Nippon Electric Co., Ltd.

Roy Lang

Masayasu Ueno

Kohroh Kobayashi

Hiroo Yonezu

Izuo Hayashi

A stripe-shaped excitation region is provided in an active layer of a double heterojunction laser device, the excitation region and the other region of the active layer being endowed with an effective refractive index difference or optical absorption coefficient difference therebetween, and a carrier injection region is provided contiguously to the excitation region, whereby the laser device exhibits a low ohmic resistance, effects a stable lower-order transverse mode oscillation and suppresses relaxation oscillations. By preventing the stripe-shaped excitation region and the carrier injection region from being exposed to reflective surfaces, the aforecited beneficial results can be realized over a wide range of operating currents, and a laser device of extremely high power density emission is achieved due to the increase of the threshold of the catastrophic optical damage on mirrors.

Stripe-geometry double heterojunction laser device

In an active layer restricted by a pair of heterojunctions in a semiconductor laser, a stripe region and a contiguous region are made to have a difference in kinds and/or concentrations of impurity to give the stripe region a higher dielectric constant, preferably by about 0.01-1%, than the contiguous region whereby transverse laser oscillation confined to the active layer by the heterojunctions is further confined to the stripe region in a width direction parallel to the heterojunctions. The dielectric constant profile established in the active layer stabilizes the transverse mode and eliminates nonlinearities in the laser output - exciting current curve as well as other undesirable performance characteristics that are exhibited in conventional stripe-geometry lasers. The difference in the impurity gives the stripe region a narrower band gap of from about 5 to about 100 meV than the contiguous region. For a laser of III-V-Group semiconductor materials, the difference is achieved by doping these regions with an n-type and/or a p-type impurity. The stripe width may be between about 1 micron and several tens of microns. The laser stably produces a single-mode optical output of 10 and 30 mW or more in CW and pulsed operation, respectively.

Heterostructure laser having a stripe region defined in an active layer

A semiconductor laser device in which a part of the laser output is reflected from an external reflector and injected into the laser element with a delay that is less than the relaxation oscillation period of the laser pulse output.

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Tokyo, Japan

Roy Lang