Abstract: A laser module includes a semiconductor laser element and a feedback optical component forming an external cavity with the semiconductor laser element. Even if a ratio of a current threshold of the laser module changing according to a polarized state of returned light from the feedback optical component to a current threshold of the semiconductor laser element is in an arbitrary range within a predetermined range, a total value of a relative intensity noise occurring between a first frequency determined according to a cavity length of the external cavity and at least equal to or more than a frequency band of using a laser light and a second frequency calculated by multiplying the first frequency by a predetermined number is equal to or more than ?40 dB.

Abstract: A laser module includes a semiconductor laser element and a feedback optical component forming an external cavity with the semiconductor laser element. Even if a ratio of a current threshold of the laser module changing according to a polarized state of returned light from the feedback optical component to a current threshold of the semiconductor laser element is in an arbitrary range within a predetermined range, a total value of a relative intensity noise occurring between a first frequency determined according to a cavity length of the external cavity and at least equal to or more than a frequency band of using a laser light and a second frequency calculated by multiplying the first frequency by a predetermined number is equal to or more than ?40 dB.

Abstract: A semiconductor laser device emitting a laser beam having stable emitting wavelength and a multimode spectrum is provided. The semiconductor laser device is a Fabry-Perot type semiconductor laser device having a layer structure including an active layer of a quantum well structure, and emitting a laser beam having wavelength stabilized by an action of return light and having a multimode spectrum, wherein each well layer satisfies relation: ?/d?1.3×10?3 nm?1 where ? and d(nm) are an optical confinement factor and a thickness of a well layer, respectively.

Abstract: A semiconductor laser device comprises first current blocking layers formed to define a stripe-shaped current injected region extending in the direction in a front facet from which a laser light is emitted and a rear facet opposing thereto are connected, and a second current blocking layer formed to transverse the stripe-shaped current injected region in the vicinity of the front facet. The first current blocking layers and the second current blocking layer are made of the same layer. Accordingly, a current blocking structure is provided in the vicinity of the facet with the structure which is easily formed, causes no damage on the semiconductor laser device, and minimizes the property degradation, thereby a high facet COD level and high reliability in long-term continuous operations can be achieved.

Abstract: A semiconductor laser device emitting a laser beam having stable emitting wavelength and a multimode spectrum is provided.

Abstract: A real index guided semiconductor laser device includes an optical waveguide layer at least on one side of an active layer that has a band gap energy not less than that of the active layer; a cladding layer on an outer side of the optical waveguide layer that has a band gap energy not less than that of the optical waveguide layer; a refractive index control layer having a striped window, buried in the optical waveguide layer by selective growth; and a semiconductor layer formed in the optical waveguide layer by selective growth prior to the selective growth of the refractive index control layer. In a laminated portion including the semiconductor layer and the refractive index control layer, a change in effective refractive index due to a change in thickness of the semiconductor layer is smaller than that of the refractive index control layer.

Abstract: On a substrate of n-type GaAs are sequentially formed an n-type cladding layer (AlGaAs, Al content x=0.07, thickness t=2.86 &mgr;m), an n-type optical waveguide layer (GaAs, t=0.49 &mgr;m), an n-type carrier blocking layer (AlGaAs, x=0.40, t=0.03 &mgr;m), an active layer (composed of an In0.18Ga0.82As quantum well layer and a GaAs barrier layer), a p-type carrier blocking layer (AlGaAs, x=0.40, t=0.03 &mgr;m), a p-type optical waveguide layer (GaAs, t=0.49 &mgr;m), a p-type cladding layer (AlGaAs, x=0.20, t=1.08 &mgr;m), and a p-type cap layer (GaAs) in which a pair of n-type current blocking layers (GaAs) are buried. With this construction, the occurrence of a wavelength spit due to a higher-order mode can be inhibited thereby stabilizing a higher power operation.

Abstract: A real index guided semiconductor laser device includes an optical waveguide layer at least on one side of an active layer that has a band gap energy not less than that of the active layer; a cladding layer on an outer side of the optical waveguide layer that has a band gap energy not less than that of the optical waveguide layer; a refractive index control layer having a striped window, buried in the optical waveguide layer by selective growth; and a semiconductor layer formed in the optical waveguide layer by selective growth prior to the selective growth of the refractive index control layer. In a laminated portion including the semiconductor layer and the refractive index control layer, a change in effective refractive index due to a change in thickness of the semiconductor layer is smaller than that of the refractive index control layer.

Abstract: A semiconductor laser device comprises first current blocking layers formed to define a stripe-shaped current injected region extending in the direction in a front facet from which a laser light is emitted and a rear facet opposing thereto are connected, and a second current blocking layer formed to transverse the stripe-shaped current injected region in the vicinity of the front facet. The first current blocking layers and the second current blocking layer are made of the same layer.

Abstract: A piezoelectric unit is composed of a plurality of piezoelectric elements. In one embodiment, a first driving electrode is provided over the whole surface of the lower surface of the piezoelectric element. A second driving electrode is provided over the whole surface between the piezoelectric elements. The driving electrodes are connected to a driving signal source. Detection electrodes are provided on the upper surface of the piezoelectric element. At least one of the detection electrodes is connected to one of the output terminals and at least another of the detection electrodes is connected to the other of the output electrodes. One piezoelectric element is polarized upward and another piezoelectric element is polarized downward. A vertical 1st order vibration is driven in a longitudinal direction and a 2nd order bending vibration is detected by the detection electrodes, and a voltage proportional to a coriolis force (rotational angular velocity) is outputted.