Studies On Two-dimensional Optical Phased Array On Silicon-on-insulator

Optical phased arrays is an array system which can provide agile and precise freespace optical beam steering free of any mechanical structure,each array element can achieve the phase control of radiation field,then the far-field intensity distribution is controlled to achieve beam scanning.With the development of processing technology in the field of photonic integration,the optical phased array on chip has gradually come under the spotlight of tremendous researchers,and it also has been widely used in areas such as free-space board-to-board optical interconnects and light detection and ranging.In this thesis,the related silicon based photonic devices are designed to compose the array system.By eliminating the grating lobe,the on-chip two-dimensional optical phased array can achieve a wide two-dimensional steering range.Firstly,we investigate the development of optical phased array both in domestic and abroad,and find that the on-chip optical phased array developed from one-dimensional form to two-dimensional form.Two schemes for on-chip optical phased array are summarized to achieve two-dimensional beam steering: single wavelength design and multiple wavelength design,and the limitation of these plans is pointed out.And then,the far-field imaging principle of optical phased array is analyzed through the physical model of multi-slit Fraunhofer diffraction.We explained the physical process of eliminating grating lobe,which helps to provide a method to solve the grating lobe problem.With the help of analyzing the two-dimensional antenna array model,we deduced the law of phase control for every array element for a specific beam steering angle.We researched a kind of numerical calculation method: Finite-Difference TimeDomain method,to guide the design and simulation of our devices.In the third part of this thesis,we present the scheme of the optical phased array system as single wavelength input and two-dimensional nanoantenna array,and the nanoantenna,the phase controller and the directional coupler are designed according to the system scheme.The length and width of the antenna are less than 3?m.For a source of 1310 nm an efficient 51% up-emission is achieved and the far-field divergence angle of the antenna reaches 50 degrees.A 99% transmission C-bend waveguide is designed as optical phase shifter for array element.A uniform near-field emission profile was achieved in the optical phased array utilizing the proposed optical power delivery network which is based on the directional couplers.Finally,according to the guidance of the elimination grating lobe algorithm,the step function of different forms is selected to optimize the spacing of the array element.The step function is determined to be sinusoidal considering the effect of the compression grating lobe and the requirements of the process.After the suitable step coefficient is selected,the side-lobe-level is-6dB to-7dB when the main lobe is not steer,and when the main lobe steers to the 3dB critical point,the steering range reaches 34×14 degrees.