Tunable laser, a method for making, and a method for operating such a laser

Abstract

Semiconductor lasers, in particular Quantum Cascade Lasers (QCLs) are tuable especially in the mid-IR spectral range, e.g. in wavelengths of about 3-14 μm, by precisely controlling the laser's temperature in the vicinity of the active region. The present invention introduces a novel design for locally heating the active region, thereby allowing fast heating and thus tuning a laser. It is generally applicable for lasers across the field, e.g. to QCLs with multi-color emitters or to Vertical-Cavity Single-Emitter Lasers (VCSELs) or to Distributed Feedback (DFB) lasers. Essentially, the invention consists of structurally integrating a heating resistor as part of the laser, placed close to the component to be temperature-controlled, i.e. the active region or the grating, etc., and feeding this resistor with a variable electrical current in order to locally control the thermal dissipation. In multi-emitter lasers, a resistor can be associated with each emitter section to tune the temperature of each section and thus its emitted wavelength. Similarly, in multisection DBR lasers, with a resistor associated with each grating, the latter can be tuned and thus the associated wavelength of the optical cavity. The invention also includes a novel manufacturing process, especially for buried heterostructure lasers.