Syntune Ab

Finisar Sweden Ab

Finisar Corporation

Urban Eriksson

Robert Lewén

Jan-Olof Wesstrom

Jan-Olof Wesström

Filip Öhman

Edgard Goobar

Christopher Daunt

Peter Szabo

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 2unique symbols, the light led through each respective path is phase shifted using 2&#x2212;1 variable part phase shifts, and the respective difference between the respective predetermined values is the same for all variable part phase shifts.

Method for modulating a carrier light wave

A laser device () includes a laser () in turn including at least one Distributed Bragg Reflector (DBR) section (), at least one phase section () and at least one gain section (), further including a laser control element (), a feedback control element () and a frequency noise discriminator (), 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.

Semiconductor laser device

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.

Method for calibrating a tunable laser

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.

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. The two branch currents are controlled within a certain modeflat so that the laser operation point does not coincide with the center of the modeflat, but is sufficiently far from the periphery of the modeflat for mode transitions not to occur, within a predetermined time period, as a consequence of changes related to ageing of the laser, leading to drift of the laser operation point.

Method for suppressing side modes in a tunable laser

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 nhaving an optical signal propagating at an optical velocity v, and a microwave transmission line with an electrical propagation index n, having an electrical signal propagating at an electrical velocity V. The electrical propagation index nof the unloaded microwave transmission line is lower than the optical group index nof the optical waveguide. The loading and length of the microwave transmission line are adjusted for a specific Bloch impedance and electrical velocity v. The invention also relates to a method for adapting the impedance of an optical modulator.

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Bromma, Sweden

Urban Eriksson