Xiao-Fei Yang

Optical damage resistant Ti-diffused Zr/Er-codoped lithium niobate strip waveguide for high-power 980 nm pumping

Ti⁴⁺-diffused Zr⁴⁺/Er³⁺-codoped LiNbO₃ strip waveguide was fabricated on an X-cut LiNbO₃ substrate by thermal diffusion in sequence of Er³⁺, Zr⁴⁺ and Ti⁴⁺. Secondary ion mass spectrometry study shows that the Ti⁴⁺ ions follow a sum of two error functions in the width direction and a Gauss function in the depth direction of the waveguide. Both Er³⁺ and Zr⁴⁺ profiles follow the desired Gauss function, and entirely cover the Ti⁴⁺ profile. Optical study shows that the waveguide is TE or TM single mode at 1.5 μm wavelength, and has a loss of 0.3 (0.5) dB/cm for the TM (TE) mode. In the case of 980 nm pumping, the waveguide shows stable 1547 nm signal output under high-power pumping without optical damage observed, and a net gain of 1.1 dB/cm is obtained for the available pump power of 120 mW.

Near-stoichiometric Ti:Sc:LiNbO 3 strip waveguide for integrated optics

We demonstrate near-stoichiometric Ti:Sc:LiNbO3 strip waveguide fabrication starting from a congruent LiNbO3 substrate with a technological process in sequence of Sc3+-diffusion-doping, Ti diffusion, and post Li-rich vapor transport equilibration. We show that the waveguide is in a near-stoichiometric composition environment, well supports single-mode propagation at 1.5 μm wavelength under both TE and TM polarizations, shows considerable polarization dependence, and has a loss ≤ 0.4/0.7 dB/cm for TE/TM mode. The Ti4+ surface profile can be fitted by a sum of two error functions, the depth profile can be fitted by a Gaussian function, and the Sc3+-profile part which has a concentration above the threshold of photorefractive damage entirely covers the waveguide, showing that the waveguide is expected to be optical-damage-resistant.

Near-stoichiometric Ti-diffused LiNbO(3) strip waveguide doped with Zr(4+).

We report a near-stoichiometric Ti:Zr:LiNbO(3) strip waveguide fabricated from a congruent substrate with a technological process in the following sequence: Zr4+-diffusion-doping, diffusion of 8-μm-wide, 100-nm-thick Ti strips, and post-Li-rich vapor transport equilibration. We show that Zr(4+)-doping has little effect on the LiNbO(3) refractive index, and the waveguide is in a near-stoichiometric environment. The waveguide well supports both the TE and TM modes, shows weak polarization dependence, is in single mode at the 1.5 μm wavelength, and has a loss of ≤0.6/0.8 dB/cm for the TE/TM modes. A secondary ion mass spectrometry analysis shows that the Zr(4+)-profile part with a concentration above the threshold of photorefractive damage entirely covers the waveguide, implying that the waveguide would be optical-damage resistant.

Z-propagation Ti: Er: Tm: LiNbO3 strip waveguide with Er3+/Tm3+ codoped

We present z-propagation single-mode Ti: Er: Tm: LiNbO 3 strip waveguides on X-Cut congruent LiNbO 3 substrate. The waveguide has been fabricated by a technological process, starting with the preparation of the Er 3+ /Tm 3+ codoped LiNbO 3 plate, followed by the fabrication of 8-μm-wide Ti-diffused strip waveguide. The results of surface refractive indices by employing prism coupling technique shows Er 3+ /Tm 3+ codoped have no effects on the substrate index, and the surface composition was evaluated from the measured indices with the help of Sellmeier equation. We demonstrated the amplified simultaneous emission (ASE) spectra from the waveguide pumped at 980nm and 795nm without optical damage observed. The results shows that the co-doping combines the laser property of both ions, and the emission band around 1.5μm is about 150 nm, as a result, opening up a series of possibilities for stable, broadband amplifier devices by employing pump sources under 980nm and 795nm laser diodes.

Near-stoichiometric LiTaO 3 Optical Waveguides

Near-stoichiometric titanium indiffused LiTaO3 strip waveguides have been fabricated and characterized. The waveguides are polarization-insensitive, and the propagation losses are ~ 0.2 dB/cm and 0.3 dB/cm for TE and TM modes, respectively.

Polarization-insensitive, shallow Ti-diffused near-stoichiometric LiTaO 3 strip waveguide for integrated optics

We report on a Ti-diffused near-stoichiometric (NS) LiTaO3 strip waveguide fabricated by diffusion of an 8 μm wide, 160 nm thick Ti-strip followed by Li-rich vapor transport equilibration. It is found that the waveguide surface caves in ∼60  nm below the crystal surface. X-ray single-crystal diffraction shows that the indentation is due to Ti-induced lattice contraction. Optical studies show that the waveguide is in an NS composition environment, supports TE and TM single-mode propagation at 1.5 μm wavelength, is polarization insensitive, and has a shallow mode field profile and a loss of 0.2/0.3 dB/cm for the TE/TM mode. Secondary ion mass spectrometry analysis shows that the Ti profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of the waveguide. With the optimized fabrication condition, the waveguide is promising for developing an optical-damage-resistant device that requires a shallow mode field profile.