| A novel type of waveguide optical phased array(WOPA)is studied.It has many advantages and can provide an elegant means for the intertialess,high-resolution random-access beam scanning.In particular,this optical phased array(OPA),which has characteristics of large scanning area,rapid scanning speed,low drive voltage,small bulk and skillful processing technology,is likely to conquer the bottleneck of laser scanning imaging.It provides a new developing direction and has great application prospect both in military and civilian domain such as laser scanning imaging,laser radar, laser display,optical switch,laser printing and so on.Theory on waveguide optical phased array is discussed in detail.Intensity distribution of radiation beam is studied for both 1-D and 2-D OPA by grating diffraction theory. The principle and method of suppression of sidelobes are discussed by abnormity setting of different phased parts.Electro-optic effect of optical waveguide array(OWA) is discussed and electro-optic scanning theory is investigated.Both the general electrocontrol scheme and the 2πelectro-control scheme of WOPA are discussed and the results show that the 2πelectro-control scheme is much better than the general scheme. Propagating characteristics of both a single optical waveguide and OWA are discussed and coupling characteristics of OWA are studied in detail.The coupling equation group, which describes coupling characteristics of OWA,is solved by Laplace transform for the first time and then coupling characteristics of OWA are studied under two conditions that considering coupling between adjacent waveguides and considering coupling among both adjacent waveguides and hypo-adjacent waveguides.Coupled-mode theories on both non-parallel waveguides and curve waveguides are studied and then coupling characteristics are discussed by numerical calculation.Coupled-mode equations for waveguides with different core refractive index are solved and coupling characteristics are studied afterwards.Effects of waveguide coupling on propagating characteristics,radiating characteristics and scanning characteristics of WOPA are studied by use of the finite-difference beam-propagation method(FD-BPM)comprehensively for the first time.The results show that waveguide coupling has great effect on characteristics of WOPA and should be emphasized in application.FD-BPM,with considering effects of both waveguide intensity coupling and phase on propagating characteristics,is much better for describing characteristcis of WOPA than the grating diffraction theory,so the results obtained are meaningful for both designing structure of OWA reasonably and improving scanning characteristics effectively.According to the demand of beam scanning application,design principle of the structure of OWA is studied,optimizating design of waveguide cladding thickness is discussed,suppression of sidelobes is studied by the method of designing structure of OWA and then a patent of invention is applied.According to the electro-control theory and the 2πelectro-control scheme,two kinds of driving source,based on singlechip and Field Programmable Gate Array(FPGA),are developed.Both the two driving sources can export 10 routeways voltage with range of±10V and can realize both manual and auto scanning.Voltage variety frequency for the driving source based on singlechip is 800Hz and for that based on FPGA is 10MHz.OWA with 10 waveguides is developed,and experimental system for WOPA is set up. Experiments on both OWA and WOPA are studied and beam scannning at 1-D is realized.The max beam deflecting angle is 13.6°,scanning frequency is 800Hz and the max driving voltage needed is 8.7V.The results confirm principle and feasibility of WOPA.Furthermore,diffraction phenomenons in experiment are discussed in theory and based on the results obtained,farther research direction is put forward.
|
PDF Full Text Request