J.G. Scott

Nanoscale surface domain formation on the +z face of lithium niobate by pulsed ultraviolet laser illumination

Single-crystal congruent lithium niobate samples have been illuminated on the +z crystal face by pulsed ultraviolet laser wavelengths below (248 nm) and around (298-329 nm) the absorption edge. Following exposure, etching with hydrofluoric acid reveals highly regular precise domain-like features of widths ~150-300 nm, exhibiting distinct three-fold symmetry. Examination of illuminated unetched areas by scanning force microscopy shows a corresponding contrast in piezoelectric response. These observations indicate the formation of nanoscale ferroelectric surface domains, whose depth has been measured via focused ion beam milling to be ~2 micron. We envisage this direct optical poling technique as a viable route to precision domain-engineered structures for waveguide and other surface applications.

Continuous wave ultraviolet radiation induced frustration of etching in lithium niobate single crystals

Illumination of the -z face of congruent lithium niobate single crystals with continuous wave (c.w.) ultraviolet (UV) laser radiation modifies the response of the surface to subsequent acid etching. A frequency doubled Ar+ laser (lambda=244 nm) was used to illuminate the -z crystal face making it resistive to HF etching and thus transforming the illuminated tracks into ridge structures. This process enables the fabrication of relief patterns in a photolithographic manner. Spatially resolved Raman spectroscopy indicates preservation of the good crystal quality after irradiation.

UV radiation-induced surface wetting changes in lithium niobate single crystals

Irradiation of lithium niobate crystal surfaces with UV radiation modifies the wetting properties of the surface which becomes super-hydrophilic. This effect is used for spatially selective attachment of chemical species on the laser exposed areas.

Nano-scale ultraviolet laser-induced ferroelectric surface domains in lithium niobate

In this contribution we are reporting all-optical poling, or direct domain inversion induced by light without an applied electric field, in lithium niobate. Potential advantages of such a technique are the reduction of fabrication steps, removing the need for photolithography, and allowing the domain microstructuring to be directly defined by the illumination pattern alone. This may lead to smaller domain sizes as compared with electric field poling which is currently limited to domain sizes of several micrometers.

Sub-micron filamentary structures formed during light induced frustrated etching of fe-doped lithium niobate: results and modelling

Lithium niobate is a versatile optical material with many applications that result from its wide range of electro-optic, nonlinear, photorefractive and piezoelectric properties. The ability to produce complex, yet controllable, aligned structures in lithium niobate without the need for photolithographic patterning, would allow the implementation of a range of applications such as Bragg and relief grating, periodically poled structures, and miniature electro-optic devices.