Periodic inversion is reported for ferroelectric domains near the surface of z-cut lithium niobate crystals by a modified electric field poling technique. The depth of the inverted domain region extends to values of order a few μm (5-10 μm) below the surface of the crystal, thereby removing the high aspect ratio instability problems associated with bulk poling, and therefore allowing the fabrication of fine period ferroelectric domain structures. Using this method periods as short as 1 μm have been achieved. Such periodic domain distributions have been fabricated in Ti-indiffused and proton exchanged lithium niobate waveguides and our first quasi-phase-matching results are shown.
- Ferroelectric domain engineering
- Frequency conversion
- Lithium niobate waveguides