Digital Planar Holography (DPH) provides control and processing of light, propagating inside a planar light waveguide. The DPH was developed in attempt to make possible fabrication of numerous micro-optic devices for integrated optics. Computer-generated holograms are the best candidates for the purpose, provided the limitations of traditional holography, associated with a short light path in thin holograms and with difficult if not impossible access to internal areas of thick holograms, are eliminated. The DPH does just that by embedding holographic structures into planar waveguides. This is an ideal configuration for Photonic Lightwave Circuits (PLC).

Holographic structures on one or several planar waveguide interfaces can be generated in a computer and created with well-developed methods for fabrication of electronic integrated circuits, such as micro-lithography. Nano-imprinting also can be used. The both methods provide inexpensive mass-production of DPH devices. The planar waveguide interfaces are easily accessible for embedding the DPH structures, consisting of multiple nano-features, positioned in the configuration, optimal for a device with given parameters. The nano-features, for example, etched nano-grooves, modulate spatially the waveguide refractive index, steering light in required directions. Therefore, the DPH technology combines the power of thick (volume) holograms with easy access to the structure pattern for thin holograms and with automated manufacturing of digital holograms.

A typical DPH device comprises several million nano-features, which could be placed in a huge number of combinations, but only a few of them will be working efficiently. Finding optimal configuration of the nano-features is the main task during device design. This can be accomplished only with specialized software, running on a powerful computer. NOD proprietary programs provide design and simulation of DPH structures and are a crucial part of the DPH technology. Optical transfer functions are encoded in the positions of millions of identical grooves (lines), ~ 100 nm wide each. Both design and simulation of DPH devices rely strongly on theoretical physics and computer science.

A high magnification image of a DPH structure (a small fragment of a high resolution dispersive nano-grating), obtained with a scanning electron microscope, is presented below.

Our devices are fabricated on standard wafers and diced in small chips. Typically the waveguide core is 200 - 600 nm thick, while nano-grooves, embedded into it are ~100 nm wide and 10 - 100 nm deep. The size of a typical DPH nano-grating is shown in the next photo in comparison with a coin.

The DPH devices beat competitors in size and performance. They can be easily customized for multiple applications. For example, we can design and fabricate nail-sized nano-gratings for absorption, emission, and Raman spectroscopy. The DPH technology is beneficial also for optical interfacing multiple active and passive photonic devices on the same chip, for combining or separating multiple laser beams, for increasing laser efficiency, and many other applications.

The nearest future Applications for the DPH technology are Nano-Spectrometers, Nano-Sensors, and Integrating Elements for Planar Lightwave Circuits.