Dark Mode Spectra Research Articles

Optical waveguides in magneto-optical glasses fabricated by proton implantation

Planar waveguides in magneto-optical glasses (Tb3+-doped aluminum borosilicate glasses) have been produced by a 550-keV proton implantation at a dose of 4.0×1016ions/cm2 for the first time to our knowledge. After annealing at 260°C for 1.0h, the dark-mode spectra and near-field intensity distributions are measured by the prism-coupling and end-face coupling methods. The damage profile, refractive index distribution and light propagation mode of the planar waveguide are numerically calculated by SRIM 2010, RCM and FD-BPM, respectively. The effects of implantation on the structural and optical properties are investigated by Raman and absorption spectra. It suggests that the proton-implanted Tb3+-doped aluminum borosilicate glass waveguide is a good candidate for a waveguide isolator in optical fiber communication and all-optical communication.

KTiOPO4double barrier optical waveguides produced by Rb+-K+ion exchange and subsequent He+-ion irradiation

We report on the fabrication and characterization of KTiOPO4 optical waveguides formed by Rb+-K+ ion exchange in high-purity RbNO3 melt at 340°C for 90 min and subsequent He+-ion irradiation at energy of 500 keV and fluence of 3×1016 ions/cm2. The irradiation of KTiOPO4 crystals with He+ ions was simulated using the stopping range of ions in matter (SRIM’2006) software. The dark mode spectra of the samples were measured with the prism coupling method. The reconstructed refractive index profiles of the planar waveguide show a barrier in the middle of the guiding region, and a refractive index enhancement region on each side of the barrier, indicating the formation of a double waveguide.

Active waveguides by low-fluence carbon implantation in Nd3+-doped fluorophosphate glasses

A planar waveguide in the Nd[Formula: see text]-doped fluorophosphate glass is fabricated by a 6.0 MeV C[Formula: see text] ion implantation at a low-fluence of [Formula: see text] ions/cm2. The fluence is close to that in semiconductor industry. The dark mode spectra are recorded by a model 2010 prism coupler. The energy losses during the implantation process and the refractive index profile of the waveguide are simulated by the SRIM 2010 code and the reflectivity calculation method (RCM), respectively. The near-field light intensity profile and the propagation loss of the waveguide are measured by an end-face coupling system. The two-dimensional (2D) modal profile of transverse electric (TE) mode for the fabricated waveguide is calculated by the finite difference beam propagation method (FD-BPM). The results of microluminescence and optical absorption reveal that the spectroscopic characteristics of the Nd[Formula: see text]-doped fluorophosphate glass are nearly unaffected by the carbon ion implantation process. This work suggests that the carbon-implanted Nd[Formula: see text]-doped fluorophosphate glass waveguide is a promising candidate for integrated active devices.

Influences on proton exchange by He ion implantation in LiNbO_3

This paper concerns the influence on proton exchange in the modified lithium niobate by 200 keV He ion implantation at liquid nitrogen temperature. The Rutherford backscattering/channelling spectra revealed the damage undergoing the different conditions treatment. Experimental data showed that there were some influences on proton exchange due to the damage and defects induced by He ion implantation. The planar waveguides were fabricated by proton exchange combined with He ion implantation. The dark mode spectra were observed and the near-field intensity distribution of one waveguide is detected. The estimated propagation loss was 2.0 dB/cm at 633 nm.

Planar waveguides in Yb3+-doped tellurite glasses fabricated by ion implantation of oxygen

A planar waveguide is demonstrated in the Yb 3+-doped tellurite glass, using (5+6) MeV O 3+ ion implantation with doses of (4+8)×1014 ions/cm2. The implantation process of O 3+ ions into the Yb 3+-doped tellurite glass is simulated by the stopping and range of ions in matter (SRIM) 2010 code. The dark-mode spectra are measured by the prism-coupling system at λ = 632.8 nm. The reflectivity calculation method and the finite-difference beam propagation method are used to calculate the refractive index profile and the modal profile of transverse electric (TE) mode of the fabricated waveguide, respectively. The absorption spectra show that the transmission properties are not affected by the waveguide fabrication process.

Fabrication and annealing optimization of oxygen-implanted Yb3+-doped phosphate glass planar waveguides

Abstract Optical planar waveguides in Yb3+-doped phosphate glasses are fabricated by (5.0+6.0) MeV O3+ ion implantation at fluences of (4.0+8.0)×1014 ions/cm2. The annealing treatment is carried out to optimize waveguide performances. The prism-coupling and end-face coupling methods are used to measure the dark-mode spectra and near-field intensity distributions before and after annealing at 350 °C for 60 min, respectively. The refractive index profile of the planar waveguide is obtained based on the reflectivity calculation method. The micro-Raman spectrum of the waveguide is in agreement with that of the bulk, exhibiting possible applications for integrated active photonic devices.

The refractive index distributions of KTP crystal waveguides formed with He-ions at high fluences and low energy

The 300keV He+ ions have been implanted into z-cut KTP crystals with fluences of 4×1016, 6×1016, 8×1016 and 10×1016ions/cm2. The Rutherford back scattering spectrometry (RBS)/channelling spectra of KTP crystals and the dark-mode spectrum have been measured. According to the multiple scattering formulae of Feldman and Rodgers, the damage profiles of z-cut KTP crystals have been calculated and extracted. The relations between the damage ratio, fluence and the ion-implanted depth have been established. The refractive index profiles over depth have been calculated, which are very close to the real distribution in waveguide.

Optical properties of Yb3+-doped silicate glasses waveguides formed by low-dose oxygen ion implantation and effects of annealing

The planar waveguide, to our knowledge, has been firstly fabricated in the Yb3+-doped silicate glass by 6.0MeV O3+ ion implantation at a dose of 6×1014ions/cm2. The guiding properties are characterized by the prism-coupling and end-face coupling methods with a He–Ne beam. The dark-mode spectra and near-field intensity distribution are measured before and after annealing at 250°C for 1h in air. The results indicate that the thermal treatment can enhance the propagation properties with preserving the effective refractive indices well. The refractive index profile of the planar waveguide is reconstructed by the reflectivity calculation method, which shows a typical “enhanced well+optical barrier” distribution. The SRIM’2006 code is carried out to simulate the energy loss during the implantation in order to obtain a better understanding of the waveguide formation.

Optical waveguide with homogeneous refractive index profile in LiNbO 3 by double-low-energy Oxygen ion implantation

We report on the formation of the planar waveguide by 550 keV O ion followed by 250 keV O ion implantation in lithium niobate (LiNbO 3), at fluences of 6 × 10 14 ions/cm 2 and 3 × 10 14 ions/cm 2, respectively. The Rutherford backscattering/channeling spectra have shown the atomic displacements in the damage region before and after annealing. A broad and nearly homogeneous damage layer has been formed by double-energy ion implantation after annealing. Both the dark mode spectra and the data of refractive index profile verified that the extraordinary refractive index was enhanced in the ion implanted region of LiNbO 3. A homogeneous near-field intensity profile was obtained by double-low-energy ion implantation. There is a reasonable agreement between the simulated modal intensity profile and the experimental data. The estimated propagation loss is about 0.5 dB/cm.

Planar waveguides in magnesium doped stoichiometric LiNbO 3 crystals formed by MeV oxygen ion implantations

The planar waveguides were formed in magnesium doped stoichiometric LiNbO 3 crystals by means of 4.5 MeV oxygen ion implantations at different fluences. The dark mode spectra were measured by the prism coupling method. The annealing behaviors of the formed waveguides were characterized by a series of annealing treatments. The Rutherford backscattering/channeling technique was used to investigate the damage produced by the ion implantation.

Crystal growth and characterization of RbTi1−x−yYbxNbyOPO4/RbTiOPO4 (001) non-linear optical epitaxial layers

In this paper we report the growth of RbTi1−x−yYbxNbyOPO4/RbTiOPO4 epitaxial layers by the liquid phase epitaxy method and discuss their structural and optical characterization. The layers were grown on (001) oriented substrates because this plane contains the phase-matching direction for Yb3+ type-II second-harmonic generation. In RbTi0.971Yb0.015Nb0.014OPO4/RbTiOPO4 epitaxial layers we obtained enough contrast of refractive indices (Δnz = 0.007 at 632.8 nm) to guide the light in TM polarization. The maximum Yb3+ concentration obtained in these layers was 1.43 × 1020 atoms per cm3, which may be suitable for laser action. The lattice mismatch between the epitaxial layers and the substrates was low enough to obtain high quality epitaxial layers. Confinement of the light at 532 and 632.8 nm was demonstrated and there was good agreement between theoretical calculations, dark-mode spectra and modes of propagation.

Waveguiding demonstration on Yb:Nb:RbTiOPO 4/RbTiOPO 4(0 0 1) epitaxies grown by LPE

The present paper shows epitaxial layers grown by liquid phase epitaxy of RbTiOPO 4 doped with Yb 3+ on substrates of RTP. The layers were grown on (0 0 1) plane, which contains the phase matching direction for type-II second harmonic generation for the Yb 3+ emission wavelength range. The layer guides polarized light parallel to c crystallographic direction. A 10 m-thickness epitaxial layer guides five modes which had been observed by dark-mode spectrum. The measured losses were about 0.7 dB/cm.

The array waveguides formed in LiNbO 3 crystal by oxygen-ion implantation

We have proposed and discussed an array channel waveguide with a period of 11 μm, which was fabricated using direct multiple-energy oxygen-ion implantation at a total dose of 6 × 10 14 ions/cm 2 in z-cut LiNbO 3 crystal, for the first time, to our knowledge. The extraordinary refractive index profile experiences positive changes with respect to the bulk according to the dark mode spectra measurement results. The coupling effect of light propagating in the array was observed, and the numerically calculated modal distributions were in good agreement with the experimental results. This design may be useful for the formation of discrete spatial solitons.

Green light waveguide demonstration on Y b:Nb:RbTiOPO4/RbTiOPO4 epitaxial layers

In this paper epitaxial layers of RbTiOPO4 doped with Y b3+ on substrates of RbTiOPO4 have been grown by Liquid Phase epitaxy on the (001) plane, which contains the phase matching direction for Type II Second Harmonic Generation for the Y b3+ emission wavelength range. These layers can guide polarized light parallel to the c crystallographic direction. A 5μm-thickness epitaxial layer can guide 3 propagation modes as it has been observed by the dark-mode spectrum. The sample was polished in both end-faces to visualize the TM modes of the waveguides. The near field pattern was recorded by a CCD camera, using a green diode laser at a wavelength of 532nm, coupled into, and out from the waveguide using two microscope objectives. The demonstration of good guiding at a wavelength of 532nm in Y b:Nb:RbTiOPO4 waveguides is one of the important steps to obtain Self Frequency Doubling laser waveguides.

Monoclinic double tungstate lattice matched epitaxial layers for integrated optics applications

In this work we report on the activation of KY 1−x−yGdxLuy(WO4)2 lattice matched epitaxial layers with Er3+ and Tm3+ ions. The epilayers posses low enough lattice mismatch as well as high enough refractive index contrast with respect to the KY (WO4)2 substrates, which are key parameters for the fabrication of high quality optical waveguides. A structural study revealed that there are two types of lattice matched KY 1−x−yGdxLuy(WO4)2 compositions, one with a negative lattice mismatch, - 0.53×10−3, corresponding to KY 0.58Gd0.22Lu0.20(WO4)2, and the second one with a positive lattice mismatch, 0.55×10−3, which corresponds to KY 0.75Gd0.18Lu0.07(WO4)2. However, the refractive indices corresponding to the first one were greater than those of the second composition. We then chose the composition with a negative lattice mismatch for doping with Er3+ and Tm3+ active ions, both with percentages of 1% at. and 3% at. Epitaxial growth of the active lattice matched layers on b oriented KY (WO4)2 substrates was obtained without loosing structural quality compared with the passive compositions. Waveguiding demonstration was observed by recording the dark mode spectra at different wavelengths.

Cs+-K+ Exchange in Z-Cut KTiOPO4 Crystal Covered with Chromium Masking Layer

Cs+-K+ ion exchanges are performed on z-cut KTiOPO4 crystals with chromium coating covered. The temperature of ion exchange is 430°C, and the time range from 15min to 30 min. The dark mode spectra of the samples are measured by the prism coupling method. The channel structures on the samples are observed by a microscope and the near field pattern of the channel waveguides are measured by the end-fire coupling method. The refractive index of the samples increases and the increments at surface are modulated due to the existence of Cr film. In the region covered by Cr film, the refractive index of the samples at the surface increases dramatically in a shallow layer. The results of energy dispersive x-ray spectra indicate that in the region covered with Cr film, Cr ions participate in the ion exchange process, and enhance the refractive index. The results may provide a possibility that achieves index enhancement and Cr doping synchronically.

Ion exchange in KTiOPO_4 crystals irradiated by Copper and Hydrogen ions

Cs(+)-K+ ion exchanges were produced on KTiOPO4 crystals which is prior irradiated by Cu+ can H+ ions. The energy and dose of implanted Cu+ ions are 1.5 MeV and 0.5 x 10(14) ions/cm2, and that of H+ are 300 keV and 1 x 10(16) ions/cm2, respectively. The temperature of ions exchange is 430 degrees C, and the time range from 15 minutes to 30 minutes. The prism coupling method is used to measure the dark mode spectra of the samples. Compared with results of ion exchange on the sample without irradiations, both the number of guided mode and its corresponding effective refractive index are decreased. The experimental results indicate that the ion exchange rate closely related with the lattice damage and the damage layers formed in the depth of maximum nuclear energy deposition act as a barrier to block the ions diffuse into the sample and the concentration of defects can modify the speed of ion exchange..

BURIED PLANAR WAVEGUIDE IN KTiOPO4 FORMED BY Cs+ ION EXCHANGE AND Si+ ION IMPLANTATION

Buried planar waveguide was produced by Cs +– K + ion exchange and Si + ion implantation in z-cut KTiOPO 4 (KTP) single domain crystals. The dark mode spectra of the waveguide were obtained by the prism-coupling method. The refractive index profiles of the Cs +– K + ion exchanged sample were reconstructed using the inverse Wenzel–Kramers–Brillouin (iWKB) method and the analysis of the refractive index profile has shown an exponential distribution in the exchange layer. The Si + ions implanted into the Cs +– K + exchange sample with the energy of 550 keV at a dose of 1.0×1015 ions/cm2 at room temperature to form a buried planar waveguide structure. The program code TRIM'98 (transport of ions in matter) is used to simulate the implantation process. The near field patterns of propagation light in buried waveguide was studied by the end-coupling method.

Reconstruction of extraordinary refractive index profiles of optical planar waveguides with single or double modes fabricated by O2+ ion implantation into lithium niobate

A method named intensity calculation method (ICM), which is based on beam propagation method (BPM) and image processing, was carried out to reconstruct the extraordinary refractive index profile (RIP) of single-mode planar waveguide in lithium niobate (LiNbO3), which was fabricated by multi-energy megaelectron-volt (MeV) O2+ ion implantation. In addition, it has been proved reasonable that the alternation of extraordinary refractive index induced by ion implantation into LiNbO3 is mainly due to the degradation of polarization and reduction of material physical density. As a result, the possible extraordinary RIP of the double-mode planar waveguide could be reconstructed using BPM according to such a hypothesis and the calculated guiding mode values. The end-fire coupling and m-line arrangements were carried out to obtain the near-field modal patterns and dark-mode spectra of waveguides, respectively.

Optical waveguide in stoichiometric lithium niobate formed by 500 keV proton implantation

We report on the fabrication of planar waveguide in stoichiometric lithium niobate by 500 keV proton implantation with a dose of 1x10(17) ions/cm(2). The formation of n(e) enhancement planar waveguide in the crystal was disclosed by the dark mode spectra and the subsequent endface coupling measurement. The absorption spectra show that the postannealing treatments above 400 masculineC temperature can remove the color centers induced by implantation efficiently. The propagation loss and near-field profiles of the planar waveguide were obtained with an end-face coupling system.