Variable-wavelength semiconductor laser and gas sensor using same

A tunable wavelength semiconductor laser comprising:

• an n-type semiconductor substrate;
• an active layer which is disposed above the n-type semiconductor substrate and which generates light;
• a p-type cladding layer disposed above the active layer;
• and
• wavelength selecting means for causing to selectively oscillate only a specific wavelength from the light generated in the active layer,
• the tunable wavelength semiconductor laser capable of oscillating at the specific wavelength being performed by injecting current into the active layer, and the specific wavelength being varied by changing the magnitude of the current, wherein
• a width of the active layer orthogonal to a propagation direction of the light generated in the active layer, and showing a length in a direction parallel to the n-type semiconductor substrate is about 1 μm to 2 μm, and
• the p-type cladding layer includes a lightly doped cladding layer having a low impurity concentration and a heavily doped cladding layer having a high impurity concentration which are sequentially arranged from the active layer side.

A tunable wavelength semiconductor laser comprising:

• an n-type semiconductor substrate;
• an active layer which is disposed above the n-type semiconductor substrate and which generates light;
• a p-type cladding layer disposed above the active layer;
• and
• wavelength selecting means for causing to selectively oscillate only a specific wavelength from the light generated in the active layer,
• the tunable wavelength semiconductor laser capable of oscillating at the specific wavelength being performed by injecting current into the active layer, and the specific wavelength being varied by changing the magnitude of the current, wherein
• a device length showing a length in a propagation direction of the light generated in the active layer is about 200 μm to 500 μm,
• a width of the active layer orthogonal to the propagation direction of the light generated in the active layer, and showing a length in a direction parallel to the substrate is about 1 μm to 2 μm, and
• the p-type cladding layer includes a lightly doped cladding layer having a low impurity concentration and a heavily doped cladding layer having a high impurity concentration which are sequentially arranged from the active layer side.

A gas detector comprising:

• a semiconductor laser module having a tunable wavelength semiconductor laser incorporated therein, the semiconductor laser module emitting laser light modulated in wavelength at a specified frequency;
• a photoreceiver which receives laser light to convert into an electrical signal, the laser light being emitted from the semiconductor laser module and having passed through a gas to be measured;
• and
• a gas detection unit which detects the gas to be measured on the basis of the electrical signal output from the photoreceiver,
• the tunable wavelength semiconductor laser incorporated in the semiconductor laser module comprising:
• an n-type semiconductor substrate;
• an active layer which is disposed above the n-type semiconductor substrate and which generates light;
• a p-type cladding layer disposed above the active layer;
• and
• wavelength selecting means for causing to selectively oscillate only a specific wavelength from the light generated in the active layer,
• the tunable wavelength semiconductor laser capable of oscillating at the specific wavelength being performed by injecting current into the active layer, and the specific wavelength being varied by changing the magnitude of the current, wherein
• a device length showing a length in a propagation direction of the light generated in the active layer is about 200 μm to 500 μm, and
• the p-type cladding layer includes a lightly doped cladding layer having a low impurity concentration and a heavily doped cladding layer having a high impurity concentration which are sequentially arranged from the active layer side.

A gas detector comprising:

• a semiconductor laser module having a tunable wavelength semiconductor laser incorporated therein, the semiconductor laser module emitting laser light modulated in wavelength at a specified frequency;
• a photoreceiver which receives laser light to convert into an electrical signal, the laser light being emitted from the semiconductor laser module and having passed through a gas to be measured;
• and
• a gas detection unit which detects the gas to be measured on the basis of the electrical signal output from the photoreceiver,
• the tunable wavelength semiconductor laser incorporated in the semiconductor laser module comprising:
• an n-type semiconductor substrate;
• an active layer which is disposed above the n-type semiconductor substrate and which generates light;
• a p-type cladding layer disposed above the active layer;
• and
• wavelength selecting means for causing to selectively oscillate only a specific wavelength from the light generated in the active layer,
• the tunable wavelength semiconductor laser capable of oscillating at the specific wavelength being performed by injecting current into the active layer, and the specific wavelength being varied by changing the magnitude of the current, wherein
• a width of the active layer orthogonal to a propagation direction of the light generated in the active layer, and showing a length in a direction parallel to the n-type semiconductor substrate is about 1 μm to 2 μm, and
• the p-type cladding layer includes a lightly doped cladding layer having a low impurity concentration and a heavily doped cladding layer having a high impurity concentration which are sequentially arranged from the active layer side.

A gas detector comprising:

• a semiconductor laser module having a tunable wavelength semiconductor laser incorporated therein, the semiconductor laser module emitting laser light modulated in wavelength at a specified frequency;
• a photoreceiver which receives laser light to convert into an electrical signal, the laser light being emitted from the semiconductor laser module and having passed through a gas to be measured;
• and
• a gas detection unit which detects the gas to be measured on the basis of the electrical signal output from the photoreceiver,
• the tunable wavelength semiconductor laser incorporated in the semiconductor laser module comprising:
• an n-type semiconductor substrate;
• an active layer which is disposed above the n-type semiconductor substrate and which generates light;
• a p-type cladding layer disposed above the active layer;
• and
• wavelength selecting means for causing to selectively oscillate only a specific wavelength from the light generated in the active layer,
• the tunable wavelength semiconductor laser capable of oscillating at the specific wavelength being performed by injecting current into the active layer, and the specific wavelength being varied by changing the magnitude of the current, wherein
• a device length showing a length in a propagation direction of the light generated in the active layer is about 200 μm to 500 μm,
• a width of the active layer orthogonal to the propagation direction of the light generated in the active layer, and showing a length in a direction parallel to the substrate is about 1 μm to 2 μm, and
• the p-type cladding layer includes a lightly doped cladding layer having a low impurity concentration and a heavily doped cladding layer having a high impurity concentration which are sequentially arranged from the active layer side.