Opto-optical light deflection

Light deflection is accomplished by diffraction from a transient index modulation established as a grating of variable frequency in an optical material by the interference of two controlling light beams. This device may be considered an opto-optical analog to an acoustooptical deflector, in that a change in angular deflection is created by altering the frequency of the diffraction grating. In this paper we report on a technique for altering the grating frequency by changing the wavelength of the control beams and the use of a novel optical system to maintain the Bragg condition over a wide range of frequencies. Configurations exhibiting very large angular deflections have been designed using a computer simulation and optimization program that allows minimization of the Bragg detuning. This new method of light deflection allows either discrete or continuous light scanning or modulation. A particular example using lithium niobate will be discussed which produces an 11.8 degrees deflection from a 0.027-micron wavelength change and with an angular detuning of lessthan +/-0.03 degrees. The use of other materials, inorganic, organic, and dispersive, will also be discussed.