Tapered waveguide high-power quantum cascade lasers

摘要

An improved quantum cascade laser, the improvement comprising a longitudinally non-uniform dielectric waveguide. The waveguide includes a longitudinally straight section and a longitudinally tapered section. The length of the tapered section is between 5% and 50% of the total cavity length. The tapered section tapers at a taper angle from the facet width to the ridge width. The taper angle is smaller than the delineation angle of the waveguide.

主权项

1. An improved quantum cascade laser, the improvement comprising a non-uniform dielectric waveguide, the dielectric waveguide comprising:
(a) a longitudinally straight section having a first end, a second end, a ridge width, and a length; and (b) a longitudinally tapered section at the second end of the straight section, the tapered section having a first end and a second end, the first end of the tapered section being connected to the second end of the straight section, the tapered section having a length, the tapered section tapering at a taper angle from a facet width of the tapered section at the second end of the tapered section to the ridge width at the first end of the tapered section, the taper angle being less than a delineation angle of the dielectric waveguide; and (c) wherein the delineation angle being given by the equation:Ωd=wt4⁢⁢λ⁢neff2-nclad2ncorewhere w and t are the width and a thickness of the dielectric waveguide, respectively, λ is a radiation wavelength, ncore is a core refractive index, nclad is a cladding refractive index, and neff is an effective refractive index of a waveguide mode.