Surface-emitting electroholographic SAW modulator

Abstract

We report the design and operation of a surface-emitting surface acoustic wave (SAW) acousto-optical modulator which behaves as a cm-scale linear hologram in response to an applied electronic waveform. The modulator is formed by an optical waveguide, transducer, and out-coupling surface grating on a 1 mm-thick lithium niobate substrate. We demonstrate the ability to load and illuminate a 9-region linear hologram into the modulator's 8 mm-long interaction region using applied waveforms of 280–320 MHz. To the best of the authors’ knowledge, this is the first demonstration of a monolithically-integrated, surface-emitting SAW modulator fabricated using lithographic techniques. Applications include practical implementations of a holographic display.

30‐4: Electroholographic Display Based on a Horizontal Array of Edge‐Emitting Surface Acoustic Wave Modulators

“…Modulator operation is summarized in Section 2 of [8]. The following brief recap refers to our Figure 3.…”

“…As an additional direction, note that each emitter requires its own waveform; that is, a hypothetical 1024 × 768 display would require nearly 800,000 signals, absent multiplexing. A solution to this challenge is provided by surface-emitting SAW modulators, in which each input waveform generates a SAW whose cm-scale propagation defines multiple pixels or hogels [8] rather than one.…”

Status of Leaky Mode Holography

“…There have been a number of variations of the device described above, but all such instantiations have had the following fundamental ingredients: an input coupler, an anisotropic waveguide, and an interdigital transducer (IDT). Input coupling has been accomplished by prism coupling (into general devices) [11], prism coupling into leaky mode devices [1,12], and grating or grating-and-fiber coupling into leaky mode devices [13,14]. Anisotropic waveguides for electroholographic display have been indiffused in both z-cut x-propagating and x-cut y-propagating lithium niobate substrates using any one of several proton exchange techniques [15].…”

“…IDTs have typically been patterned from aluminum layers with a possible titanium adhesion layer [17]. The output light has exited either from the edge of the device [1,14], or from the bottom [18], or top (IDT-bearing) surface [12].…”

“…Surface-emitting devices, which have been demonstrated in top-emitting (IDT face) and bottom-emitting varieties, have many attractive features as described by McLaughlin [18] (see Figure 10a) and Jolly [48], with the first monolithic demonstration (using prism coupling) in [12,49]. A surface exit allows for decoupling of interaction length from the substrate thickness and the abutting of tiles to create large displays.…”