InAs quantum-dot lasers that feature distributed feedback and lateral evanescent-wave coupling have been demonstrated in operation at a wavelength of 1.3 µm. These lasers are prototypes of optical-communication oscillators that are required to be capable of stable single-frequency, single-spatial-mode operation.

A Laterally Coupled Quantum-Dot Distributed-Feedback Laser contains structures that favor oscillation at a single frequency in a single spatial mode.

A laser of this type (see figure) includes an active layer that comprises multiple stacks of InAs quantum dots embedded within InGaAs quantum wells. Distributed feedback is provided by gratings formed on both sides of a ridge by electron lithography and reactive-ion etching on the surfaces of an AlGaAs/GaAs waveguide. The lateral evanescent-wave coupling between the gratings and the wave propagating in the waveguide is strong enough to ensure operation at a single frequency, and the waveguide is thick enough to sustain a stable single spatial mode.

In tests, the lasers were found to emit continuous-wave radiation at temperatures up to about 90 °C. Side modes were found to be suppressed by more than 30 dB.

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Refer to NPO-30503, volume and number of this NASA Tech Briefs issue, and the page number.