Ryan Imansyah

Electrically controlled optical-mode switch for fundamental mode and first order mode

We have proposed an optical mode switch, the principle of which is based on the partial phase shift of injected light; therefore, one important issue is to clarify the proper design criteria for the mode combiner section. We focused on the bending radius of the S-bend waveguide issue that is connected to the multi mode waveguide in the Y-junction section that acts as mode combiner. Long radius leads to undesired mode coupling before the Y-junction section, whereas a short radius causes radiation loss. Thus, we simulated this mode combiner by the beam-propagation method to obtain the proper radius. In addition, we used a trench pin structure to simplify the fabrication process into a single-step dry-etching process. As a result, we successfully fabricated an optical-mode switch with the bending radius R = 610 µm. It showed the successful electrical mode switching and the achieved mode crosstalk was approximately −10 dB for 1550 nm wavelength with the injection current of 60 mA (5.7 V).

Mode crosstalk evaluation on optical mode switch

We show the mode crosstalk between the fundamental mode and the 1st order mode based on the optical mode switch to investigate the performance experimentally for the first time. In order to evaluate the mode crosstalk, we fabricated and integrated multimode interference (MMI) mode filter with the optical mode switch. The crosstalk of approximately -10 dB between modes has been evaluated by using this mode filter.

First demonstration of electrically controlled mode switching

Electrically controlled mode switching is demonstrated for the first time. PIN structure was realized by using trench in the lateral direction. As a result, mode-switchmg with the injection current of 60mA (5. 7V) was successfully achieved with mode-crosstalk of 10dB at λ = 1550nm for the both TE and TM modes.

Single-step dry-etched lateral PIN by using trench structure for optical mode switch

Trench structure that enables lateral PIN with single-step dry-etching was exploited to optical mode switch for the first time. Successful current-injected (60mA) optical mode switching was confirmed with polarization independent characteristics.