Abstract: An optical module including a temperature measurement module and an optical part having a temperature dependency. The module includes a temperature control part mounted directly or indirectly on the optical part and the temperature measurement part for controlling a temperature of the optical part and the measurement part by thermal contact. An adjustment system is also provided for adjusting a difference of the temperature of the optical part and the measurement part by controlling the heat flow into/out of the optical part or the measurement part.

Abstract: A thermoelectric module comprises an upper insulating substrate and a lower insulating substrate; an upper electric circuit metal layer and a lower electric circuit metal layer bonded respectively to the surfaces of said insulating substrates which are positioned face to face; an upper blast stopper layer and a lower blast stopper layer fabricated respectively on said electric circuit metal layers; an upper bonding layer and a lower bonding layer fabricated respectively on said blast stopper layers; and a plurality of -shaped elements consisting of a pair of the P-type semiconductor element and N-type semiconductor element which are fabricated between said upper and lower bonding layers and are electrically connected in series through said upper and lower blast stopper layers.

Abstract: An optical module including a temperature measurement module and an optical part having a temperature dependency. The module includes a temperature control part mounted directly or indirectly on the optical part and the temperature measurement part for controlling a temperature of the optical part and the measurement part by thermal contact. An adjustment system is also provided for adjusting a difference of the temperature of the optical part and the measurement part by controlling the heat flow into/out of the optical part or the measurement part.

Abstract: A temperature adjustment device has a first thermoelectric cooling module, a second thermoelectric cooling module on which the first thermoelectric cooling module is provided, and a heat generating element which is provided on the first thermoelectric cooling module and a temperature thereof is adjusted, where assuming that a substrate area of the first thermoelectric cooling module on which the heat generating element is provided is S1(mm2) and that an amount of generated heat of the heat generating element is Qd(mW), the relationship of 20?Qd/S1?200 is met.

Abstract: A temperature adjustment device has a first thermoelectric cooling module, a second thermoelectric cooling module on which the first thermoelectric cooling module is provided, and a heat generating element which is provided on the first thermoelectric cooling module and a temperature thereof is adjusted, where assuming that a substrate area of the first thermoelectric cooling module on which the heat generating element is provided is S1 (mm2) and that an amount of generated heat of the heat generating element is Qd (mW), the relationship of 20≦Qd/S1≦200 is met.

Abstract: An optical filter is provided on a first thermo-module whose temperature is controlled to be constant, via a base. Accordingly, a wavelength discrimination characteristic of the optical filter and an optical isolator can be stabilized, thereby realizing more accurate wavelength locking. Further, a second thermo-module is provided on the first thermo-module whose temperature is controlled to be constant. Accordingly, the temperature control range of the second thermo-module can be expanded, and hence the wavelength variable range of a semiconductor laser device provided on the second thermo-module via a base and a submount can be expanded.

Abstract: An optical filter is provided on a first thermo-module whose temperature is controlled to be constant, via a base. Accordingly, a wavelength discrimination characteristic of the optical filter and an optical isolator can be stabilized, thereby realizing more accurate wavelength locking. Further, a second thermo-module is provided on the first thermo-module whose temperature is controlled to be constant. Accordingly, the temperature control range of the second thermo-module can be expanded, and hence the wavelength variable range of a semiconductor laser device provided on the second thermo-module via a base and a submount can be expanded.

Abstract: There is provide a method of manufacturing a compound semiconductor (MBE) that can make the substrate surface of the semiconductor highly clean and plane so that no impurity may be left between the substrate surface and the grown crystal layer. In the step of cleaning a substrate with MBE, the substrate surface is irradiated with V molecular beams that cannot be significantly deposited out of molecular beams to be used for the crystal growth step, said V molecular beams being irradiated under a condition of P.sub.1 .ltoreq.(P.sub.2 .times.1/2), where P.sub.1 is the pressure of V molecular beams and P.sub.2 is the pressure of molecular beams in the crystal growth step and the temperature of the substrate surface is raised by heating until stabilized group III surfaces appear on the substrate surface. A very cleanand smooth substrate surface can be obtained with such an arrangement. Harmful impurities can be completely eliminated from the interface of the substrate and the crystal.