P. Moretti

Designable buried waveguides in sapphire by proton implantation

Buried and stacked planar as well as buried single and parallel channel waveguides are fabricated in sapphire by proton implantation. Good control of the implantation parameters provides excellent confinement of the guided light in each structure. Low propagation losses are obtained in fundamental-mode, buried channel waveguides without postimplantation annealing. Choice of the implantation parameters allows one to design mode shapes with different ellipticity and/or mode asymmetry in each orthogonal direction, thus demonstrating the versatility of the fabrication method. Horizontal and vertical parallelization is demonstrated for the design of one- or two-dimensional waveguide arrays in hard crystalline materials.

Room-temperature continuous-wave operation of Ti:sapphire buried channel-waveguide lasers fabricated via proton implantation

Fabrication and laser operation of proton-implanted Ti:sapphire buried channel waveguides is reported for the first time to our knowledge. Without any postimplantation annealing of the structures, continuous laser operation near 780 nm was demonstrated at room temperature at an absorbed pump power threshold of 230 mW. Single-transverse-mode laser emission was observed with measured beam propagation factors M(2)(x) and M(2)(y) of 1.5 and 1.2, respectively. An output power of 12.4 mW for 1 W pump power was obtained with an output coupler of 4.6% transmission at the signal wavelength. Higher output powers were measured in waveguides with larger cross sections exhibiting multimode laser emission.

Formation of planar optical waveguides in potassium titanyl phosphate by double implantation of protons

The formation of planar waveguides in potassium titanyl phosphate by H+ ions implantation at low energy is presented and discussed. The energy and dose were (600+550) keV and (1+0.8)×1016 ions cm−2, respectively. The optogeometrical parameters deduced from the optical characterization are the following: −3% for each refractive index variation (nx, ny, and nz) and a guide thickness of 4.3 μm. A good agreement is found between the value given by the top of the nuclear damages profile obtained by transport of ions in matter code and the value given by the index fall position. Losses measured in nonannealed samples were estimated to be less than 5 dB cm−1.

All-optical beam deflection and switching in strontium-barium-niobate waveguides

Self-focusing by thermal heating because of absorption of a guided light beam in a planar strontium–barium–niobate waveguide is of interest for all-optical data processing. When a guided probe beam intersects the pump beam under a small angle inside the waveguide, the self-focusing effect in conjunction with self-bending because of the photorefractive effect can be used for large angle deflection of the probe beam and for switching with time constants of fractions of milliseconds. Deflection angles of the outcoupled probe light up to 0.23 rad in air and frequencies up to 3 kHz for optical switching are reached in the experiment.

Optical near-field measurements of guided modes in various processed LiNbO3 and LiTaO3 channel waveguides

Abstract Scanning near-field optical microscopy (SNOM) technique has been used in collection mode to probe the evanescent field at the surface of channel waveguides fabricated in LiNbO 3 and LiTaO 3 either by ion exchange, titanium in-diffusion or ion implantation. A specific sample holder has been developed on a commercial system. The intensity distribution of guided modes in the different waveguides, and the associated topographical images, have been obtained and compared among them, giving relevant information about the structure of the various waveguides. The effective index of guided modes has been deduced from the measurement of the intensity variation of the evanescent field as a function of the distance from the waveguide surface.

Optimization of photorefractive LiNbO3 waveguides fabricated by combined techniques of ion exchange and implantation

Abstract Photorefractive waveguides (PRWs) are fabricated by helium implantation in LiNbO 3 doped via proton-assisted copper exchange. Fabrication conditions have been optimized to reach high diffraction efficiency of photorefractive holographic gratings. Fanning of the guided light is found to be a key factor limiting holographic recording performance in our newly developed waveguides.

Fabrication of optical planar waveguides in KY(WO/sub 4/)/sub 2/ by He-ion implantation

In this paper, planar waveguides produced by He-ion implantation have been demonstrated in undoped and Yb-doped KY(WO/sub 4/)/sub 2/ crystals. The effective refractive indices of guided modes in surface planar waveguides were measured by dark m-line spectroscopy and the refractive index profiles were reconstructed by calculations based on the inverse WKB method. The end-faces of implanted crystals were polished and the waveguiding properties of the obtained planar structures were investigated using a laser diode at 980 nm and a CCD camera.

The SHEW technique as a simple method to characterize the non-linear properties of crystals: investigation of helium implantation effects in LiNbO3 and KTiOPO4

Abstract The Second Harmonic wave generated with Evanescent Wave (SHEW) technique is first applied to measure the value of the non-linear coefficient, d 33 , of lithium niobate (LN). The result is in good agreement with the known value from the literature. We subsequently investigate the second-order optical properties of the near surface of He + -implanted LN and KTiOPO 4 (KTP) crystals. Our results show a rather strong degradation of the non-linearity (≈50%) in both crystals.

H/sup +/ implanted channel waveguides in buried epitaxial crystalline YAG:Nd,Tm layers and infrared to blue upconversion characterization

In this paper, we have developed a new route to fabricate channel waveguides, by using ion implantation technique in buried epitaxial crystalline YAG:Nd,Tm layers. Excited state absorption and energy transfer upconversion mechanisms are discussed in view of a single beam pumped infrared to blue upconversion laser for integrated optics.