Single longitudinal mode laser diode
View Patent ↗A single-mode, etched facet distributed Bragg reflector laser includes an AlGaInAs/InP laser cavity, a front mirror stack with multiple Fabry-Perot elements, a rear DBR reflector, and a rear detector. The front mirror stack elements and the rear reflector elements include input and output etched facets, and the laser cavity is an etched ridge cavity, all formed from an epitaxial wafer by a two-step lithography and CAIBE process.
1. A lithographically formed stacked Fabry-Perot optical waveguide filter for laser light having a wavelength λ, said filter being formed on an epitaxial semiconductor wafer and comprising multiple Fabry-Perot optical waveguide filter elements, each being separated from one another by a corresponding one of multiple gap elements, each of said gap elements having a length of mλ/2±λ/10, where m is a positive integer and is selected so that a gap element has an effective reflectivity of no more than 0.2.
2. The lithographically formed stacked Fabry-Perot wave-guide filter of claim 1 , wherein each of said filter elements has the same length.
3. A semiconductor diode laser, comprising:
a laser waveguide lithographically formed on an epitaxial semiconductor wafer, said laser waveguide having an axis;
a lithographically formed stacked Fabry-Perot optical filter on said axis, said filter being integrally formed on said epitaxial semiconductor wafer on a front end of said laser waveguide and comprising multiple Fabry-Perot optical waveguide filter elements, each being separated from one another by a corresponding one of multiple gap elements, each of said gap elements having a length which is substantially a multiple of the half-wavelength of light within said gap elements and a gap element has an effective reflectivity of no more than 0.2.
4. The semiconductor diode laser of claim 3 , wherein each of said filter elements has a length in the range of 2-10 μm.
5. The semiconductor diode laser of claim 3 , further including a high DBR reflector element at a rear end of said waveguide.
6. The semiconductor diode laser of claim 5 , wherein said rear high DBR reflector includes a reflector dip which coincides with a neighboring reflection peak for said stacked Fabry-Perot filters.
7. The semiconductor diode laser of claim 5 , wherein each of said Fabry-Perot optical waveguide filter elements has a thickness that is twice as large as a thickness of said high DBR reflector element.
8. The semiconductor diode laser of claim 4 , wherein each of said gap elements has a length that is smaller than the length of said filter elements.
9. The lithographically formed stacked Fabry-Perot wave-guide filter of claim 1 , wherein each of said filter elements has a length in the range of 2-10 μm.
10. The lithographically formed stacked Fabry-Perot wave-guide filter of claim 9 , wherein each of said gap elements has a length that is smaller than the length of said filter elements.
11. The lithographically formed stacked Fabry-Perot wave-guide filter of claim 1 , wherein m is selected to be 2.