Multi-level integrated photonic devices
View Patent ↗A laser and electroabsorption modulator (EAM) are monolithically integrated through an etched facet process. Epitaxial layers on a wafer include a first layer for a laser structure and a second layer for an EAM structure. Strong optical coupling between the laser and the EAM is realized by using two 45-degree turning mirrors to route light vertically from the laser waveguide to the EAM waveguide. A directional angled etch process is used to form the two angled facets.
1. An integrated photonic device comprising:
a substrate having a surface x-y plane and a height z;
at least first and second epitaxial layers on said substrate;
at least a first etched-facet device fabricated in said first epitaxial layer;
at least a second etched-facet device fabricated in said second epitaxial layer; wherein the etched facets of the first and second devices optically connect said first device with said second device; and
a trench passing downwardly at an angle other than 90 degrees to the surface x-y plane of the substrate in both the x and y directions, passing underneath said second etched-facet device and forming an etched facet of said first etched-facet device.
2. The device of claim 1 , wherein said second etched-facet device is a laser.
3. The device of claim 2 , wherein at least a first etched-facet is above the critical angle.
4. The device of claim 3 , wherein said first etched-facet is at an angle of about 45-degrees.
5. The device of claim 4 , wherein said first etched-facet causes light generated in an active region in said laser to be emitted in a direction that is substantially perpendicular with respect to said substrate.
6. The device of claim 5 , wherein said first device is an EAM.
7. The device of claim 6 , wherein said first etched-facet and at least a second etched-facet are vertically aligned, whereby light generated in an active region in said laser is reflected by said first and second etched-facets and directed to said EAM.
8. The device of claim 7 , wherein said first and second etched-facets lie in parallel, spaced apart planes angled with respect to x, y and z axes of said substrate.
9. The device of claim 8 , wherein said planes intersect the x-z plane forming lines that are at about 45 degree angles with respect to said x and z axes.