Characteristics of acoustooptic devices for generating symmetric diffracted scanning beams

This paper presents analysis and comparison of acoustooptic device types for generating symmetric diffracted scanning beams. This is a special mode of operation with applications such as dynamic beam tracking and control and variable beam splitting. This mode differs from most acoustooptic device operation, typically based on Bragg single sideband mode. Configurations of interest include: Raman Nath (short interaction length - low Q or L/L₀); phased array, and birefringent phase matched - all in axial symmetric modes - where the input optical beam is normal to the main acoustic beam axis. Primary considerations are the acoustooptic bandshapes and diffraction efficiency per input power. It is found that the axial birefringent diffraction modes and acoustic array beam steering modes provide higher diffraction efficiency for allowable bandshape ripple for comparable material constants. This is especially pronounced for small scanning fractional bandwidth compared to an octave.