Y-junctions based on circular depressed-cladding waveguides fabricated with femtosecond pulses in Nd:YAG crystal: A route to integrate complex photonic circuits in crystals

• Published in: Optical materials Vol. 72; pp. 220 - 225
• Main Authors: Ajates, Javier G., Romero, Carolina, Castillo, Gabriel R., Chen, Feng, Vázquez de Aldana, Javier R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2017
• Subjects: Crystalline materials; Integrated photonic devices; Laser materials processing; Waveguides channeled; Crystalline materials; Waveguides channeled; Integrated photonic devices; Laser materials processing
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2017.06.014

We have designed and fabricated photonic structures such as, Y-junctions (one of the basic building blocks for construction any integrated photonic devices) and Mach-Zehnder interferometers, based on circular depressed-cladding waveguides by direct femtosecond laser irradiation in Nd:YAG crystal. The waveguides were optically characterized at 633 nm, showing nearly mono-modal behaviour for the selected waveguide radius (9 μm). The effect of the splitting angle in the Y structures was investigated finding a good preservation of the modal profiles up to more than 2°, with 1 dB of additional losses in comparison with straight waveguides. The dependence with polarization of these splitters keeps in a reasonable low level. Our designs pave the way for the fabrication of arbitrarily complex 3D photonic circuits in crystals with cladding waveguides. •Efficient Y-splitters based on circular cladding waveguides have been designed and fabricated in Nd:YAG crystal.•Nearly monomodal behaviour and low losses are reported for splitting angles of up to 2° at 633 nm.•A Mach-Zehnder interferometer has been implemented with the developed technique.•The demonstrated elements open the door to the fabrication of arbitrarily complex 3D photonic devices in crystals.