Fabrication of coupled mode photonic devices in glass by nonlinear femtosecond laser materials processing

Coupled mode devices are fabricated in transparent glasses by nonlinear materials processing with femtosecond laser pulses. Using the direct output of an extended cavity femtosecond laser, without the need for a laser amplifier, single mode waveguides can be rapidly fabricated with well controlled parameters. A variety of photonic waveguide devices are demonstrated. Directional couplers with various interaction lengths and coupling coefficients are fabricated and their coupling properties are characterized. Measurements demonstrate coupled mode behavior consistent with theory. An unbalanced Mach-Zehnder interferometer is also fabricated and demonstrated as a spectral filter.