Optical Devices Based On Nanostructured Resonators Using Back Quasiphase-Matching

In this paper, nonlinear back quasiphase-matching theory has been studied, respectively, to explore the interaction between lights and matters in semiconductor material and the Mg-doped lithium niobate waveguide (MgO: PPLN) , with coupled wave equations and light transmission characteristics revealed. Based on back quasiphase-matching, characteristics of optical devices have been discussed in two new programs, that one is tunable bidirectional optical switch for c-band in the communication and visible red light, and the other is tunable optical bandpass filter with multiple flat-top bands for c-band in the communication. Otherwise, the concept of nanostructured resonator has been proposed, which is composed of the key components of optical devices, and the simulation and analysis and related performance parameters of transmission performance have been illustrated individually. The designed devices maybe open ideas, meaning and value for new applications of all-optical network.The main material of all-optical tunable optical switch is magnesium-doped lithium niobate waveguide (MgO: PPLN), for example, the central wavelength of signal is been set at 1550 nm, as the corresponding wavelength of idle at 730 nm, and the period of nanostructured resonator is up to hundreds of nanometer. For both signal and idle light, the output spectrum will form two flat-topped peaks, by controlling the variation of optical power to change these two peaks. Dramatically changing the transmission for the realization of passing windows provides the conditions for switching. To 3.64-cm magnesium-doped lithium niobate waveguide, for example, at 1549 nm or 1551 nm of the signal light, the extinction ratio reaches 8 dB as optical switching effect happens.The proposal of tunable optical bandpass filter with multiple flat-top bands has the same basic material magnesium-doped lithium niobate waveguide as nanostructured resonators composed. The output spectrum of signal light will form three flat-top bands, according to different optical power, and the changing bandwidth of peaks of the signal impacts on the choice of light. Moreover, the flat-top spectrum is related of the length of the waveguide structure and the quantity of nanostructured resonators. To 3.64-cm magnesium-doped lithium niobate waveguide, for example, the transmission width of band-pass filter can be changed in the range between 1.3 nm and 1.1 nm, while the band gap can be varied in the range between 0.1 nm and 0.4 nm.