Nonlinear optical waveguides generated in lithium niobate by swift-ion irradiation at ultralow fluences

Low loss optical waveguides fabricated in LiTaO3 by swift heavy ion irradiation

Optical waveguides are fabricated by irradiation of LiTaO₃ with a variety of swift heavy ions that provide increasing levels of both nuclear and electronic damage rates, including C, F and Si ions, in the energy range of 15-40 MeV. A systematic study of the role of the ion fluence has been carried out in the broad range of 1e13-2e15 at/cm². The kinetics of damage is initially of nuclear origin for the lowest fluences and stopping powers and, then, is enhanced by the electronic excitation (for F and Si ions) in synergy with the nuclear damage. Applying suitable annealing treatments, optical propagation losses values as low as 0.1 dB have been achieved. The damage rates found in LiTaO₃ have been compared with those known for the reference LiNbO₃ and discussed in the context of the thermal spike model.

Refractive index engineering through swift heavy ion irradiation of LiNbO3 crystal towards improved light guidance

Swift heavy ion irradiation has been widely used to modify refractive indices of optical materials for waveguide fabrication. In this work, we propose refractive index engineering by swift heavy ion (Ar) irradiation via electronic energy deposition to construct waveguides of diverse geometries in LiNbO₃ crystal. The feasibility to modulate the refractive index of LiNbO₃ crystal at variable depths through electronic energy depositions of argon ions at different energies has been experimentally explored. The surface and cladding-like optical waveguides with thicknesses of ~13, ~36 and ~23 μm have been produced by using swift Ar ion irradiation at single energy of ~120, ~240, and double energy of (120 + 240) MeV, respectively. The fabricated waveguides are capable of effective waveguiding in single and multiple modes at 1064 nm, which enables efficient guided-wave second harmonic generation at room temperature. This work paves the way to produce waveguides with diverse geometries in dielectric crystals through electronic damage of multiple swift heavy ion irradiation.

Ridge waveguide lasers in Nd:GGG crystals produced by swift carbon ion irradiation and femtosecond laser ablation

We report on the fabrication of ridge waveguide in Nd:GGG crystal by using swift C(5+) ion irradiation and femtosecond laser ablation. At room temperature continuous wave laser oscillation at wavelength of ~1063 nm has been realized through the optical pump at 808 nm with a slope efficiency of 41.8% and the pump threshold is 71.6 mW.

Waveguide structures for the visible and near-infrared wavelength regions in near-stoichiometric lithium niobate formed by swift argon-ion irradiation

We report the fabrication of a waveguide structure in a near-stoichiometric lithium niobate crystal using 200-MeV argon-ion irradiation at a fluence of 2 × 10(12) ions/cm2. Guided modes were detected in the visible and near-infrared wavelength regions, suggesting that the waveguide can be used at fiber communications wavelengths. The refractive index profiles of the waveguide were reconstructed from the effective index functions. Micro-Raman spectra recorded in the waveguide layer and the substrate showed that the Li/Nb ratio was preserved in the waveguide layer after swift argon-ion irradiation.

Efficient laser emissions at 1.06 μm of swift heavy ion irradiated Nd:YCOB waveguides

We report on the fabrication of Nd:YCOB (Nd:YCa(4)O(BO(3))(3)) optical waveguides by using 170 MeVAr(8+) ion irradiation at an ultralow fluence of 2×10(12) ions/cm(2). The confocal microphotoluminescence investigation on the produced waveguides has shown the well-preserved fluorescence features within the guiding layer with respect to the bulks. Under the optical pump at wavelength of 810 nm, continuous wave waveguide lasers at 1061.2 nm have been generated at room temperature with a high slope efficiency of ~67.9%.

Continuous wave waveguide lasers of swift argon ion irradiated Nd:YVO4 waveguides

We report on the fabrication of planar waveguide in Nd:YVO(4) crystal by using swift Ar(8+) ion irradiation. At room temperature continuous wave (cw) laser oscillation at wavelength of ~1067 nm has been realized through the optical pump at 808 nm with a low threshold of 9.3 mW. The slope efficiency of the waveguide laser system is of 8.5%. The optical-to-optical conversion efficiency is 6.6%.

Second harmonic generation of swift carbon ion irradiated Nd:GdCOB waveguides

We report on the second harmonic generation at ~532 nm of optical waveguides in Nd:GdCOB produced by swift carbon ion irradiation. The fabricated waveguide shows good guiding property. Under pump of ~1064-nm fundamental light, the optical conversion efficiency of the frequency doubling is 0.48% W(-1) and 6.8% W(-1) for continuous wave and pulsed laser beams, respectively.

Swift nitrogen ion irradiated waveguide lasers in Nd:YAG crystal

We report on the fabrication, fluorescence and laser properties of optical waveguides by swift nitrogen ion irradiation in Nd:YAG crystals. The confocal micro-luminescence investigations have concluded that the fluorescence features of the bulk material have been well preserved in the waveguide. Under 808 nm optical end-pumping, continuous-wave (cw) laser oscillation at 1064.2 nm has been demonstrated with laser slope efficiencies of 16% and pump power thresholds of 38.3 mW.

Swift and heavy ion implanted chalcogenide laser glass waveguides and their different refractive index distributions

Planar waveguides have been fabricated in Nd- or Ho-doped gallium lanthanum sulfide laser glasses by 60 MeV Ar or 20 MeV N ion implantation. The refractive index profiles were reconstructed based on the results of prism coupling. The Ar implanted waveguides exhibit an approximate steplike distribution, while the N implanted ones show a "well + barrier" type. This difference can be attributed to the much lower dose of Ar ions. After annealing, the N implanted waveguides can support two modes at 1539 nm and have low propagation loss, which makes them candidates for novel waveguide lasers.

Swift heavy-ion irradiated active waveguides in Nd:YAG crystals: fabrication and laser generation

An Nd:YAG planar waveguide laser has been fabricated by ultra-low-fluence (2×10(12) cm(-2)) swift heavy-ion irradiation (60 MeV Ar(4+) ions). The appearance of the buried waveguiding has been associated with an increased refractive index layer as a consequence of the ion-induced electronic damage. Continuous-wave laser oscillations at 1064.2 nm have been observed from the waveguide under 808 nm optical excitation, with the absorbed pump power at threshold and laser slope efficiency close to 26 mW and 5.9%, respectively.

Optical channel waveguides in Nd:LGS laser crystals produced by proton implantation

Optical channel waveguides have been produced for the first time in Nd:LGS multi-functional laser crystals by using proton implantation. The obtained good guiding performance exhibits the well-confined modal fields in the waveguiding structures. The confocal fluorescence images of the obtained waveguides have revealed that the photoluminescence properties of the Nd(3+) ions have been well-preserved in the waveguide's active volume, which suggests promising applications as multi-functional integrated laser generation elements. These images have been also used to elucidate the spatial distribution of lattice damage and distortion caused by the implantation process, which are both mainly located at the nuclear collision region.

Fast dynamic waveguides and waveguide arrays in photorefractive Sn(2)P(2)S(6) induced by visible light

We report on dynamic waveguides and waveguide arrays induced beneath the surface of electro-optic Sn(2)P(2)S(6) crystals by visible light at 514 nm. The waveguide structures are generated by interband photoexcitation and drift or diffusion charge transport mechanism. These structures are probed nondestructively in the transverse direction with a beam at a longer wavelength. We measured the fastest formation of light induced waveguides in the visible up to now. The recording times are below 200 mus for intensities above 0.1 W/cm2. By interfering two light beams, dynamic waveguide arrays are generated with waveguide spacings of 7 microm. If an electric field is applied to the crystal, these arrays can be spatially shifted by 1.5 mum for an applied field of E(0) = 1 kV/cm.

Ion-implanted optical channel waveguides in neodymium-doped yttrium aluminum garnet transparent ceramics for integrated laser generation

We report, for the first time to our knowledge, on the fabrication of optical channel waveguides in neodymium-doped yttrium aluminum garnet transparent ceramics by oxygen implantation. The fabricated waveguides show reduced propagation losses (1.5 dB/cm), as well as the possibility of waveguide-mode tailoring. The confocal fluorescence images of the channel waveguides reveal that oxygen implantation causes only slight changes in the fluorescence properties of neodymium ions making the fabricated structures promising candidates for integrated laser sources in the infrared bands.

Ion implanted optical channel waveguides in Er3+/MgO co-doped near stoichiometric LiNbO3: a new candidate for active integrated photonic devices operating at 1.5 microm

We report on the fabrication of active optical channel waveguides in Er(3+)/MgO co-doped near stoichiometric lithium niobate crystals by means of selective low-dose oxygen ion implantation through a specially designed photoresist stripe mask. After post-implantation treatment at 260 degrees C for 1 h, the channel waveguides possess a propagation loss of approximately 1.7 dB/cm. The micro-luminescence investigation reveals that fluorescence emissions at approximately 1.5 microm in the waveguides are well preserved with respect to the bulk, exhibiting possible applications for integrated active photonic devices.