An optical semiconductor device includes a chassis that has an external wall, a feedthrough that penetrates the external wall of the chassis and has a projection portion projecting toward outside of the chassis from the external wall, a connection terminal that is electrically connected to a component mounted in the chassis and is on the projection portion of the feedthrough, a first temperature detector that is on an external face of the external wall of the chassis and detects a temperature of the chassis, and a flexible substrate of which an end is connected to the connection terminal and of which a portion spaced from the end is connected to the first temperature detector, wherein the first temperature detector is between the external wall and the flexible substrate.

A method for sweeping an electromagnetic radiation source (12) to produce single mode operation having an optimized side-mode suppression ratio over a continuous range of wavelengths within a prescribed temporal profile, the electromagnetic radiation source is configured to output electromagnetic radiation at a given wavelength based upon parameters. The method includes determining a set of parameter combinations that satisfy a condition for a desired set of wavelengths and a maximum side mode suppression ratio over the range of wavelengths. The set of parameter combinations define sub-paths for transitioning from one wavelength to another wavelength. Combinations of select sub-paths provide a multivariate path for transitioning over the range of wavelengths. The method also includes controlling the semiconductor laser to emit electromagnetic radiation over the range of wavelengths by traversing the multivariate path in a desired manner.

A test apparatus and a method for operating a data processing system to generate a test signal for testing a DUT are disclosed. The apparatus includes a signal generator, artificial neural network, and controller. The signal generator generates a test signal determined by a plurality of signal generator input parameters, X, that are coupled thereto. The test signal is characterized by a plurality of calculated parameters, Y. The artificial neural network has the calculated parameters as inputs and a plurality of outputs connected to the plurality of signal generator inputs. The controller receives desired values for the calculated parameters and couples those desired values to the neural network inputs, thereby causing the test signal generator to generate a test signal having the desired values for the calculated parameters.

A wavelength-tunable light source includes a wavelength-tunable laser including a first region and a second region each of which includes at least one of heaters, a frequency locker configured to receive output light of the wavelength-tunable laser and output two electric control signals whose phases are mutually different by 90° and having frequency period with respect to frequency of the output light, a thermal electric cooler on which the wavelength-tunable laser and the frequency locker are mounted, and a controller configured to control temperature of the heaters, and the thermal electric cooler on the basis of any one of the two electric control signals.

A distributed feedback plus reflection (DFB+R) laser includes an active section, a passive section, a low reflection (LR) mirror, and an etalon. The active section includes a distributed feedback (DFB) grating and is configured to operate in a lasing mode. The passive section is coupled end to end with the active section. The LR mirror is formed on or in the passive section. The etalon includes a portion of the DFB grating, the passive section, and the LR mirror. The lasing mode of the active section is aligned to a long wavelength edge of a reflection peak of the etalon.

A two-kappa DBR laser includes an active section, a HR mirror, a first DBR section, and a second DBR section. The HR mirror is coupled to a rear of the active section. The first DBR section is coupled to a front of the active section, the first DBR section having a first DBR grating with a first kappa κ1. The second DBR section is coupled to a front of the first DBR section such that the first DBR section is positioned between the active section and the second DBR section. The second DBR section has a second DBR grating with a second kappa κ2 less than the first kappa κ1. The two-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection profile that includes a DBR reflection peak. The lasing mode is aligned to a long wavelength edge of the DBR reflection peak.

A semiconductor optical device includes a substrate containing silicon and having a waveguide, a first semiconductor element including a core layer formed of III-V group compound semiconductors and being bonded to the substrate, and a second semiconductor element including a diffraction grating and being bonded to the substrate, wherein the diffraction grating has a first semiconductor layer and a second semiconductor layer burying the first semiconductor layer, the first semiconductor layer and the second semiconductor layer are formed of III-V group compound semiconductors, and the diffraction grating reflects light propagating through the waveguide.

An isolator-free laser includes an etalon, an active section, and a low reflection (LR) mirror. The etalon includes a passive section of the isolator-free laser and a reflection profile. The active section is coupled end to end with the passive section. The active section has a distributed feedback (DFB) grating and a lasing mode at a long wavelength side of a reflection peak of the reflection profile. The LR mirror is formed on a front facet of the passive section. The long wavelength edge of the reflection peak of the reflection profile may have a slope greater than 0.006 GHz.sup.1. A RIN of the isolator-free laser under 20 decibels (dB) external cavity optical feedback may be less than or equal to 130 dBc/Hz.

A wavelength tunable laser device includes a substrate including silicon, the substrate having a waveguide, a first semiconductor element bonded to the substrate, the first semiconductor element including an active layer of a group III-V compound semiconductor, and a second semiconductor element bonded to the substrate, the second semiconductor element facing to the first semiconductor element in a direction along which light emitted from the first semiconductor element propagates, the second semiconductor element including a grating formed of a group III-V compound semiconductor. The grating selects a wavelength of light.

A semiconductor laser device is a vernier-type wavelength-tunable semiconductor laser device including an optical resonator, constituted by first and second reflective elements having reflection comb spectra in which reflection peaks are arranged on a wavelength axis in a substantially periodic manner and having mutually different periods. At least one of the first and second reflective elements has a sampled grating structure having a reflection comb spectrum in which reflection phases at the respective reflection peaks are aligned and the intensity of a reflection peak outside a set laser emission wavelength bandwidth is lower than the intensity of a reflection peak within the laser emission wavelength bandwidth.