Graded index single crystal (GRISC) active waveguide in glass



The invention introduces a method for fabricating ferroelectric crystal
lines for use as low loss optical waveguides with additional active

functionality compared to amorphous/glass waveguides.

It provides low losses by confining the light signal tightly in the

crystal core, away from the rough crystal-glass

interface that is often responsible for losses in such a system. These

new types of  waveguides consisting of active crystals, such as lithium

niobate, in glass, can be fabricated in complex architecture, suitable

for realizing integrated optical elements within the glass substrate at

low cost. GRISC waveguides have much lower losses than other

competing options.


The GRISC in glass is created through

control of the temperature distribution induced by femtosecond laser

heating. Within the glass, the femtosecond laser induced temperature

profile allows for crystallization upon heating, ahead of the laser focus.

The refractive index contrast generated using this method leads to tight

optical confinement of the transmitted light in a Gaussian profile. Such

a profile results in most of intensity in the center where losses are low,

and very low intensity near the crystal-glass interface where losses tend

to be high.


Competitive Advantage


Glass cannot fundamentally possess some of the active capabilities of

optical crystals like lithium niobate, which are required in optical communication,

such as high electro-optic coefficient and second order optical nonlinearity.

This invention allows for such

optical crystals to be integrated as low loss optical waveguides with

active properties that additional functionalities than those of amorphous/glass

waveguides. Other advantages conferred by this invention include the

ability to fabricate GRISC in glass and ensure radially symmetric crystal

misorientation of the crystal line. The growth mode proposed eliminates

the problem of non-uniform polycrystallinity. Misorientation also helps

decrease the refractive index of the crystal line and helps in producing

optically active GRISC waveguide within glass.


Market Need/Opportunity


This invention would be useful in different market segments

associated with photonics and optical equipment. The demand for silicon

photonics technology has increased owing to their various functionalities

and day-to-day use in data communication and telecommunication

applications for high bandwidth data transmission in small and large

networks. GRISC can be used as a low loss optical waveguide to

improve integrated optic devices such as electro-optic modulators. With

rare earth doping, GRISC can be used in optical quantum memory





Lehigh University is looking for a partner for further development and

commercialization of this technology through a license. The inventor is

available to collaborate with interested companies.


Tech - ID




Keith Veenhuizen

Volkmar Dierolf

Himanshu Jain, PhD

For Information, Contact:
Rick Smith
Lehigh University
Keith Veenhuizen
Volkmar Dierolf
Himanshu Jain