Abstract: Method for modulating a carrier light wave to achieve, a modulated light wave which carries information by symbols selected from a set of at least two different symbols. The light led through each path is phase-shifted by a respective total variable part phase shift, which for each path is the sum of at least three respective variable part phase shifts. Each variable part phase shift for each modulation state assumes one of two respective predetermined values, and each symbol is modulated using a respective combination of two such total variable part phase shifts. The modulation performed by the two paths is a PSK (Phase Shift Keying) modulation scheme, the group of symbols includes 2N unique symbols, the light led through each respective path is phase shifted using 2N?1 variable part phase shifts, and the respective difference between the respective predetermined values is the same for all variable part phase shifts.

Abstract: Method for modulating a carrier light wave to achieve, a modulated light wave which carries information by symbols selected from a set of at least two different symbols. The light led through each path is phase-shifted by a respective total variable part phase shift, which for each path is the sum of at least three respective variable part phase shifts. Each variable part phase shift for each modulation state assumes one of two respective predetermined values, and each symbol is modulated using a respective combination of two such total variable part phase shifts. The modulation performed by the two paths is a PSK (Phase Shift Keying) modulation scheme, the group of symbols includes 2N unique symbols, the light led through each respective path is phase shifted using 2N?1 variable part phase shifts, and the respective difference between the respective predetermined values is the same for all variable part phase shifts.

Abstract: A laser device (100) includes a laser (110; 210; 310; 410; 510) in turn including at least one Distributed Bragg Reflector (DBR) section (111), at least one phase section (112) and at least one gain section (113), further including a laser control element (150), a feedback control element (140) and a frequency noise discriminator (130,131), which feedback control element is arranged to feed a variable feedback signal to at least one of the at least one DBR section and the at least one phase section of the laser, so that the output laser frequency is altered in response to a variation in the feedback signal or the combination of respective feedback signals, whereby the feedback signal or combination of respective feedback signals is varied as a function of the detected frequency fluctuation so as to counteract the detected frequency fluctuation.

Abstract: Method for calibrating and tuning a part wise monotonically, continuously tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, are applied, which laser is not actively cooled, includes a) a calibration step, including obtaining at least two tuning lines along which tuning lines all combinations of phase and Bragg currents are stable operating points, identifying at least one reference stable operating point along a first one of the identified tuning lines at which operating point the laser emits light at a certain reference frequency, and storing at least one reference stable operating point; and b) a subsequent tuning step, during which the output frequency of the laser in relation to the reference frequency is controlled to a desired output frequency by translating the operating point of the laser along the first tuning line.

Abstract: Method for calibrating a tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, is applied, includes: a) selecting a phase current; b) identifying a range of reflector currents that achieves emission of light from the laser within a desired frequency band; c) scanning the reflector current(s) over the range of reflector currents, for each of at least two different phase currents, and reading the relative output power of the laser for each point scanned; d) identifying one stable operating point; e) identifying and storing one stable, continuous tuning line as constructed by interpolating; f) calibrating the laser frequency and observing a fed back signal from a target for the light emitted from the laser; g) measuring the temperature of the laser; and h) storing temperature and one operating point along the tuning line.

Abstract: Method for calibrating and tuning a part wise monotonically, continuously tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, are applied, which laser is not actively cooled, includes a) a calibration step, including obtaining at least two tuning lines along which tuning lines all combinations of phase and Bragg currents are stable operating points, identifying at least one reference stable operating point along a first one of the identified tuning lines at which operating point the laser emits light at a certain reference frequency, and storing at least one reference stable operating point; and b) a subsequent tuning step, during which the output frequency of the laser in relation to the reference frequency is controlled to a desired output frequency by translating the operating point of the laser along the first tuning line.

Abstract: Method for calibrating a tunable semiconductor laser having a phase section and a first Bragg reflector section, through which sections a phase current and a first reflector current, respectively, is applied, includes: a) selecting a phase current; b) identifying a range of reflector currents that achieves emission of light from the laser within a desired frequency band; c) scanning the reflector current(s) over the range of reflector currents, for each of at least two different phase currents, and reading the relative output power of the laser for each point scanned; d) identifying one stable operating point; e) identifying and storing one stable, continuous tuning line as constructed by interpolating; f) calibrating the laser frequency and observing a fed back signal from a target for the light emitted from the laser; g) measuring the temperature of the laser; and h) storing temperature and one operating point along the tuning line.

Abstract: Method for suppressing side modes during use of a tunable laser of MGY type, having an amplification section, a phase section and a reflector section having a Y-branched waveguide, with a first a second branch, where the laser operation point is defined by feeding a respective current through the phase section, the first and the second branch, where possible combinations of these currents span a three-dimensional space, in which elongated volumes define combinations of currents for which the laser is operated in the same mode and where two-dimensional sections, defined by holding the current through the phase section constant and varying the currents through the branches, through a certain of the volumes constitute modeflats.

Abstract: Method for suppressing side modes during use of a tunable laser of MGY type, having an amplification section, a phase section and a reflector section having a Y-branched waveguide, with a first a second branch, where the laser operation point is defined by feeding a respective current through the phase section, the first and the second branch, where possible combinations of these currents span a three-dimensional space, in which elongated volumes define combinations of currents for which the laser is operated in the same mode and where two-dimensional sections, defined by holding the current through the phase section constant and varying the currents through the branches, through a certain of the volumes constitute modeflats.

Abstract: The present invention relates to an optical modulator, divided into at least two active segments separated by at least one passive segment. The modulator comprises: an optical waveguide with an optical group index no having an optical signal propagating at an optical velocity vo, and a microwave transmission line with an electrical propagation index np, having an electrical signal propagating at an electrical velocity Ve. The electrical propagation index np of the unloaded microwave transmission line is lower than the optical group index no of the optical waveguide. The loading and length of the microwave transmission line are adjusted for a specific Bloch impedance and electrical velocity ve. The invention also relates to a method for adapting the impedance of an optical modulator.

Abstract: The present invention relates to an optical modulator, divided into at least two active segments separated by at least one passive segment. The modulator comprises: an optical waveguide with an optical group index no having an optical signal propagating at an optical velocity vo, and a microwave transmission line with an electrical propagation index np, having an electrical signal propagating at an electrical velocity Ve. The electrical propagation index np of the unloaded microwave transmission line is lower than the optical group index no of the optical waveguide. The loading and length of the microwave transmission line are adjusted for a specific Bloch impedance and electrical velocity ve. The invention also relates to a method for adapting the impedance of an optical modulator.

Abstract: A method of producing a distributed reflector that includes a grating, wherein regions (21) are provided in the grating material transversely to the longitudinal axis of the grating, wherein the refractive index in said regions is lower or higher than the refractive index in surrounding parts of the grating, and wherein the distance between mutually adjacent regions (22) is varied. The invention is characterised by giving the regions (21) mutually the same width, and determining the positions of the various regions along the longitudinal axis (X) of the grating in relation to the wavelengths to be reflected.

Abstract: A method of producing a distributed reflector that includes a grating, wherein regions (21) are provided in the grating material transversely to the longitudinal axis of the grating, wherein the refractive index in said regions is lower or higher than the refractive index in surrounding parts of the grating, and wherein the distance between mutually adjacent regions (22) is varied. The invention is characterised by giving the regions (21) mutually the same width, and determining the positions of the various regions along the longitudinal axis (X) of the grating in relation to the wavelengths to be reflected.

Abstract: A heterobipolar transistor HBT and a laser diode LD are manufactured from a common epitaxial structure having a plurality of semiconducting layers. The transistor can be manufactured directly from the material as it is after finishing the epitaxial steps. For manufacturing the laser diode the structure is changed by diffusing zinc into the material, so that the topmost material layers change their dopant type from n-type to p-type. This is made on selected areas of a wafer, so that transistors and laser diodes thereby can be monolithically integrated. The active region of the laser is located in the collector of the transistor, which gives a freedom in designing the components and results in that an individual optimization of the two components can be made. The laser and the HBT can thus be given substantially the same structures, as if they had been individually optimized. The laser will for example be the type vertical injection and can therefor get the same performance as discrete lasers.

Abstract: In order to reduce the risk of hearing damage to musicians, for example, there is suggested according to the invention a device which comprises, firstly, a floor stand portion with a foot and a post extending upright therefrom, and, secondly, a hearing protector portion mounted on an upper portion of the post. The hearing protector portion is essentially U-shaped, as seen in plan view, in order to be able, as needed, to screen off the ears from intense sound sources located behind and to the sides. The hearing protector portion is displaceable between an advanced active position and a retracted passive position.