Photonic device fabrication in glass by use of nonlinear materials processing with a femtosecond laser oscillator

Single-mode X couplers and three-dimensional waveguides are fabricated in transparent glasses by use of an unamplified femtosecond laser generating energies of up to 100 nJ. Changing fabrication parameters such as power and scanning speed permits creation of waveguides with a wide range of structures and refractive-index difference. Optical coherence tomography shows large refractive-index changes of up to ∼10-2 in the waveguides; these changes are consistent with guided mode analysis.