Fabrication Of Magneto-Optical Glass Waveguide Based On Ion Implantation And Femtosecond Laser Ablation

The reverse propagation light in the optical circuit has a passive influence on the light source and the optical system,so it is necessary to isolate the reverse light.An optical isolator is an optical passive device that allows light to pass in one direction in the optical path.Its function is to isolate the reverse transmission light caused by various reasons,so as to improve the optical transmission efficiency.With the further de velopment of optical communication technology,people have put forward higher requirements on the performance of optical isolators including integration and functionalization.The research on the new generation of optical isolators has become a demand of optical communication systems.On the other hand,optical waveguides are the basic unit of integrated optics.Therefore,waveguide isolator that combines the characteristics of isolator and optical waveguide has gradually become a research hotspot.The performance of waveguide isolator depends on the performance of its waveguide structure.Therefore,it is very important to prepare a waveguide structure with excel ent performance.According to the geometric structure,optical waveguides can be divided into p lanar optical waveguides and channel optical waveguides.Ion implantation is an important technology for surface modification of materials,and is one of the important methods for fabricating waveguide structures.It has the advantages of extensive materia l applicability,ion energy and dose controllability,wide ion selectivity,and no pollution.So far,people have successfully fabricated optical waveguide structures on more than 100 optical materials by using ion implantation technology.In general,the ion implantation method can only fabricate planar optical waveguide structures that restrict the transmission of light in one direction.However,the channel optical waveguide structure can limit the transmission of light in two dimensions,which is more conducive to integration and has a broader application prospect.Today,the more commonly used methods for fabricating channel optical waveguide structures are mainly by combining ion implantation with micromachining techniques such as femtosecond laser ablation.The advantage of the method is that the preparation process is relatively simple and the fabricated waveguide structure has excellent performance.It is a kind of preparation technology with wide application prospect.Magneto-optical glass is one of the most commonly used Faraday rotating materials in optical isolators and circulators of optical communication systems and high-power laser systems due to its excellent characteristics?high Verdet constant,excellent uniformity,high damage threshold,a nd low nonlinear refractive index?.In this paper,magneto-optical glass is selected as the material to fabricate magneto-optical waveguides.The main content of this thesis is to prepare planar and channel optical waveguide structures in magneto-optical glass by combining ion implantation with micromachining techniques such as femtosecond laser ablation.The formation mechanism of the waveguide was explored through various optical characterization experiments,the cause of the refractive index change of t he waveguide was analyzed,and the optical transmission characteristics of the waveguide were studied.The research content provides experimental basis for preparing magneto-optical isolator.The main work is as follows:1. Fabrication of planar optical waveguide by helium ion implantation in magneto-optical glassA planar waveguide structure was fabricated in magneto-optical glass by using helium ion implantation with an energy of 400 ke V and a dose of 6.0×10¹⁶ ions/cm²,and the waveguide properties were optically characterized.The damage distribution of helium ion implantation was simulated by using SRIM 2013.The results show that the loss of nuclear energy is the main factor that causes the refractive index of the waveguide to change.The dark-mode spectrum of the waveguide shows that the waveguide has excited 4 modes in total,and the effective refractive index of the each waveguide mode is smaller than that of the substrate.It is a typical barrier-type waveguide structure,which can well limit the transmission of light.2. Fabrication of planar and channel optical waveguides by silicon ion implantation and femtosecond laser ablation in magneto-optical glassPlanar and channel optical waveguide structures were fabricated in magneto-optical glass by using silicon ion implantation with an energy of 6.0 Me V and a dose of 2×10¹⁵ ions/cm² combined with femtosecond laser ablation micromachining technology.The mechanism of heavy ion implantation to change the refractive index of the waveguide is determined by the loss of electronic energy and nuclear energy.The simulation results of SRIM and RCM show that the refractive index profile of the waveguide is a typical“well”+“barrier”type.This type of optical waveguide can well limit the transmission of light.We measured and simulated the near-field light intensity distribution of the waveguide,respectively.And the experimental results agree with the theoretical simulations.Measurements show that the propagation losses of the planar waveguide and the channel waveguide are 2.3 d B/cm and 3.4 d B/cm,respectively.3. Fabrication of planar and channel optical waveguides by dual-energy carbon ion implantation and femtosecond laser ablation in magneto-optical glassWe have fabricated a channel optical waveguide str ucture in the magneto-optical glass by ion implantation with?6+5.5?Me V carbon ions at a dose of?8+4?×10¹³ ions/cm² combined with femtosecond laser ablation micromachining technology.Double energy implantation can significantly increase the width of the optical barrier and greatly enhance the waveguide's ability to confine light.The near-field light intensity distributions of the waveguide structure were measured at the wavelengths of 532 nm and 976 nm,respectively.The results show that the channel waveguide structure has a better limitation on the optical transmission in the visible and near-infrared bands.