Multi-Fiber Section Tunable Optical Filter

A tunable optical filter comprising:

• an end section of a first single-mode optical fiber having an end surface;
• an end section of a second single-mode optical fiber longitudinally aligned with said first single-mode optical fiber end section, said second single-mode optical fiber end section having an end surface facing said end surface of said first single-mode optical fiber end section;
• PMN-PT ((1-x)Pb (Mg⅓ Nb⅔) O3-x—Pb Ti O3)) piezoelectric material controlling the separation between said first single-mode optical fiber end section and said second single-mode optical fiber end section and selecting wavelengths of optical signals carried through said end sections of said first and second single-mode optical fibers;
• and
• a collimating section of a multimode, graded index optical fiber attached to at least one of said single-mode optical fiber end sections, said collimating multimode, graded index optical fiber section having a first end surface angled from a perpendicular plane to a longitudinal axis common to said at least one single-mode optical fiber end section and said collimating multimode, graded index optical fiber section and joined to said end surface of said at least one single-mode optical fiber end section, said end surface of said at least one single-mode optical fiber end section reciprocally angled to said first end surface of said collimating multimode, graded index optical fiber section.