16:15 〜 16:30
▼ [21p-224A-12] Proposal of new modulation schemes of the propagating light in plasmonic SI MZI
キーワード：MZI, Plasmonics, Au
Introduction
Currently, in most plasmonic Mach-Zehnder Interferometers (MZI) where plasmonic metal structures such as gratings, slit-hole structures or other are used, measured signals are transmitting horizontally through the waveguide and the transmitted signals are then modulated.[1-3] In this work, we propose a novel SI MZI with an interaction of surface plasmonic wave.
Device structure and analytic results
The proposed device is schematically shown in Fig. 1 (a) a plane view of the whole MZI and (b) a cross section of the modulation region. In the modulation region, it is equipped with an asymmetric Au grating to an Au film on the top where a signal light is propagating through a Si core and is modulated with the help of excited surface wave. With this element being under plasmonic (SPR)-wavelength external excitation (l=550nm) a clear image of energy flow difference between to the left and right sides is seen compared to a symmetric structure, as shown in Fig. 2. By placing the elements in the MZI in the modulation region and exciting them with the same excitation wavelength as the input signal an 8% difference of the output signal compared with the case under no excitation modulation was seen as shown in Fig 3 for the long wavelength range. It is expected that since the flow difference from up to the sides show the difference in plasmonic regions the characteristics for those wavelengths would give also a difference. Additionally, the device shows to be dependent on the refractive index of surrounding medium. Thus this device can be used as a refractive index sensor for surrounding media while under excitation. All simulations were done with Comsol 5.3a RF module.
Acknowledgments
The authors appreciate the permission to use of Comsol in University of Tartu.
Currently, in most plasmonic Mach-Zehnder Interferometers (MZI) where plasmonic metal structures such as gratings, slit-hole structures or other are used, measured signals are transmitting horizontally through the waveguide and the transmitted signals are then modulated.[1-3] In this work, we propose a novel SI MZI with an interaction of surface plasmonic wave.
Device structure and analytic results
The proposed device is schematically shown in Fig. 1 (a) a plane view of the whole MZI and (b) a cross section of the modulation region. In the modulation region, it is equipped with an asymmetric Au grating to an Au film on the top where a signal light is propagating through a Si core and is modulated with the help of excited surface wave. With this element being under plasmonic (SPR)-wavelength external excitation (l=550nm) a clear image of energy flow difference between to the left and right sides is seen compared to a symmetric structure, as shown in Fig. 2. By placing the elements in the MZI in the modulation region and exciting them with the same excitation wavelength as the input signal an 8% difference of the output signal compared with the case under no excitation modulation was seen as shown in Fig 3 for the long wavelength range. It is expected that since the flow difference from up to the sides show the difference in plasmonic regions the characteristics for those wavelengths would give also a difference. Additionally, the device shows to be dependent on the refractive index of surrounding medium. Thus this device can be used as a refractive index sensor for surrounding media while under excitation. All simulations were done with Comsol 5.3a RF module.
Acknowledgments
The authors appreciate the permission to use of Comsol in University of Tartu.