Optical Devices Design And Propagation Properties Of Nano-photonics Structures

Photonics,which treat photon as the main information carrier,is an important subject.In the 21st century,with the rapid development of science and technology,optical information technology plays an important role in all fields.Photonics technology,which based on the classical optical theory,due to the diffraction limit,is difficult to have breakthrough of development at the nanoscale.Therefore,an important new concept-nanophotonics,which beyond the classical optical diffraction limit,is presented.This thesis mainly studies the optical propagation properties of single and periodic nanophotonic structures,and presents some optical devices.And we discuss the application in sensor and integrated optics.It mainly include the following works:(1)We present a surface plasmon resonance biosensor based on grating structures.Compared with the conventional gold(Au)-based or silver(Ag)-based SPR sensor,the simulation results based on FDTD method show that the aluminum(Al)-based sensor has the best performance,and the sensitivity of the sensor is 247.2°/RIU(degree per refractive index unit).(2)We present a polarizing beam splitter based on a double-layer subwavelength grating.The simulation results based on RCWA method show that both the zero-order reflection for TE polarization and the zero-order transmission for TM polarization can exceed 90%in a wide tunable working incident angle range from 48° to 72° and a wide working wavelength range from 1500 to 1600 nm.(3)We study the high refection feature of high-contrast grating,and present a beam focusing reflector.The simulation results based on FDTD method show that the device has the capability of focusing both TE and TM polarized lights for wavelength range from 1.55?m to 2?m.(4)We present a fully analytic theory for nanorod resonances including the phase of reflection from the rounded ends using a transmission line approach.It combines the circuit theory response of spherical nanoparticles with standard transmission line theory.The approach agrees well with comprehensive numerical calculations.(5)A new phenomenon that an obvious deep of the transmission from subwavelength slits can be obtained if we change the wavelength of the incident light in the visible regime is proposed.Theory,FDTD simulation and experiments all show that there exist maximum reflectivities if we change wavelengths for different slit widths from 20 to 70 nm.(6)We study the third-harmonic generation response from double nanohole aperture in gold film with different gaps.We experimentally demonstrate that double nanohole with smaller gap can obtain a stronger third-harmonic generation signal.In addition,finite-difference time-domain simulations show the same behavior.