A tunable laser that includes an array of parallel optical amplifiers is described. The laser may also include an intracavity NM coupler that couples power between a cavity mirror and the array of parallel optical amplifiers. Phase adjusters in optical paths between the NM coupler and the optical amplifiers can be used to adjust an amount of power output from M-1 ports of the NM coupler. A tunable wavelength filter is incorporated in the laser cavity to select a lasing wavelength.

A tunable laser that includes an array of parallel optical amplifiers is described. The laser may also include an intracavity NM coupler that couples power between a cavity mirror and the array of parallel optical amplifiers. Phase adjusters in optical paths between the NM coupler and the optical amplifiers can be used to adjust an amount of power output from M1 ports of the NM coupler. A tunable wavelength filter is incorporated in the laser cavity to select a lasing wavelength.

Single-mode quantum cascade semiconductor lasers are provided. The lasers comprise a laser element, the laser element comprising a quantum cascade active layer; an upper cladding layer over the quantum cascade active layer; and a lower cladding layer under the quantum cascade active layer, wherein the quantum cascade active layer, the upper cladding layer and the lower cladding layer define a guided optical mode. The quantum cascade active layer and the upper and lower cladding layers are shaped in the form of a ridge structure having a front face, a back face opposite the front face, and a lasing face through which laser emission exits the ridge structure, the ridge structure configured such that the laser emission has a single-lobe, far-field beam pattern from the ridge structure comprising certain sections, including tapered sections, collateral sections, or both.

In one embodiment, a distributed feedback laser includes a laser comprising a waveguide, the waveguide having a variable width from a first end to a second end, the laser to generate optical energy of a plurality of lasing wavelengths. Other embodiments are described and claimed.

In one embodiment, a distributed feedback laser includes a laser comprising a waveguide, the waveguide having a variable width from a first end to a second end, the laser to generate optical energy of a plurality of lasing wavelengths. Other embodiments are described and claimed.