Phosphate Glass Waveguide Research Articles

Characterization of optical waveguides in Ce3+-doped phosphate glasses formed by He+ion implantation

In this work, the Ce3+-doped phosphate glass is carried out to fabricate the planar waveguides by the 400 keV He+ ion implantation with a dose of 6.0 × 1016 ions cm−2. The dark-mode spectrum of the waveguide at a wavelength of 632.8 nm is obtained by the prism coupling technique. The SRIM 2013 software is used to analyze the energy deposition induced by the ion implantation and the RCM is employed to reconstruct the refractive index profile of the planar waveguide. The end-face coupling technique is applied to the measurement of the propagation mode image of the waveguide at 632.8 nm. The Ce3+-doped phosphate glass waveguide has the potential for an integrated optical device.

Fabrication of an erbium–ytterbium-doped waveguide amplifier at communication wavelengths for integrated optics applications

Erbium–ytterbium-doped waveguide amplifiers provide a considerable gain at telecom wavelengths, low noise, nonlinearity, and compatibility with optical networks, making it an outstanding amplification module for telecommunication systems. This study reports on the fabrication of an optical waveguide amplifier for integrated optics. The signal can be amplified by using rare-earth dopings such as erbium (Er), which works at telecommunication wavelengths, i.e., 1.55 μm. Er-doped phosphate glass waveguides can be deposited using the sol–gel method, which is convenient for preparing active films on several substrates. The Er concentration was 1–2 × 1020/cm3. The confinement and the gain of the waveguide can be increased by reducing the width of the waveguide to 0.5 μm. In such a case, more than 1dB net gain can be achieved without additional pump power. The other material used as a dopant in optical amplifiers is ytterbium (Yb). For Er energy levels, a more significant pump intensity is necessary for inversion due to the limited absorption cross-section. This issue is solved by including a substance with a large absorption cross-section that transfers energy to Er. The Ag–Na ion exchange process is then used to fabricate the buried waveguide. In such a process, ions trade between the core material and the molten salt. Then, the waveguide is immersed in the molten salt. The fabricated waveguide has low loss, and a net gain of around 2 dB at a wavelength of approximately 1.55 μm in Er:Yb:Al: phospho silicate glass is achieved. The focus of the research is on the fabrication procedure (materials and methods) of the waveguide.

Guided-Wave Up-Conversion Luminescence in Er3+/Yb3+ Co-doped Phosphate Glass Waveguide Produced by Direct Femtosecond Laser Writing

We report on guided-wave up-conversion luminescence in femtosecond laser writing cladding waveguides in Er3+/Yb3+ co-doped phosphate glass. The waveguides were fabricated with 30-μm- and 100-μm-diameter of the guiding cores. The guiding properties of waveguides have been investigated at 633 nm by end face coupling of free space light and physical contact of fibers. The experimental and calculated results of propagating modal profiles and losses have proved favorable performances suitable to Gaussian mode field and multi-mode applications. Under the optical pump laser at 980 nm, the guided-wave up-conversion luminescence at visible light range has been realized through the waveguides.

Laser action from a femtosecond laser written Yb: phosphate glass waveguide

Single-transverse-mode active waveguide with circularly symmetric cross-section was written in Yb: phosphate glass using slit-shaped infrared femtosecond laser in low repetition rate regime. The refractive index profile reconstructed from the measured near field mode indicates that the waveguide is composed of a core with a depressed index cladding. The enhanced refractive index contrast due to the existence of cladding effectively supports waveguiding. Laser operating at 1030 nm was demonstrated when the waveguide was pumped at 976 nm. A maximum output power of 33 mW was obtained, resulting in a record slope efficiency of 18.5%.

Er3+/Yb3+ co-doped phosphate glass waveguides formed by the H+ ion implantation

The 400 keV proton implantation with a fluence of [Formula: see text] ions/cm2 was applied on the [Formula: see text] co-doped phosphate glass to fabricate a planar waveguide structure. The mode profile at the end face of the waveguide was measured by the end-face coupling technique. The energy loss profile of the energetic protons was calculated by the SRIM 2013. The refractive index distribution was simulated by the reflectivity calculation method. Based on these results, the formation theory of the planar waveguides was discussed through simulating the energy loss distribution and analyzing the reconstructed refractive index profile, which could be used for applications in the future integrated optical systems.

An infrared 2D Nd3+-doped phosphate glass waveguide formed by proton implantation and femtosecond laser ablation

The work reports on a concise investigation on the application of the proton implantation and the femtosecond laser ablation for the infrared two-dimensional waveguide formation in the Nd3+-doped phosphate glass. The Nd3+-doped phosphate glass was firstly irradiated by the 400-keVprotons with a fluence of 8.0 × 1016 ions/cm2 and then ablated by the femtosecond laser with 800-nm central wavelength, 1.0-kHz repetition rate and 120-fs pulse duration. The optical microscope image of the end-face was captured by an optical microscope for the implanted and ablated Nd3+-doped phosphate glass. The intervals between two neighbor grooves was 30 μm. The guiding characteristics of the 2D waveguide were measured by the end-face coupling technique. The results suggest that a 2D waveguide operating at 976 nm is fabricated in the Nd3+-doped phosphate glass. The hybrid fabrication technique opens a versatile and flexible way toward 2D photonic devices in the Nd3+-doped phosphate glass.

Optical properties of an Er3+-doped phosphate glass waveguide formed by single-energy H+ ion implantation

In this work, we report the fabrication of an optical waveguide by single-energy H+ ion implantation in the Er3+-doped phosphate glass. The ion implantation conditions are with energy of 0.4 MeV and a fluence of 8.0×1016 ions/cm2. The dark mode spectrum of the waveguide structure was measured by the prism coupling experiment. The refractive index change along with the penetration depth was fitted by using the reflectivity calculation method (RCM). Finally, the calculated near-field light intensity distribution shows superior waveguide properties, which demonstrates its promising potentials for compact optical integrated devices.

Near-infrared carbon-implanted Er3+/Yb3+ co-doped phosphate glass waveguides

The Er3+/Yb3+ co-doped phosphate (EYDP) glass waveguides operated at 1539 nm have been manufactured by using the implantation technique of carbon ions under the condition of 6.0 MeV energy and 5.0 × 1013 ions/cm2 fluence in this work. The ion implantation process was computed by means of the stopping and range of ions in matter. The dark-mode spectrum at 1539 nm of the waveguide was recorded by the method of the prism coupling measurement. The microscopic image of the fabricated structure was photographed by an optical microscope. It is the first step for the application of the waveguides on the base of EYDP glasses in optical-integrated photonic devices at near-infrared band.

Guiding properties of proton-implanted Nd3+-doped phosphate glass waveguides**Project supported by the National Natural Science Foundation of China (Grant Nos. 11405041 and 61475189) and NUPTSF, China (Grant Nos. NY214159, NY215007, and NY215113).

We report on the fabrication and properties of an optical waveguide in Nd3+-doped phosphate glass. The planar waveguide was obtained by 550-keV proton implantation with a dose of . The proton–glass interaction was simulated by the stopping and range of ions in matter (SRIM software). The characteristics of the waveguide including the refractive index profile and the near-field intensity distribution were studied by the reflectivity calculation method and the end-face coupling technique. The optical waveguide demonstrated multi-mode behavior at the wavelength of 632.8 nm. The propagation features of the proton-implanted Nd3+-doped phosphate glass waveguide shows its potential to operate as an integrated photonic device.

Waveguiding structures in Yb3+-doped phosphate glasses by double-energy proton and single-energy carbon-ion implantations

We report on the construction of waveguiding structures operating at 632.8 nm in the Yb3+-doped phosphate glass by two different techniques: carbon-ion implantation with a single-implant at an energy of 6.0 MeV and a dose of 5.0 × 1014 ions cm−2, and proton implantation with a double-implant of energies of (500 + 550) keV and doses of (1 + 2) × 1016 ions cm−2. The annealing treatments were performed at different temperatures ranging from 260 °C to 460 °C at internals of 50 °C. For the proton-implanted waveguide, the m-line spectrum and the refractive index profile were studied by a modal 2010 prism coupler and a reflectivity calculation method, respectively. The near field patterns in the both cases were recoded by an end-fire coupling system. The carbon- and proton-implanted Yb3+-doped phosphate glass waveguides can propagate guided modes after the continuous annealing, suggesting the applicability in the development of photonics devices.

Proton-implanted optical waveguides fabricated in Er3+-doped phosphate glasses

Er3+-doped phosphate glass is suitable to design and develop integrated photonic structures. Ion implantation is one of the most promising fabrication techniques for producing optical waveguides. In this work, we have combined Er3+-doped phosphate glass and ion implantation in order to improve the performances of waveguides. The proton-implanted Er3+-doped phosphate glass waveguides have been fabricated under implantation parameters with energies of (500 +550) keV and fluences of (1.0+2.0)×1016 ions/cm2. The guiding properties of the planar waveguide have been investigated at the wavelength of 632.8nm through the prism-coupling system and the end-face coupling arrangement. Irradiation-induced damage and refractive index modulation have been simulated by the stopping and range of ions in matter 2010 and the intensity calculation method, respectively. It is an important step to the fabrication of rare-earth-doped optical integrated devices.

Graphene Q-Switched Mode-Locked and Q-Switched Ion-Exchanged Waveguide Lasers

In this letter, we present the use of monolayer graphene saturable absorbers to produce Q-switched and Q-switched mode-locked operation of Yb and Yb:Er-doped phosphate glass waveguide lasers, respectively. For the 1535-nm-wavelength Yb:Er laser, the Q-switched pulses have repetition rates up to 526 kHz and contain mode-locked pulses at a repetition frequency of 6.8 GHz. The measured 0.44-nm bandwidth should allow pulses as short as $\sim 6$ ps to be generated. Maximum average output powers of 27 mW are obtained at a slope efficiency of 5% in this mode of operation. For the 1057-nm-wavelength Yb laser, Q-switched pulses are obtained with a repetition rate of up to 833 kHz and a maximum average output power of 21 mW. The pulse duration is found to decrease from 292 to 140 ns and the pulse energy increase from 17 to 27 nJ as the incident pump power increases from 220 to 652 mW.

Femtosecond laser written 16.5 mm long glass-waveguide amplifier and laser with 5.2 dB cm−1 internal gain at 1534 nm

A 16.5 mm long, heavily doped erbium–ytterbium phosphate glass-waveguide amplifier was fabricated by the femtosecond laser (fs-laser) inscription technique. The femtosecond laser inscription of waveguides was carried out at 500 kHz repetition rate using a 0.68 NA aspheric lens. The energy deposition profile in the dielectric material was initially simulated using a generalized adaptive fast-Fourier evolver (GAFFE) algorithm. The size and shape of the guiding structures were carefully controlled by the slit shaping technique to reduce the coupling losses, with achievable values down to less than 0.1 dB. Rigorous simulations of the response of the active waveguides were carried out to optimize their performance as optical amplifiers. A maximum of 8.6 dB internal gain at 1534 nm was obtained upon bidirectional laser pumping at 976 nm, leading to a gain per unit length of 5.2 dB cm−1. Laser action was also achieved for both ring and linear cavity configurations.

Concentration-dependent optimization of Yb3+/Er3+ highly-doped phosphate glass waveguide amplifiers and lasers using a microscopic statistical formalism

The dependence of the optimal performance of bidirectionally-pumped integrated amplifiers and lasers based on fs-laser written Yb3+/Er3+-codoped phosphate glass waveguides on the concentration of dopants is numerically analysed. A novel macroscopic rate-equation propagation model is used which considers concentration-dependent rates for the energy-transfer inter-atomic migration-assisted mechanisms. Optimal small-signal gain for an amplifier and output laser power for a ring laser are computed for various working conditions and broad dopants-concentration ranges. Optimal waveguide lengths are also analysed in detail. The large variations obtained in the dopants concentration required for optimal amplifier gain or output laser power and in the waveguide optimal length confirm that a previous rigorous numerical design is essential in order to achieve the optimized performance of these active devices.

Femtosecond laser writing of waveguides in zinc phosphate glasses [Invited

We have studied the relationship between the initial glass composition and the structural changes associated with laser-induced refractive index modification in a series of Er-Yb doped and undoped zinc phosphate glasses. White light microscopy and waveguide experiments are used together with Raman and fluorescence spectroscopy to characterize the structural changes. The correlation between Raman peak shifts and fluorescence from phosphorus–oxygen hole center (POHC) defects indicates that fs-laser writing results in a depolymerization of the phosphate glass network. The results also show that the exact glass composition should be taken into account when fabricating waveguide devices in phosphate glasses, in order to both expand the fs-laser processing conditions and maximize favorable morphological changes for 3-D photonic devices.

EFFECT OF TRANSMISSION FUNCTION OF CASCADED MULTILAYER MEDIUM THIN FILM FILTER ON Er–Yb CO-DOPED WAVEGUIDE AMPLIFIERS

Modeling and amplification of erbium–ytterbium co-doped phosphate glass waveguide amplifier with a cascaded multilayer medium thin film filter is investigated theoretically. This proposed filter consists of some different filtering unit cells with different central wavelength and bandwidth, and each cell can suppress certain peak gain at a specific wavelength. The intrinsical gain spectrum of amplifier is obtained by solving a set of rate and power propagation equations, the effect of transmittance spectrum of thin film filter on flattening gain is discussed, and the transmission function of cascaded multilayer medium thin film filter is obtained.

Evaluation of Optical Path Designing on 4x4 Cm<sup>2</sup> Er<sup>3+</sup>/Yb<sup>3+</sup> Doped Phosphate Glass Waveguide Substrate

To achieve high-gain C-band waveguide amplifiers with integrated configuration, bent channel structures (S-, U-, and F-bend) based on buried Er3+/Yb3+ codoped phosphate glass waveguide channel fabricated by field-assisted annealing (FAA) have been designed in a 4´4 cm2 substrate. Using simulated-bend method, the optimal radius for the curved structure is derived to be 1.00 cm with loss coefficient of 0.0045 dB/cm. In the wavelength range of 1520-1575 nm, obvious gain enhancement for the bent structure waveguides is anticipated, and for the F-bend waveguide, the net gain at 1534 nm wavelength is derived to be 43.95 dB, which is much higher than the value of 26.67 and 13.20 dB in the U- and S-bend waveguides, respectively, and over three times higher than that of the straight one. The simulation results indicate that the bent structure designing is beneficial in obtaining high signal gain in buried Er3+/Yb3+ codoped phosphate glass waveguides, which lays the foundation for the further design and fabrication of integrated devices.

Bent channel design in buried Er<sup>3+</sup>/Yb<sup>3+</sup> codoped phosphate glass waveguide fabricated by field-assisted annealing

Bent waveguide structures (S-, U-, and F-bend) based on buried Er 3 + /Yb 3 + codoped phosphate glass waveguide channel fabricated by field-assisted annealing have been designed to achieve high-gain C-band integrated amplification. Using a simulated-bend method, the optimal radius for the curved structure is derived to be 0.90 cm with loss coefficient of 0.02 dB/cm, as the substrate size is schemed to be 4×3 cm 2 . In the wavelength range of 1520 to 1575 nm, obvious gain enhancement for the bent structure waveguides is anticipated, and for the F-bend waveguide, the internal gain at 1534-nm wavelength is derived to be 41.61 dB, which is much higher than the value of 26.22 and 13.81 dB in the U- and S-bend waveguides, respectively, and over three times higher than that of the straight one. The simulation results indicate that the bent structure design is beneficial in obtaining high signal gain in buried Er 3 + /Yb 3 + codoped phosphate glass waveguides, which lays the foundation for further design and fabrication of integrated devices.

Assessment of Rayleigh and non-Rayleigh Contributions to the Transmission Losses in fs-Laser Written Er/Yb-Codoped Phosphate Glass Waveguides

Assessment of Rayleigh and non-Rayleigh Contributions to the Transmission Losses in fs-Laser Written Er/Yb-Codoped Phosphate Glass Waveguides

Design and Simulation of Broadband IR integrated Waveguide Amplifiers with Long - Period Waveguide Grating Filter

A novel broadband IR integrated Er-Yb codoped phosphate glass waveguide amplifier with a long-period waveguide grating is proposed. The long-period waveguide grating, which is used as a gain equalizer, is directly fabricated in the waveguide. The amplifier model is based on propagation and population-rate equations and includes both uniform and pair-induced up-conversion mechanisms. It is solved numerically by combining overlapping integral and Runge-Kutta(RK) algorithm. The intrinsical gain spectrum of the proposed amplifier is obtained by solving a set of rate and power propagation equations and, the deleterious gain peaking is reduced by the long-period waveguide grating filter. The effects of transmission spectrum of the proposed long-period grating on flattening gain are discussed. An average gain ~ 20dB between 1532 nm and 1565 nm with gain difference of < 3dB is achieved.