Abstract: An optical information processing system comprises a coding unit for individually coding a plurality of optical information carrier waves, and a processing unit for processing the plurality of coded waves. The processing unit has a laser for producing laser light through longitudinal laser mode competition among the waves received.

Abstract: In a transmitter in a coherence multiplexed transmission system the output signal of a laser is directly applied to a channel and indirectly via a plurality of cascaded circuits of delay elements and modulators. The modulators vary a component of the autocorrelation function of the output signal of the transmitter as a function of an associated modulation signal (m.sub.1, m.sub.2, m.sub.3). In the receiver the autocorrelation functions values of the channel output signal for delays (D.sub.1, D.sub.2, D.sub.3) are determined in the demodulators. These autocorrelation function values from the modulated signal (m.sub.1 ', m.sub.2 ', m.sub.3 '). To reduce the number of periodic components of the autocorrelation function of the signal source, and hence enhance the possible transmission capacity, the transmitter comprises a decorrelation modulator for modulating the signal source with pulses generated by a pulse generator.

Abstract: The invention relates to an optical switch which is switchable by means of light. The switch includes a directional coupler having four gates, the first gate of which forms part of an input of the switch for receiving an optical data pulse series, the second gate forms part of an output of the switch and the third gate and the fourth gate are interconnected by means of a waveguide structure. This waveguide has a non-linear optical portion at an asymmetrical position in the waveguide. A control pulse signal is also introduced into the waveguide via the first gate of the directional coupler. The waveguide is asymmetrical for the data pulse series and symmetrical for the control pulse signal.

Abstract: In a sychronizing arrangement for synchronizing two streams of optical pulses, the problem arises that for pulse frequencies above 10 GHz the operation of the synchronizing arrangement becomes increasingly difficult. To overcome that problem it has been proposed to use a phase locked loop having an optical phase detector, but prior art optical phase detectors have low efficiency and was rather complex. According to the invention an optically controlled optical switch is used as the phase detector.

Abstract: An optical communication system includes a directly modulated semiconductor laser (10), the output of which results in pulse shortening of light pulses corresponding to high level bits of a high frequency electrical digital modulating signal. A travelling wave laser amplifier (14) coupled to the laser provides an amplified modulated light signal to an optical channel (16), and an optical detector (18) converts a light signal received from the optical channel into an electrical signal. The amplifier has an overshoot characteristic which provides an extended output when overdriven by a high level optical input pulse, and the modulated laser is arranged to provide such high level pulses. The overshoot characteristic of the amplifier thus compensates for pulse shortening produced by the modulated laser in the case of isolated high level bits and the initial bit of a stream of high level bits. The invention also relates to a transmitter and to a repeater for use in such an optical communication system.

Abstract: The invention relates to an optical unit for generating an optical data signal in conformity with a data pattern. The unit has an input for receiving the data pattern with a modulation period T, a pulsed laser for supplying an optical pulse series having a pulse period n.T and a pulse duration .tau., in which n is an integer, and a converting unit for converting this pulse series into an optical data signal in conformity with the data pattern. The converting unit is a radiation-controlled optical switch. This switch has a first input for receiving the data pattern in the form of an optical pulse series whose pulses have a pulse width b, a second input for receiving the optical pulse series from the pulsed laser for sampling the data pattern during periods when the switch is open, and an output for supplying a data pulse series having a pulse width .epsilon..b, in which 0 <.epsilon.<1.

Abstract: A unit for generating signal pulses. comprises a first, pulsed laser for supplying a pulse series having a pulse period T and a wavelength .lambda..sub.1, and a modulation unit comprising a second laser. The second laser has a wavelength band which is different from .lambda..sub.1 and can be modulated at a modulation period T in accordance with a data signal to be transported. The radiation from the second laser ) can be injected into the first laser at instants for which it holds that E(P.sub.m)>E(LP.sub.i), in which E(P.sub.m) is the radiation energy of the second laser injected into the first laser at the relevant instant and E(LP.sub.i) is the radiation energy built up in the first laser at the relevant instant. Moreover, the unit comprises a wavelength discriminator which selects the pulses of wavelength .lambda..sub.1 from the radiation emitted by the first laser after injection.

Abstract: An optical signal-regenerating unit for a received optical signal pulse series (S.sub.1) having a modulation period T and a wavelength .lambda..sub.d. The optical unit includes a pulsed laser for producing a regenerated pulse series S.sub.2 having a pulse period equal to the modulation period T. Pulses of the received pulse series S.sub.1 are injected into the pulsed laser at instants at which the energy of the injected pulse exceeds the energy of a pulse then being built up in the laser. By maintaining that relationship, the multimode spectrum of the pulse laser is converted into a single mode spectrum having a wavelength equal to the wavelength .lambda..sub.d of the received radiation.

Abstract: 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.

Abstract: The invention relates to an optical switch (1) which is switchable by means of light. The switch (1) comprises an optical wave-guiding structure (3) having an entrance (5) to which a signal can be applied and an exit (7). The refractive index of the wave-guiding structure (30) is variable by means of light intensity. The switch (1) further comprises a radiation source unit (15) whose radiation can be injected into the wave-guiding structure (3). The radiation source unit (15) comprises a pulsed laser (17) having a repetition time T and a pulse duration p and a medium (19) for transporting the radiation supplied by the laser (17). The radiation source unit (15) is provided with setting means (21 ) for stabilizing the wavelength of the laser (17) at a number n of selected wavelength bands from a number N of possibly selectable wavelength bands within one and the same pulse supplied by the laser (17). Moreover, the medium (19) is dispersive at a wavelength-dependent travel time t.sub.

Abstract: A doubler for a pulsed multimode laser diode. A controllable feedback loop controls the laser output such that one of the output wavelengths, or the average of two of them, fall within the acceptance bandwidth of a non-linear optical medium. Alternatively, radiation emitted from the pulsed laser is reflected over a path length such that reflected energy reenters the laser during the build-up of a following pulse.

Abstract: Radiation-emitting semiconductor diodes in the form of diode lasers or LEDs are used inter alia in information processing systems. There is a particular demand for diodes having a low wavelength. A diode laser which emits at 633 nm is a particularly attractive alternative to a helium-neon gas laser. According to the invention, a method of making a the buffer layer of such a radiation-emitting semiconductor diode comprises aluminium-gallium arsenide, the aluminium content having at least a minimum value belonging to the band gap of the active layer. The minimum Al content is approximately 6 at % for an InGaP band gap of 1.88 eV, and approximately 9 at % for 1.92 eV. As a result, an active layer comprising InGaP emits, for example, at 650 nm while the semiconductor layers still possess a good crystal quality and morphology. When the active layer of a diode laser has a multiple quantum well structure with comparatively thick (approximately 5 nm) well layers, it even emits at 633 nm.

Abstract: An optical device (7) for use in optical write, read, inspection or measuring apparatuses comprising a diode laser (8) for generating a radiation beam (11) and an optical system (9) for concentrating and guiding the radiation beam. The diode laser is a pulsed laser and a feedback element is arranged in the radiation path at a specific distance (d) from the diode laser. By giving the element a suitable reflection coefficient, a stabilized radiation beam is obtained. The beam direction can be varied by rendering the wavelength adjustable and by making use of a dispersive element.

Abstract: Radiation-emitting semiconductor diodes in the form of diode lasers or LEDs are used inter alia in information processing systems. There is a particular demand for diodes having a low wavelength. A diode laser which emits at 633 nm is a particularly attractive alternative to a helium-neon gas laser.A radiation-emitting semiconductor diode comprising a semiconductor body with a semiconductor substrate of a first conductivity type on which are present at least a buffer layer of the first conductivity type, a first cladding layer of the first conductivity type and made of InAlGaP, an active layer of InGaP or InAlGaP, and a second cladding layer of the second conductivity type and also made of InAlGaP does not fully meet these demands: either the wavelength is comparatively high owing to the occurrence of an ordered structure, or the morphology and crystal quality of the layers is poor.

Abstract: Radiation-emitting semiconductor diodes in the form of a laser diode or an LED form important components in information processing systems. There is a particular demand for diodes emitting in the visible range of the spectrum and having a high permissible operating temperature. A radiation-emitting diode including a semiconductor body with a semiconductor substrate on which a lower cladding layer, an active layer, and an upper cladding layer are present, the active layer and the two cladding layers each including different semiconductor materials which form a mixed crystal, partly fulfill the above requirements. According to the invention, such a diode is characterized in that the mixed crystal of the active layer is more strongly ordered than that of the two cladding layers. This makes the difference in bandgap between these layers greater than in the known diode. The diode thus has a comparatively high T.sub.o value and accordingly a high maximum operation temperature.