Abstract: A waveguide for the extraction of light at low levels of reflection arranged to guide light from an electro-optical component on a chip to a facet on the chip for extraction includes a first part and a second part. The first part (4) is extended, the second part (5) includes a surface (JK) through which the light exits from the waveguide (1). A non-adiabatic longitudinal section (GHLM) is located after the first part (4) but before the surface (JK) in the direction of propagation of the light, and the surface (JK) forms in the plane of the chip a first angle (V1) with the optical axis (A) of the first part (4) that lies between 5 and 80 degrees.

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: An optical light splitter includes or is connected to at least two input waveguides (4; 6, 7; 18, 19; 32,33) for light. The light splitter (1, 2, 30, 40), on the side opposite to the input waveguide or input waveguides (4; 6, 7; 18, 19; 32, 33; 41, 42) transitions into at most one output waveguide (8, 10, 20, 34) in the direction of propagation of the incoming light. A surface (14, 25, 31, 45) is present set at an angle to the direction of propagation of the light in that part of the light splitter that is opposite to the input waveguide or input waveguides, the surface is present where the light splitter has an image from incoming light, and internal corners are not present in the part.

Abstract: A communication system includes a communication unit with a first part and a number of a second part, where the second part is arranged to be placed at the location of an end user, and where the first part is common for a number of second parts. The first part and the second part respectively include a laser, and each second part is connected with the first part by a fiber optic cable and a frequency filter, the first part and the relevant second part being arranged to exchange information by laser light. Each second part includes a tunable laser, the first part is arranged to analyze light received from a second part, and to transmit information to the second part while the first part is receiving light from the second part, and the information contains information for the second part that it should adjust, where required, its frequency or wavelength, and the second part thus is arranged to change its frequency or wavelength.

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 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: A Mach Zehnder (MZ) modulator (1) includes a splitter (4) for splitting incident light in one wave guide (3) into two modulator arms (5,6) of the MZ and a combiner (7) that combines light from the two arms (5,6) into an output mode, where electrodes (9,10) are present in connection with the arms (5,6) for changing the refractive index in the arms in order to modulate incident light so that the light is amplified or so that an extinction, due to interference between the light in the two arms, takes place. The splitter (4) is arranged to split incident light equally into the two arms (5,6) and a part (11) of one of the arms (5) between the electrode (9) and the combiner (7) is designed to cause an intentional loss of light in the wave guide (5), whereby a desired asymmetry in transmission of the two arms (5,6) occurs.

Abstract: An optical light splitter includes or is connected to at least two input waveguides (4; 6, 7; 18, 19; 32,33) for light. The light splitter (1, 2, 30, 40), on the side opposite to the input waveguide or input waveguides (4; 6, 7; 18, 19; 32, 33; 41, 42) transitions into at most one output waveguide (8, 10, 20, 34) in the direction of propagation of the incoming light. A surface (14, 25, 31, 45) is present set at an angle to the direction of propagation of the light in that part of the light splitter that is opposite to the input waveguide or input waveguides, the surface is present where the light splitter has an image from incoming light, and internal corners are not present in the part.

Abstract: A communication system includes a communication unit with a first part and a number of a second part, where the second part is arranged to be placed at the location of an end user, and where the first part is common for a number of second parts. The first part and the second part respectively include a laser, and each second part is connected with the first part by a fibre optic cable and a frequency filter, the first part and the relevant second part being arranged to exchange information by laser light. Each second part includes a tunable laser, the first part is arranged to analyze light received from a second part, and to transmit information to the second part while the first part is receiving light from the second part, and the information contains information for the second part that it should adjust, where required, its frequency or wavelength, and the second part thus is arranged to change its frequency or wavelength.

Abstract: A transition part (1) between two optical waveguides (2,3) with different index contrast is characterised in that the transition part (1) includes a non-adiabatically up-tapered longitudinal section (8), and in that the transition (7) between the two waveguides (2,3) is arranged after the up-tapered longitudinal section (8) as seen along the main direction (L) of propagation of the light. A method of manufacturing the transition part is also described.

Abstract: A waveguide for the extraction of light at low levels of reflection arranged to guide light from an electro-optical component on a chip to a facet on the chip for extraction includes a first part and a second part. The first part (4) is extended, the second part (5) includes a surface (JK) through which the light exits from the waveguide (1). A non-adiabatic longitudinal section (GHLM) is located after the first part (4) but before the surface (JK) in the direction of propagation of the light, and the surface (JK) forms in the plane of the chip a first angle (V1) with the optical axis (A) of the first part (4) that lies between 5 and 80 degrees.

Abstract: An integrated photonic circuit includes waveguides (12-19) and other photonic components. The photonic circuit has a first part (1) and a second part (2), the first part and the second part being connected to a mirror in the form of a half 2×2 multimode interferometer (MMI) (32), which comprises solely one half MMI (31) in a longitudinal direction, the half MMI (32) having two ports (33, 34) and being arranged to reflect half of the light that is incident on one of the ports to one port and transmit half of the incident light to the second port, and the free surface (35) of the half MMI (32) having been treated with a highly reflective material.

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: Device for controlling the current through a PN junction includes a voltage source connected in series to, in order, firstly a controllable current generator having an input connected to the voltage source, an output and a control input, thereafter a measurement resistor connected to the output, and finally a controlled output to which the PN junction is connected. The device further includes a control signal input, a differential amplifier and an integrating device, which includes a balanced integrator. The current through the output of the controllable current generator is proportional to the voltage difference between its input and its control input, and the reference voltage of the integrating device is constituted of the voltage of the voltage source.

Abstract: Method for producing a modulated grating for an optimal reflection spectrum, which grating is a multiple wavelength reflector. The method includes the following steps: a) Determining wavelengths to be reflected b) Calculating a preliminary grating c) Comparing the reflection spectrum ro(f) with the characteristics of the wanted modulated grating d) Differences lead to a directional change of ro(f) e) Calculating a target function G(z) f) Changing the grating (zk) depending on the real and imaginary part of G(z) g) Repeating steps c) to f) until the grating reflects the predetermined wavelengths.

Abstract: A Mach Zehnder (MZ) modulator (1) includes a splitter (4) for splitting incident light in one wave guide (3) into two modulator arms (5,6) of the MZ and a combiner (7) that combines light from the two arms (5,6) into an output mode, where electrodes (9,10) are present in connection with the arms (5,6) for changing the refractive index in the arms in order to modulate incident light so that the light is amplified or so that an extinction, due to interference between the light in the two arms, takes place. The splitter (4) is arranged to split incident light equally into the two arms (5,6) and a part (11) of one of the arms (5) between the electrode (9) and the combiner (7) is designed to cause an intentional loss of light in the wave guide (5), whereby a desired asymmetry in transmission of the two arms (5,6) occurs.

Abstract: A transition part (1) between two optical waveguides (2,3) with different index contrast is characterised in that the transition part (1) includes a non-adiabatically up-tapered longitudinal section (8), and in that the transition (7) between the two waveguides (2,3) is arranged after the up-tapered longitudinal section (8) as seen along the main direction (L) of propagation of the light. A method of manufacturing the transition part is also described.

Abstract: Device for controlling the current through a PN junction includes a voltage source connected in series to, in order, firstly a controllable current generator having an input connected to the voltage source, an output and a control input, thereafter a measurement resistor connected to the output, and finally a controlled output to which the PN junction is connected. The device further includes a control signal input, a differential amplifier and an integrating device, which includes a balanced integrator. The current through the output of the controllable current generator is proportional to the voltage difference between its input and its control input, and the reference voltage of the integrating device is constituted of the voltage of the voltage source.