Hideyuki Hosoya

Low-loss optical waveguides written by femtosecond laser pulses for three-dimensional photonic devices

Femtosecond laser microfabrication attracts much attention due to its ability to write three-dimensional photonic devices into various transparent materials. By optimizing laser processing parameters and annealing at high temperature, low-loss straight optical waveguides are written in a pure silica glass. The minimum propagation-loss is 0.05 dB/cm at the wavelength of 1550 nm. The utility of the femtosecond laser processing is demonstrated by writing a low-loss three-dimensional 1×8 optical splitter.

Low insertion-loss and high isolation polymeric Y-branching thermo-optic switch with partitioned heater

A thermo-optic switch with low insertion-loss and high isolation was realized using a polymeric Y-branching waveguide. The partitioned heater greatly improves the isolation. Over 40dB isolation was achieved with the low insertion loss of 1.8dB.

Transient performance of ultra-fast AGC-EDFA in 40-channel add/drop operation

We have achieved a good gain transient performance of an ultra-fast AGC-EDFA in 40-channel add/drop operation owing to the combination of an electrically controlled pump LD and a high-speed VOA.

Improvement on asymmetry of low-loss waveguides written in pure silica glass by femtosecond laser pulses

Low-loss and symmetrical mode-field optical waveguides were directly written in a pure silica glass by nearinfrared femtosecond laser processing. By optimizing laser processing parameters, such as the pulse duration and the pulse energy of femtosecond laser pulses, we demonstrated the propagation-loss reduction and the mode- field diameter (MFD) aspect ratio improvement. We have achieved the propagation-loss of 0.10 dB/cm and the MFD aspect ratio of 1.0 at the wavelength of 1550 nm at the same time.

Ultra low-loss waveguides of 0.12 dB/cm directly written in pure silica glass by femtosecond laser pulses

Ultra low-loss of 0.12 dB/cm at 1580 nm was achieved for directly written waveguides in pure silica glass using femto-second laser for the first time as far as we know. A three-dimensionally structured optical splitter was also demonstrated.