Waveguides In Nd Research Articles

Optical ridge waveguides in Nd:CNGG disorder laser crystal produced by combination of carbon ion irradiation and precise diamond blade dicing

Ridge waveguides have been produced in Nd:CNGG disorder laser crystal by using precise diamond blade dicing of carbon ion irradiated planar waveguide. The propagation loss of the ridge waveguide is measured to be ∼3.8dB/cm at the wavelength of 632.8nm. The micro-Raman spectrum indicates that the microstructure of the Nd:CNGG crystal has no significant change after the carbon ion irradiation. The microphotoluminescence feature has been found well preserved in the waveguide structure. The thermal stability of the waveguide has been investigated, showing relatively stable feature below 260°C.

Ridge waveguides in Nd:ABC3O7 disordered crystals produced by swift C5+ ion irradiation and precise diamond dicing: Broad band guidance and spectroscopic properties

Abstract Optical ridge waveguides have been manufactured in the crystals of Nd:SrLaGa 3 O 7 and Nd:SrGdGa 3 O 7 by combining techniques of swift carbon ion irradiation with precise diamond blade dicing. The guiding properties of the waveguides are investigated at broadband (at wavelength of 633 nm, 1064 nm, and 4 µm). After annealing treatment at 200 °C for 1 h, the propagation losses of ridge waveguides could be reduced to as low as 1 dB/cm. The confocal microfluorescence emission spectra confirm that the fluorescence properties of Nd 3+ ions are almost unchanged after the ion irradiation processing, showing promising potentials as application of miniature light sources in integrated optics.

Femtosecond laser-written double-cladding waveguides in Nd:GdVO4crystal: Raman analysis, guidance, and lasing

We report on waveguide lasers at 1064.5 nm in femtosecond laser-written double-cladding waveguides in Nd:GdVO4 crystals. The cladding waveguides guide both transverse electric (TE)- and transverse magnetic (TM)-polarized modes with considerably symmetric single-modal profiles and show good transmission properties (propagation loss as low as 1.0 dB/cm). The detailed structure of the single and double claddings has been imaged by means of μ-Raman analysis, and the observed slight fabrication asymmetries with respect to an ideal circular cladding are in well agreement with the observed differences in TE/TM propagation losses. Importantly, the Raman imaging shows the complete absence of lattice defect at the laser active volume. Under the optical pumping at 808 nm, a maximum output power up to 0.43 W of the continuous wave waveguide laser with a slope efficiency of 52.3% has been achieved in the double-cladding waveguide, which is 21.6% and 23% higher than that from a single-inner cladding waveguide. Furthermore, the maximum output power of the waveguide laser is 72% higher than that of the double-line waveguide due to the double-cladding design.

Efficient laser emission from cladding waveguide inscribed in Nd:GdVO(4) crystal by direct femtosecond laser writing.

We report on the fabrication of depressed cladding waveguides in Nd:GdVO(4) laser crystal by using femtosecond laser inscription. The cross section of the structure is a circular shape with a diameter of 150 μm. Under the optical pump at 808 nm, the continuous wave (cw) as well as pulsed (Q-switched by graphene saturable absorber) waveguide lasing at 1064 nm has been realized, supporting guidance of both TE and TM polarizations. The maximum output power of 0.57 W was obtained in the cw regime, while the maximum pulse energy of the pulsed laser emissions was up to 19 nJ (corresponding to a maximum average output power of 0.33 W, at a resonant frequency of 18 MHz). The slope efficiencies achieved for the cw and pulsed Nd:GdVO(4) waveguide lasers were as high as 68% and 52%, respectively.

Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique

We report on realization of buried waveguides in Nd:YAG ceramic media by direct femtosecond-laser writing technique and investigate the waveguides laser emission characteristics under the pump with fiber-coupled diode lasers. Laser pulses at 1.06 μm with energy of 2.8 mJ for the pump with pulses of 13.1-mJ energy and continuous-wave output power of 0.49 W with overall optical efficiency of 0.13 were obtained from a 100-μm diameter circular cladding waveguide realized in a 0.7-at.% Nd:YAG ceramic. A circular waveguide of 50-μm diameter yielded laser pulses at 1.3 μm with 1.2-mJ energy.

Planar Nd:YGG waveguide fabrication by multiple energy He ion implantation

Rare-earth garnet single-crystals are promising candidates for optical applications. Previous reports showed that they have controllability and good reservation of Nd ions fluorescent properties in the ion implanted waveguide. Thus, we studied the optical and fluorescent properties of the Nd:YGG waveguide structure formed by multi-energy He ion implantation. The fabrication and characterization of the optical planar waveguide in Nd:YGG crystal by using multi-energy He ion implantation was presented. The thermal stability of our ion-implanted Nd:YGG crystal was investigated. The guided-mode and annealing properties at the wavelength of 633nm were investigated through prism-coupling and end-face coupling measurements, and the fluorescent properties were investigated by a confocal micro-luminescence experiment. This work could supply an operation reference for integrated optical devices.

Channel waveguide lasers at 1064 nm in Nd:YAG crystal produced by C5+ ion irradiation with shadow masking

We report on the fabrication of channel waveguides in Nd:YAG crystals, using swift C⁵⁺ ion irradiation with ion energy of 15 MeV and fluence at 5×10¹⁵ ions/cm². A laser-cut shadow mask of a number of open stripes with varied width was covered on the sample surface during the ion irradiation. Channel waveguides were formed in the Nd:YAG crystal due to the refractive index increase along the ion trajectory. Room temperature waveguide laser oscillations at 1064 nm have been observed under 808 nm optical pumping, with laser slope efficiency at 38% and a maximum output power of 36 mW.

Enhanced Second Harmonic Generation in Femtosecond Laser Inscribed Double-Cladding Waveguide of Nd:GdCOB Crystal

We report on the fabrication of double-cladding waveguides in Nd:GdCOB crystals by using femtosecond laser inscription with scanning speed of 0.5 mm/s. This prototype consists of two concentric tubular structures with nearly circular cross sections with different diameters. The fabricated cladding waveguides possess relatively low propagation losses of less than 0.65 dB/cm. The micro photoluminescence and second harmonic confocal images of the fabricated waveguides, which were performed by using a confocal microscope, have revealed that neither the fluorescence nor the nonlinear properties of the constituent crystals have been deteriorated during femtosecond laser micromachining procedure. Under the pulsed laser pumping at fundamental wavelength of 1064 nm, the guided wave second harmonic generation (SHG) at 532 nm has been realized from the single and double cladding waveguides. Compared to the single-claddings (2.3 or 4.7%, depending on the diverse cladding diameters), the double cladding architecture has been found to be with enhanced SHG conversion efficiency (~5.1%).

Femtosecond laser written channel optical waveguide in Nd:YAG crystal

Abstract Low-repetition-rate (1 kHz) femtosecond laser inscription is used to fabricate channel waveguides in Nd:YAG crystal. Guiding occurs in the surroundings of the focal spot. End-to-end coupling measurements reveal the near-field intensity distribution of waveguides. The index profile reconstruction, mode analysis performed by the beam propagation method of these waveguides are presented. The waveguide written with 3.0 μJ pulse energy and 100 μm/s scan velocity shows strong guidance at 632.8 nm, and a propagation loss of about 0.5 dB/mm.

Ultrafast laser inscribed cladding waveguides in Nd:YAG crystal for mid-infrared wavelength

We report on tubular cladding optical waveguides fabricated in neodymium doped yttrium aluminum garnet (Nd:YAG) crystal by ultrafast laser inscription. The structure can support guidance at the wavelength of 4 μm for the TE and TM polarizations. The refractive index contrasts of the cladding waveguides for the two transverse polarizations were estimated to be ΔnTE≈−7.5×10−3 and ΔnTM≈−6.5×10−3. The propagation losses of the cladding waveguides at the wavelength of 4 μm were determined to be as low as ~0.7 dB/cm for the TE polarization and ~1.0 dB/cm for the TM polarization.

Femtosecond laser micromachined ridge waveguide lasers in Nd:YAG ceramics

We report on the fabrication of ridge waveguides in Nd:YAG ceramic by using femtosecond laser micromachining of the surface of a He ion implanted planar waveguide. Under optical pump of 808nm light, continuous wave waveguide lasers have been realized at 1.06μm at room temperature in the Nd:YAG ceramic ridge waveguide system, reaching a maximum output power of 46mW. The lasing threshold of ∼64.9mW and the slope efficiency of 42.5% are obtained for the ridge waveguide system, which shows superior lasing performance to the Nd:YAG ceramic planar waveguide.

Femtosecond-laser inscribed double-cladding waveguides in Nd:YAG crystal: a promising prototype for integrated lasers

We report on the design and implementation of a prototype of optical waveguides fabricated in Nd:YAG crystals by using femtosecond-laser irradiation. In this prototype, two concentric tubular structures with nearly circular cross sections of different diameters have been inscribed in the Nd:YAG crystals, generating double-cladding waveguides. Under 808 nm optical pumping, waveguide lasers have been realized in the double-cladding structures. Compared with single-cladding waveguides, the concentric tubular structures, benefiting from the large pump area of the outermost cladding, possess both superior laser performance and nearly single-mode beam profile in the inner cladding. Double-cladding waveguides of the same size were fabricated and coated by a thin optical film, and a maximum output power of 384 mW and a slope efficiency of 46.1% were obtained. Since the large diameters of the outer claddings are comparable with those of the optical fibers, this prototype paves a way to construct an integrated single-mode laser system with a direct fiber-waveguide configuration.

Proton or helium ion beam written channel waveguides in Nd:YAG ceramics

We report on the fabrication of channel waveguides in Nd:YAG ceramics, using either focused proton beam writing (PBW) or He beam writing (HeBW) techniques. Energies of ions used in the writing process were at 1MeV and 2MeV, respectively, with different writing fluence. High quality channel waveguides were produced in both H+ and He+ implanted regions. Characteristics of the waveguides were explored, and refractive index distribution of the waveguide was reconstructed.

Near-infrared lasers and self-frequency-doubling in Nd:YCOB cladding waveguides

A design of cladding waveguides in Nd:YCOB nonlinear crystals is demonstrated in this work. Compact Fabry-Perot oscillation cavities are employed for waveguide laser generation at 1062 nm and self-frequency-doubling at 531 nm, under optical pump at 810 nm. The waveguide laser shows slope efficiency as high as 55% at 1062 nm. The SFD green waveguide laser emits at 531 nm with a maximum power of 100 μW.

Optical properties of planar waveguide in Nd:YVO4 crystal formed by swift Kr8+ ion irradiation

We report on the fabrication of the planar waveguide in x-cut Nd:YVO4 laser crystal formed by 1.98GeV with the fluence of 2×1010ions/cm2 swift Kr8+ ion irradiation. The investigation of the absorption bands and the photoluminescence spectra demonstrates that the transmission properties of the bulk Nd:YVO4 crystal and the Nd3+ luminescence features have been preserved after ion irradiation. In Raman spectra, the peak positions and peak widths had no obvious change after ion irradiation. The irradiated cross section along with an accurate size measurement of the planar waveguide region buried beneath the surface of the crystal were observed by a microscope with transmitted polarized light. We also measured the near-field intensity distributions of the light in the waveguide by the end-face coupling method.

Buried waveguides in Nd:YLF crystals obtained by femtosecond laser writing under double line approach

In this paper, we present buried waveguides fabricated by fs laser writing in Nd3+ doped YLF crystal under double line approach (Miura et al. in Appl. Phys. Lett. 71:3329–3331, 1997). The waveguides were made by focusing two consecutive optical breakdown tracks (OBT) separated by about 20 μm. To make the optimal OBT, we focused the fs-laser pulses 200 μm below surface at intensities above the OB threshold for the material and controlled the writing speed. The guiding structures were fabricated by using a Chirped Pulse Amplification (CPA) femtosecond (fs) laser system. We chose the optimal writing parameters in order to obtain suitable waveguides, using around 3 μJ energy and writing speed from 15 to 50 μm/s. After optically exploring the waveguides by end-fire coupling, the guiding structures showed good optical performance. Guiding index profiles were retrieved from modal analysis by using BeamProp (RSoft) commercial software. This spatial distribution of the index increment, taking into account a lower refractive barrier on the OBT region plus the compressed region between the tracks, was obtained correctly fitting profiles modes.Finally, optical spectroscopy measurements were also performed in the waveguides. The results showed that the luminescence properties of Nd3+ ions are preserved in the waveguides compared with the values obtained for bulk.

Femtosecond laser inscribed cladding waveguides in Nd:YAG ceramics: Fabrication, fluorescence imaging and laser performance

We report on the fabrication of depressed cladding waveguide lasers in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) ceramics microstructured by femtosecond laser pulses. Full control over the confined light spatial distribution is demonstrated by the fabrication of high contrast waveguides with hexagonal, circular and trapezoidal configurations. The confocal fluorescence measurements of the waveguides reveal that the original luminescence features of Nd3+ ions are well-preserved in the waveguide regions. Under optical pump at 808 nm, cladding waveguides showed continuous wave efficient laser oscillation. The maximum output power obtained at 1064.5 nm is ~181 mW with a slope efficiency as high as 44%, which suggests that the fabricated Nd:YAG ceramic waveguides are promising candidates for efficient integrated laser sources.

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.

Continuous wave channel waveguide lasers in Nd:LuVO_4 fabricated by direct femtosecond laser writing

Buried channel waveguides in Nd:LuVO<4 were fabricated by femtosecond laser writing with the double-line technique. The photoluminescence properties of the bulk materials were found to be well preserved within the waveguide core region. Continuous-wave laser oscillation at 1066.4 nm was observed from the waveguide under ~809 nm optical excitation, with the absorbed pump power at threshold and laser slope efficiency of 98 mW and 14%, respectively.

Continuous wave waveguide lasers of swift argon ion irradiated Nd:YVO_4 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%.