Fujitsu Corporation

Yuji Kotaki

Manabu Matsuda

Shouichi Ogita

Kazumasa Takabayashi

Ken Morito

Hiroshi Onaka

Haruhiko Tabuchi

Tadao Nakazawa

Martin Bouda

Naoki Hashimoto

Takuya Fujii

Mitsuru Ekawa

Martin c/o Fujitsu Limited Bouda

There is provided a phase control portion for controlling phase of a laser beam resonated in a resonator based on detected results by two optical detectors. The phase control portion adjusts the longitudinal mode positions by a feedback control so that a ratio of intensities detected by the two optical detectors comes to a predetermined reference value. To one of the optical detectors, part of a laser beam outputted from the resonator is irradiated as it is, whereas, to the other one of the optical detectors, part of the laser beam outputted from the resonator is irradiated after passing through an etalon. An FSR of the etalon is a double of that of another etalon in the resonator.

Wavelength tunable laser and method of controlling the same

A wavelength-selectable laser with a resonance region formed by two reflecting surfaces include a gain medium generating a laser beam, a first filter, and a second filter. The first filter has a first controllable transmission region and transmits a first predetermined wavelength region of the laser beam generated in the gain medium, the first predetermined wavelength region matching the first controllable transmission region. The second filter has a plurality of periodically arranged second transmission regions and transmits a second predetermined wavelength region of the laser beam transmitted by the first filter, the second predetermined wavelength region matching one of the second transmission regions.

Wavelength-selectable laser capable of high-speed frequency control

A first layer of InP is deposited on a diffraction grating so as to cover it, by MOCVD in which PH or organophosphorus is used as a source material of P and in which H is used as a carrier gas. The substrate is heated up to a temperature which is higher than the substrate temperature during the first layer deposition, and then a second layer is deposited on the first layer. An active layer is deposited on the second layer. Found out is such a growth rate of an InP layer as to cause the photoluminescence intensity of a layer corresponding to the active layer to be one tenth as small as that when the InP layer is deposited at a growth rate of 0.2 microns per hour in the case where the InP layer deposition is carried out instead of the first layer deposition under the conditions wherein the ratio of the flow rate of the source material of P to the total flow rate of the carrier gas and the substrate temperature are the same as those in the first layer deposition but the growth rate of the InP layer is different from that of the first layer. The growth rate of the first layer is lower than such a growth rate of the InP layer as to cause the photoluminescence intensity to be one tenth. Accordingly, a diffraction grating can be formed with excellent reproductiveness and high accuracy, moreover, a high quality semiconductor layer can be deposited on thus formed diffraction grating.

Manufacturing method of a semiconductor device having a diffraction grating

A distribution feedback laser diode, comprises a substrate, a waveguide layer provided on the substrate, an active layer provided on the waveguide layer, a diffraction grating provided at an interface between the substrate and the waveguide layer for reflecting an optical radiation formed in the active layer back and forth, a clad layer provided on the active layer for confining the optical radiation within the active layer, a plurality of segmented electrodes provided on the top surface of the clad layer along an elongated direction of the laser diode for injecting the carriers into the active layer, wherein at least one of the segmented electrodes is provided in correspondence to a part of the active layer in which the optical radiation formed in the active layer has a maximum intensity level, and a backside electrode provided at the bottom surface of the substrate for injecting the carriers into the active layer through the substrate.

Method of making a tunable laser diode having a distributed feedback

A driver circuit of a laser diode. The laser diode has a first electrode structure for injecting a first drive current with a first magnitude and a second electrode structure separated from the first electrode structure for injecting a second drive current with a second magnitude. The second electrode structure is provided in correspondence to a location in diode at which said carriers are depleted most. The driver circuit comprises a presetting circuit for presetting a relationship between the first and second magnitudes, and a current distribution circuit controlled by the presetting circuit for producing the first and second drive currents with respective magnitude satisfying the relationship that is preset by the presetting means.

Driver circuit of a tunable laser diode

A distribution feedback laser diode comprises a substrate, a waveguide layer provided on the substrate, an active layer provided on the waveguide layer, a diffraction grating provided at an interface between the substrate and the waveguide layer for reflecting an optical radiation formed in the active layer back and forth, a clad layer provided on the active layer for confining the optical radiation within the active layer, and a plurality of segmented electrodes provided on the top surface of the clad layer along an elongated direction of the laser diode for injecting the carriers into the active layer in dependence upon a modulation signal. At least one of the segmented electrodes is provided in correspondence to a part of the active layer in which the optical radiation formed in the active layer has a maximum intensity level, thereby enabling selective injection of carriers at that part of the active layer.

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Kawasaki, Japan

Yuji Kotaki