Tunable optical add/drop multiplexer
View Patent ↗The tunable add/drop multiplexer including a tiltable mirror, a fixed thin film filter, and first and second retro-reflector elements for redirecting express channels back out an input/output port and for redirecting drop channels back out an add/drop port, respectively.
1. An optical retro-reflector comprising:
an input port for launching an input beam of light;
a tiltable mirror pivotable about a rotation axis for redirecting the input beam; and
first, second and third fixed mirrors;
wherein said first and second fixed mirrors are optically aligned with said tiltable mirror, such that the input beam reflected from the tiltable mirror a first time is redirected back to the tiltable mirror a second time, which reflects the beam towards and normal to said third fixed mirror;
wherein the input beam travels a path in a first plane from the input port to the third fixed mirror; and
wherein said third fixed mirror reflects the input beam back to the tiltable mirror a third time, the first and second fixed mirrors, and to the tiltable mirror a fourth time.
2. The optical retro-reflector according to claim 1 , wherein said third fixed mirror is a vertically displaced retro-reflector comprising two substantially perpendicular reflective surfaces for directing the input beam back in a second plane parallel to the first plane to a second input/output port.
3. The optical retro-reflector according to claim 1 , wherein said second and third fixed mirrors are comprised of a contiguous mirrored surface in a same plane.
4. The optical retro-reflector according to claim 1 , wherein said first, second and third fixed mirrors are comprised of perpendicular surfaces of a same block of material.