onto the first surface (141) at angles in the vicinity of the Brewster angle for the first surface (141). The radiation is thus refracted into the semiconductor slice (14) and caused to propagate towards the second surface (142) of the semiconductor slice (14). A wavelength selective filter (15) is arranged at said second surface (142) having associated a photodetector (11) to generate a signal (110) indicative of the wavelength of the radiation.

Abstract: The optical add/drop multiplexer has a pair of nominally identical interference filters, one of which carries out the function of extracting a carrier from a wavelength division multiplexed stream and the other the insertion function. The filters are arranged in parallel planes and are secured to opposite faces of a transparent plate so that the stream exits the device after having undergone reflection by both filters. The plate is mounted on a support which can be rotated in either direction to vary the tuning wavelength of the filters.

Abstract: In a ring network communication structure for communication on an optical carrier (3A, 3B), a plurality of nodes (2A, . . . , 2E) are interconnected by means of connections comprising at least a first (3A) and a second (3B) optical carrier, such as an optical fiber. Transmission occurs on the ring according to a WDM scheme, by utilizing a first wavelength (.lambda..sub.1) for communication in one direction on the first carrier (3A) of said pair, while communication in the opposite direction occurs by employing a second wavelength (.lambda..sub.2) on the other optical carrier (3B). In the presence of a failure on one of the connections, the nodes adjacent (2B, 2C) to the failed connection reconfigure themselves to ensure the continuation of communication on the alternative path provided by the ring, by utilizing the first wavelength (.lambda..sub.1) on the second carrier (3B) and the second wavelength (.lambda..sub.2)on the first carrier (3A). Preferential application to SDH optical fiber ring networks.