Method and structure of electric field poling of Ti indiffused LiNbO
View Patent ↗A method and structure are disclosed with a simplified approach for fabricating a LiNbO3 wafer with Ti indiffusion wafeguide on the surface that is domain inverted. The method involves indiffusing Ti into LiNbO 3 with a predefined temperature and time indiffusion range, a Li enriched and dry oxygen atmosphere, which allows making optical waveguides on the z− crystal face without any significant domain inversion occurring on the z+ face of the crystal. This allows for subsequent poling without the need of any additional removal of the thin domain inverted layer which would otherwise appear on the z+ face. Even in instance where a thin domain inversion layer is formed, it is insufficient thick to prevent poling, eliminating the need for the grinding process.
1. A waveguide fabrication method, comprising:
providing a predefined temperature with a time indiffusion range;
indiffusing Ti into an LiNbO 3 substrate in a furnace at a low temperature in a specified atmosphere; and
forming an optical waveguide on the z− crystal face of the substrate without any domain inversion occurring on the z+ crystal face; and
poling the Ti indiffused LiNbO 3 substrate without having to remove a thin domain inverted layer which would otherwise appear on the z+ crystal face.
wherein the diffusing step comprises indiffusing Ti into the LiNbO 3 substrate in a furnace with a lithium enriched and dry oxygen atmosphere.
2. The method of claim 1 , after the forming step, further comprising applying high voltage pulses via liquid or solid electrodes.
3. The method of claim 1 , further including forming a predefined pattern of insulating material on the z− crystal face.
4. The method of claim 3 , wherein the insulating material is SiO 2 .
5. The method of claim 1 , wherein the predefined temperature is 1030° C.
6. A method for waveguide fabrication process, comprising:
providing a predefined temperature with a time indiffusion range;
indiffusing Ti into an LiNbO 3 substrate in a furnace with a Li/O 2 enriched atmosphere; and
forming an optical waveguide on the z− crystal face without any domain invasion occurring on the z+ crystal face.
7. The method of claim 6 , wherein the step of indiffusing Ti into the LiNbO 3 substrate is performed at a low temperature.
8. The method of claim 7 , after the forming step, further comprising applying high voltage pulses via liquid electrodes.
9. The method of claim 8 , further comprising poling the Ti indiffused LiNbO 3 substrate without the need of removing a thin domain inverted layer which would otherwise appear on the z+ crystal face.
10. The method of claim 6 , wherein the Li/O 2 enriched atmosphere in the furnace substantially prevents Li 2 O out-diffusion.
11. A method for use in forming a waveguide, comprising:
placing at least one LiNbO 3 wafer on tray while flowing oxygen through a tube;
positioning the tray and the at least one LiNbO 3 wafer into the tube and increasing a temperature in the tube to a predetermined temperature while flowing oxygen through the tube;
indiffusing Ti into the LiNbO 3 wafer and forming the waveguide while flowing oxygen through the tube;
reducing the temperature in the tube to a predetermined temperature while flowing oxygen through the tube; and
stopping the flow of oxygen through the tube and removing the tray from the tube.
12. The method of claim 11 , further comprising removing the LiNbO 3 wafer from the tray and poling the Ti indiffused LiNbO 3 wafer without having to remove a thin domain inverted layer which would otherwise appear on the z+ crystal face.