Fuji Photo Film Company, Limited

Fujio Akinaga

Toshiaki Fukunaga

Mitsugu Wada

In a semiconductor laser element: a lower cladding layer of a first conductive type, a lower optical waveguide layer made of InGaP which is undoped or the first conductive type, an active layer made of InGaAsPlattice-matching with GaAs (0&#x3c;x3&#x2266;0.3 and 0&#x2266;y3&#x2266;0.5), an upper optical waveguide layer made of InGaP which is undoped or a second conductive type, and a first upper cladding layer of the second conductive type are formed in this order above the substrate. The lower optical waveguide layer has a bandgap which gradually decreases with elevation within the lower optical waveguide layer, and the upper optical waveguide layer has a bandgap which gradually increases with elevation within the upper optical waveguide layer.

Semiconductor laser element including optical waveguide layers which have gradually varying bandgaps so as to reduce electrical resistance at interfaces

In a semiconductor laser device, a lower cladding layer, a lower optical waveguide layer, an active layer, an upper optical waveguide layer, an upper cladding layer, and a contact layer are formed in this order on a GaAs substrate. The semiconductor laser device has at least one of first and second resistance reduction layers. The first resistance reduction layer is arranged between the substrate and the lower cladding layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the substrate, and smaller than the energy gap of the lower cladding layer. The second resistance reduction layer is arranged between the upper cladding layer and the contact layer, and made of an InGaAsP material having an energy gap which is greater than the energy gap of the contact layer, and smaller than the energy gap of the upper cladding layer.

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Kaisei-machi, Japan

Fujio Akinaga