| dc.description.abstract | In this study, we propose the liquid crystal infiltrated waveguide with distributed Bragg reflector (DBR), which enables a dynamic control of tunable waveguide. The reorientation of the high susceptibility of liquid crystal (LC) molecular is successively achieved by varying external voltage to change the refractive index of the guiding core. Due to the electrical tuning of LC and the wavelength-selective property of DBR structure, the waveguide can be used as the tunable switching or the filter device.
In the cladding of DBR structure, the multilayer stacks are formed by six pairs of Si3N4/SiO2, which is designed by the transfer matrix method. Also, we use the beam propagation method (BPM) to simulate the light behavior for different indices of LC in the guiding core.
In experimental parts, we utilize three approaches to realize the characteristics of LC infiltrated waveguide with DBR. First of all, we use the polarized optical microscopy to observe and speculate the alignment of LC. Secondly, in the measurement of waveguide with different applied voltages, which is operating at 532nm, the waveguide can be served as an electrically optical switch with 28dB attenuation at 9Vrms. Finally, we measure the transmission spectrum of waveguides at visible wavelength range for varying applied voltages. The result shows that the LC in guiding core can change the transmission spectrum of the LC-filled waveguide. In the voltage-off state, the wavelength from 500nm to 660nm can be confined in the guiding core. As the applied voltage increases, the bandgap edge can be shift to the short wavelength. Specifically, while the external voltage is from 9Vrms to 20Vrms, the propagated light cannot be confined in the guiding core. At the external voltage of 30Vrms, we measured the all of visible wavelength that can be confined in the guiding core.
The results of our simulation and the experiment measurement can help us to design and fabricate tunable devices based on the liquid crystal infiltrated waveguide with DBR.
| en_US |