Waveguides In Nd Research Articles

Proton beam writing of Nd:GGG crystals as new waveguide laser sources

Focused proton beam writing has been utilized to fabricate optical channel waveguides in Nd:GGG crystals. The 1 MeV proton beam irradiation creates a local modified region with positive refractive index changes at the end of the proton trajectory, in which the channel waveguide could confine the light field in a symmetric way. Room-temperature laser emission has been achieved at 1063.7 nm, with absorbed pump power of 61 mW (at 808 nm). The obtained slope efficiency of the Nd:GGG waveguide laser system is as high as 66%, which is, to our best knowledge, the highest value for integrated lasers from ion beam processed channel waveguide systems.

High-contrast step-index waveguides in borate nonlinear laser crystals by 3D laser writing

We report the ultrafast fabrication of high-contrast step-index channel waveguides in Nd(3+):YCa(4)O(BO(3))(3) borate laser crystals by means of 3D direct laser writing. Guiding up to 3.4 μm wavelength is demonstrated for the first time in a laser written crystalline waveguide. Modeling the measured fundamental modes at the wavelengths of 1.9 µm and 3.4 µm allowed us to estimate the high laser-induced refractive index increments (index contrasts) to be 0.010 (0.59%), and 0.005 (0.29%), respectively. Confocal µ-Raman spectral imaging of the waveguides cross-sections confirmed that the cores have very well defined step profiles, and that the increase in the refractive index can be linked to the localized creation of permanent intrinsic defects. These results indicate that this crystalline waveguides are a potential candidate for the development of 3D active waveguide circuits, due to the laser and electro-optic properties of rare earth doped borate crystals.

Optical properties of a single mode planar waveguide in Nd:YVO_4 fabricated by multienergy He ion implantation

We fabricated a single-mode planar waveguide in z-cut Nd:YVO(4) by multienergy He ion implantation in total fluence of 4.5×10(16) ions/cm(2) at room temperature and investigated optical properties of Nd:YVO(4) before and after He ion implantation by measuring transmission, confocal microluminescence, and confocal Raman spectra. Absorption bands and the photoluminescence features of the bulk Nd:YVO(4) crystal have been preserved after He ion implantation. In Raman spectra, most of the peak positions and peak widths had no obvious change before and after He ion implantation. The guiding mode and near-field image in the waveguide were measured by the prism coupling method and end-face coupling method, respectively. We investigated the damage behavior of a Nd:YVO(4) waveguide after implantation, annealing treatment by the Rutherford backscattering/channeling technique. The minimum yield of the virgin z-cut Nd:YVO(4) was 1.98%, which increased to 4.73% after He ion implantation and decreased to 3.20% after annealing at 600 K for 30 minutes.

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.

Planar waveguides in Nd:SGG crystal formed by He ion implantation

In this paper, we report on the fabrication of planar waveguides in z-cut Nd:SGG crystals, using 500keV He ion implantation with fluences of 3×1016ions/cm2 at 77K1×1016ions/cm2 at room temperature, annealed at 260°C for 30min. The guiding modes of the planar waveguides were measured by the prism-coupling method at 633nm. The near-field intensity distribution and propagation loss of the light in the waveguides were measured by the end-fire coupling method. The absorption spectra were also measured. The refractive index profile was reconstructed using the intensity calculation method, and the light propagation mode was simulated with the finite-difference beam propagation method. The calculated results were in good agreement with the measured waveguide modes, indicating the feasibility of these designable devices.

Planar optical waveguides in Nd:BSO crystals fabricated by He and C ion implantation

Planar optical waveguides in Nd:BSO crystals were fabricated by the implantation of 500keV He ions and 6.0MeV C ions at two different substrate temperatures. The guiding modes were measured by the prism-coupling method with a He–Ne beam at 633nm. The intensity calculation method (ICM) and reflectivity calculation method (RCM) were used for reconstructing refractive index profiles. The near-field intensity distribution of the waveguide, formed by He and C ions implanted after annealing at 300°C, was measured by the end-face coupling setup. It was in reasonable agreement with the intensity of the waveguide mode simulated by the finite-difference beam propagation method (FD-BPM). The absorption spectra of the sample with He ions implanted at fluences of 3×1016ions/cm2 were measured using a spectrophotometer.

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.

Optical waveguides in Nd:GGG crystals produced by H^+ or C^3+ ion implantation

The optical waveguides in neodymium-doped gadolinium gallium garnet crystal are fabricated, to our knowledge for the first time, by either H(+) or C(3+) ion implantation. The reconstructed refractive index profiles of the planar waveguides have shown, in both cases, the typical "enhanced well" + "barrier" distributions. The two-dimensional modal profiles of the channel waveguides, obtained by using an end-face coupling arrangement, are in good agreement with the simulated modal distributions. After moderate thermal annealing at 200 degrees C, the propagation loss of the H- and C-ion-implanted channel waveguides are reduced down to approximately 1.5 and approximately 1.6 dB/cm, respectively, which exhibits acceptable guiding qualities for applications on potential integrated laser generation.

Proton-implanted optical channel waveguides in Nd : YAG laser ceramics

We report on the fabrication of optical channel waveguides in Nd : YAG ceramics by multi-energy proton implantation at a total dose of 8 × 1016 ions cm−2. The modal distribution of the guided modes obtained from numerical calculation was in good agreement with the experimental result. The propagation loss of the waveguide was determined to be ∼4 dB cm−1 after post-annealing up to 400 °C in air. Confocal micro-photoluminescence experiments have revealed relevant changes in the Nd spectroscopic properties in the waveguide's active volume. These changes include line broadening and shifting as well as a clear luminescence quenching, which were attributed to the strong structural modifications induced by the high-dose proton implantation.

Thermally resistant waveguides fabricated in Nd:YAG ceramics by crossing femtosecond damage filaments

We report on femtosecond laser writing of channel waveguides in Nd(3+) ion doped YAG ceramics by multiple inscriptions of damage filaments. Waveguiding between filaments was found to resist annealing temperatures as high as 1500 degrees C. Microluminescence imaging experiments have been carried out to elucidate the potential application of the obtained waveguides as integrated laser sources as well as to elucidate the waveguiding mechanisms.

Characterization of laser waveguides in Nd:CNGG crystals formed by low fluence carbon ion implantation

We report on Nd:CNGG active planar waveguides produced by 6.0 MeV carbon ion implantation at fluence from 1 × 10 14 ions/cm 2 to 8 × 10 14 ions/cm 2. The refractive index profiles, which were reconstructed according to the measured dark mode spectroscopy, showed that the refractive indices had negative changes in the surface region, forming typical barrier waveguide. The width of waveguide structure induced by carbon ion implantation is ∼3.8 μm. The typical barrier-shaped distribution may be mainly due to the nuclear energy deposition of the incident ions into the substrate. By performing a modal analysis on the observed TE modes, it was found that the TE 0 and TE 1 modes can be well-confined inside the waveguide.

Low-dose O3+ ion-implanted active optical planar waveguides in Nd : YAG crystals: guiding properties and micro-luminescence characterization

We report, for the first time to our knowledge, on the active optical planar waveguides in Nd : YAG laser crystals fabricated by O3+ ion implantation at low doses of ∼1014 ions cm−2. The reconstructed refractive index profiles based on the measured dark-mode spectroscopy show that an enhanced refractive index well is created in the near-surface region, forming a non-leaky waveguide structure. With thermal annealing treatment at 260 °C for 90 min, the propagation losses of the waveguides could be reduced to ∼3 dB cm−1 at a wavelength of 632.8 nm. The micro-luminescence investigation reveals that the emission bands of Nd3+ ions are not significantly affected by the waveguide formation processing, which shows promising potentials for efficient waveguide laser operations at near-infrared wavelength bands.

Low‐dose ion implanted active waveguides in Nd3+ doped near‐stoichiometric lithium niobate: promising candidates for near infrared integrated laser

AbstractBy applying low‐dose oxygen ion implantation, active planar waveguides in Nd3+ doped near‐stoichiometric lithium niobate laser crystals have been, for the first time to our knowledge, successfully produced. The waveguide exhibits good transmission properties with relatively low propagation loss of ∼2 dB/cm. The confocal micro‐luminescence investigations indicate that the emission properties of Nd3+ ions in the waveguide are well preserved with respect to the bulk, thus showing promising potentials for efficient waveguide laser action operating at the Nd3+ near‐infrared bands. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Scanning confocal fluorescence imaging and micro-Raman investigations of oxygen implanted channel waveguides in Nd:MgO:LiNbO3

The spatial variation of the spectroscopic properties of Nd3+ ions in oxygen implanted Nd:MgO:LiNbO3 channel waveguides have been investigated by scanning confocal microluminescence experiments. Although the radiative probabilities of Nd3+ ions were unaffected by the waveguide fabrication procedure, slight changes (in terms of spectral position and width of the emission lines) have been found in the electronic damage region. Raman spectra have been also analyzed in order to get a further understanding on the possible relation of these spectral changes with the micro-modifications induced during the waveguide formation.

Optical spectroscopy in channel waveguides made in Nd:YAG crystals by femtosecond laser writing

In this work, we present an optical characterization of channel waveguides fabricated by means of femtosecond laser writing on Nd:YAG substrates. These guiding structures show a refractive index increment of about 1×10 −3 which allows TE propagation. By pumping with a CW solid-state laser at 532 nm reaching the 2G 9/2 and 4G 7/2 manifolds of Nd 3+ ions, we have explored the emission band corresponding to 4F 3/2→ 4I 9/2 optical transitions (peaked at 890 nm). From data, we have found that emission showed similar characteristics for waveguide and bulk. On the other hand, the lifetime corresponding to the 4F 3/2 metaestable level was determined to be 240 μs for bulk and waveguide. Summarizing, we have made suitable channel waveguides in Nd:YAG crystals, by fs interaction, with similar spectroscopic properties to those of the bulk, a fact that boosters the photonics application of these devices. For the first time to our knowledge, a direct index increment waveguide made by interaction with ultra-short intense pulses in YAG crystals has been performed. This fabrication procedure can be an efficient tool to make several optical circuits in active materials by means of the one-step, fast and low-cost processing.

Characterization of optical waveguide in Nd: LuVO4 crystals by triple-energy oxygen ion implantation

Abstract We report on the optical planar waveguide formation and modal characterization in Nd:LuVO4 crystals by triple-energy O3+-ion implantation at energies of 2.4, 3.0, and 3.6 MeV and doses of 1.4, 1.4, and 3.1×1014 ions/cm2, respectively. The prism-coupling method is used to investigate the dark-mode property at a wavelength of 633 nm. The refractive index profiles of the waveguide are reconstructed by the reflectivity calculation method (RCM). The modal analysis shows that the fields of TE modes are well restricted in the guiding region, which indicates the formation of non-leaky waveguide in the crystal.

Oxygen ion-implanted optical channel waveguides in Nd : MgO : LiNbO3: fabrication, characterization and simulation

x-cut Nd : MgO : LiNbO3 wafers are implanted with 3 MeV O+ ions at a dose of 6 × 1014 cm−2, directly using a photoresist mask consisting of a series of open stripes of width 10 µm. The extraordinary refractive index (RI) experiences positive changes with respect to the bulk after ion bombardment and post-implantation annealing; therefore, channel waveguide structures are formed in the implanted regions. The near field intensity distributions of the transverse-electric modes are obtained by an end-fire coupling arrangement. The modal simulation result shows the reasonableness of the reconstructed RI profiles, which is helpful in designing practical waveguide devices produced by the ion implantation technique.

Characterization of optical waveguide in Nd: GdVO 4 by triple-energy oxygen ion implantation

We report on the optical planar waveguide formation and modal characterization in Nd: GdVO 4 crystals by triple oxygen ion implantation at energies of (2.4, 3.0, and 3.6 MeV) and fluences of (1.4, 1.4, and 3.1) × 10 14ions/cm 2. The prism-coupling method is used to investigate the dark-mode property at wavelength of 632.8 nm. The refractive index profiles of the waveguide are reconstructed by an effective refractive index, n eff method. The modal analysis shows that the fields of TE modes are well restricted in the guiding region, which means the formation of nonleaky waveguide in the crystal.

Carbon ion-implanted optical waveguides in Nd:YLiF 4 crystal: Refractive index profiles and thermal stability

We report on the optical planar waveguides in Nd:YLiF 4 laser crystals fabricated by 6.0 MeV C 3+ ion implantation at doses of 1 × 10 15 or 2.5 × 10 15 ions/cm 2, respectively. The refractive index profiles, which are reconstructed according to the measured dark mode spectroscopy, show that the ordinary index had a positive change in the surface region, forming non-leaky waveguide structures. The extraordinary index is with a typical barrier-shaped distribution, which may be mainly due to the nuclear energy deposition of the incident ions into the substrate. In order to investigate the thermal stability of the waveguides, the samples are annealed at temperature of 200–300 °C in air. The results show that waveguide produced by higher-dose carbon implantation remains relatively stable with post-irradiation annealing treatment at 200 °C in air.