Optical waveguides are known as important information transmission carriers in the information era[
Acta Photonica Sinica, Volume. 49, Issue 4, 0423001(2020)
Near-infrared Properties of Optical Planar Waveguides Formed by H+ Ion Implantation in Yb3+-doped Phosphate Glasses
The Yb3+-doped phosphate glass waveguides by the hydrogen-ion implantation under the condition of energies of (0.5+0.55) MeV and doses of (1.0+2.0)×1016 ions/cm2 were fabricated, and characteristics of the waveguide were studied in the near-infrared band. The change of refractive index after the implantation was measured by the prism coupling method, which corresponded well with the calculated effective refractive index by the reflectivity calculation method. The formation theory of the ion-implanted planar waveguides was discussed through simulating the vacancy distribution induced by the irradiation. The propagation mode of light in the waveguide was simulated by using the FD-BPM, which suggested that the near-infrared waveguide structure could be fabricated by irradiating the Yb3+-doped phosphate glass with the energetic hydrogen ions.
0 Introduction
Optical waveguides are known as important information transmission carriers in the information era[
Yb3+-doped Phosphate Glass (YDPG) is intriguing for fabricating waveguides, owing to its excellent material features. Yb3+-doped phosphate glass has long fluorescence lifetime, which is conducive to energy storage. The thermal load of Yb3+-doped phosphate glass is relatively low. Even at high pump power density, the temperature change in the material is small. Moreover, the Yb3+ level structure is relatively simple, so there is no excitation state absorption at the pump wavelength and the signal wavelength. Optical conversion efficiency is very high[
Although researchers have applied ion implantation techniques to fabricate optical waveguides on Yb3+-doped phosphate glasses[
1 Experiments
The Yb3+-doped phosphate glass was prepared by the melt-quenching technique at the Xi′an Institute of Optics and Precision Mechanics of Chinese Academy of Science. After cutting, grinding and polishing, several glass samples with sizes of 10 mm×5 mm×2 mm were chosen for the property measurement and waveguide preparation. The refractive indices of the YDPG are 1.534 4 at 632.8 nm and 1.521 0 at 1 539 nm, respectively.
In order to form an optical waveguide structure, H+ ions with energies of (500+550) keV were implanted into one of the polished surfaces (10 mm×5 mm) of the Yb3+-doped phosphate glass at room temperature according to the desired thickness of the optical waveguide, as shown in
Figure 1.Schematic of the proton implantation into the Yb3+-doped phosphate glass and the inset is the glass photograph
The ion-implanted Yb3+-doped phosphate glasses were optically measured by using Model 2010 prism coupler to study the dark mode properties. The prism code was 1 004.4 and the refractive index of the prism was 1.934 6 at 1 539 nm. A semiconductor laser with a wavelength of 1 539 nm was equipped in the prism-coupling system to serve as a working source. During the measurement process, the laser beam with a wavelength of 1 539 nm was coupled into the waveguide layer through the bottom of the prism. Then, the guided mode was excited and the intensity of the reflected light was reduced. Therefore, a relationship curve between the effective refractive index of the incident light and the intensity of the reflected light was obtained. The refractive index corresponding to the dip in the curve was the effective refractive index of the guided mode.
2 Results and discussion
The dark-mode curve was measured by the prism coupling system, which can calculate the refractive index of the propagation mode in the waveguide.
Figure 2.Vacancy profile as a function of irradiation depth for (500+550) keV protons implanted into the YDPG
Figure 3.Dark-mode curve of the YDPG waveguide at 1 539 nm
It is essential to know the profile of the refractive index in a waveguide structure, because that the refractive index distribution plays a decisive role in the propagation characteristics of an optical waveguide. However, the refractive index profile is difficult to measure directly. Therefore, there are several different techniques for calculating the refractive index profile, such as the parameterized index profile reconstruction[
Figure 4.Refractive index distribution of the H+-ion implanted Yb3+-doped phosphate glass waveguide at the wavelength of 1 539 nm
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The Finite-difference Beam Propagation Method(FD-BPM) is one of the most effective techniques for dealing with the propagation of light waves in optical waveguide devices[
Figure 5.Near-field intensity distribution of the YDPG
3 Conclusion
The near-infrared planar waveguide in the Yb3+-doped phosphate glass was produced by the H+ ion implantation. The waveguide contains three modes from the m-line curve measured by the prism-coupling system. The refractive index profile of the waveguide is a well-known "barrier"-type model. The refractive index difference between the waveguide layer and the optical barrier was on the order of 10-2 according to the RCM-simulation. The mode profile calculated by the FD-BPM suggests that the waveguide can confine the light with a wavelength of 1 539 nm.
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Jing-yan LÜ, Hai-tao GUO, Jun XU, Chun-xiao LIU. Near-infrared Properties of Optical Planar Waveguides Formed by H+ Ion Implantation in Yb3+-doped Phosphate Glasses[J]. Acta Photonica Sinica, 2020, 49(4): 0423001
Category: Optical Devices
Received: Nov. 1, 2019
Accepted: Dec. 16, 2019
Published Online: Apr. 24, 2020
The Author Email: LIU Chun-xiao (chunxiaoliu@njupt.edu.cn)