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Study On Er3+-Yb3+ Co-doped Polymeric Planar Optical Waveguide Amplifiers Fabricated On Si Substrate

Posted on:2011-01-09Degree:DoctorType:Dissertation
Country:ChinaCandidate:C ChenFull Text:PDF
GTID:1118360305453636Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
The 21st century will be the century of light, which has become the consensus of the people. Nowadays, the widespread use of optical communications networks has greatly changed people's way of life. In the process of optical communication, there is the inevitable loss of light energy, thus the erbium-doped fiber amplifiers in long-distance transmission has been widely applied. However the erbium-doped fiber amplifiers are still too bulky and costly to be used in local area and access networks for the fiber to the home configuration in the future. Following these demands, compact and cost-effective integrated erbium -doped waveguide amplifiers (EDWAs) are desirable. On the other hand, the photon computer is a hot direction in the development of future computer technology. Now people are studying on various photonic devices based on silicon substrate which can replace the electronic components. The optical loss in the application of these photonic devices will finally bring trouble. Therefore, the silicon-based waveguide amplifier integrated with these photonic chips will be able to effectively compensate optical loss and improve the efficiency of optical transmission. Based on the above two points, together with organic polymer material has a cheap, good mechanical properties, as well as the advantages of easy preparation of waveguide, we have chosen silicon-based organic polymer optical waveguide amplifier as the object of our study.This thesis's main tasks are as follows:1. Hydrothermally synthesized ErYb(DBM)3(MA) complex monomer and ErYb(DBM)3(MA)/PMMA-GMA polymer. The absorption spectra and luminescence spectra of complex powder were measured. The spectrum consists of seven absorption bands of Er3+, corresponding to the transitions from the ground state 4I15/2 to the excited states: 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2 and 4I13/2 was obtained, as well as one absorption band of Yb3+, corresponding to the transition from the ground state 2F7/2 to the excited state 2F5/2. A test system of PL spectra was set up and the near-infrared photoluminescence (NIR PL) spectrum of the powder excited at 976 nm at room temperature is obtained. The full-width-at-half-maximum (FWHM) of the emission spectrum around 1530 nm is 83 nm, which is a very wide emission spectrum compared to erbium-doped inorganic materials. This will help produce a large gain-bandwidth. The film-forming ability, refractive index, and film thickness were characterized. A rectangular optical waveguide amplifier was fabricated with spin-coating, steaming aluminum, photolithography, developing and reactive ion etching method.(RIE). The shape of waveguide showed smooth. A set of waveguide device coupling test system was set up and well near-field spot was obtained. A relative gain of 1.2dB was obtained in a 1.5cm long waveguide. (0.8dB/cm)2. A solution-processable erbium-ytterbium co-doped complex was synthesized, which can be soluble in cyclopentanone and then used to spin-coat thin-film waveguide directly. The concentration of erbium was as high as 10.8wt%. The parameters of the material were characterized. The typical characteristic absorption spectra and photoluminescence spectra of complex powder and film as well as a high FWHM (80nm) were obtained. The influence of ytterbium ion concentration to the photoluminescence spectra was studied. The best 3:2 ratio of erbium: ytterbium ion concentration was obtained by measuring the photoluminescence intensity of different erbium ytterbium ion content. The erbium ion concentration of the complex is too high, which lead to the failure of etching. We carried out the XPS spectroscopy on the surface of the complex film, and found out the reasons why the film can not been etched. Therefore, we designed a type of embedded waveguide structure and fabricated optical waveguide amplifier with two kinds of materials as cladding layer, respectively. The near-field spot and optical gain of embedded waveguide with the PMMA-GMA and SU-8 as the cladding layer were measured use the fiber-waveguide coupling test system and gain test system, respectively. A well near-field optical spot was showed. The relative gain of 5.53dB/cm and 3.47dB/cm were obtained when the cladding layer was PMMA-GMA and SU-8, respectively. Then the difference of the gain characteristics between the organic optical waveguide amplifier and the inorganic optical waveguide amplifier has been studied. The reason why the relative gains reach a maximum value was due to the weak thermal stability of the organic polymer compared with the inorganic matrix. The damage on the polymer waveguide and complex powder after increasing the power of pump laser to 160mW for a while (about 5minute) was found in the experiment. We got a conclusion that the single-mode waveguide confine the light much better than the multi-mode waveguide by calculating the modes in the waveguide with PMMA-GMA and SU-8 as the cladding layer respectively and simulate the optical transmission in the two kinds of waveguide with BPM software.3. Oleic acid modified LaF3:Er,Yb nanoparticles were synthesized. A kind of organic-inorganic hybrid material was synthesized with sol-gel method. Then oleic acid modified LaF3:Er,Yb nanoparticle doped organic inorganic hybrid material(OIHM) have been synthesized. The concentration of erbium was as high as 15.6 wt%. The morphology and dispersion of the oleic acid modified LaF3:Er,Yb nanoparticle was analyzed by Transmission Electron Microscopy(TEM) and found that the size of LaF3:Er,Yb nanoparticle was around 5~10nm, without significant aggregation. The film of LaF3:Er,Yb nanoparticle/OIHM was analyzed by Microscope and Atomic Force Microscopy and found that the surface of film was very smooth and suitable for waveguide preparation. The typical characteristic absorption spectra and photoluminescence spectra of LaF3:Er,Yb nanoparticle/OIHM film as well as a high FWHM (82nm) were obtained. An embedded optical waveguide amplifier was fabricated with this material as core layer by RIE progress. The shape of waveguide showed smooth. After polishing the device, the couple loss was reduced 17.3dB by compare the output optical power before and after polishing. When the pump power was 133.6mW, the maximum relative gain of 4.14dB,3.91dB and 3.70dB were obtained in a 2.9cm-long waveguide when the input signal were 0.2mW,0.5mW and 1mW, respectively, which showed that the gain of small input signal was bigger. The up-conversion phenomena have been investigated. The possible up-conversion process in the LaF3:Er,Yb nanoparticle/OIHM waveguide amplifier were discussed.4. The rectangular waveguide of SU-8 was fabricated by using wet etching. An excelent shape of SU-8 rectangular waveguide was observed by Microscope and Scan Electron Microscope. The near-field optical spot of rectangular waveguide was measured by using the fiber-waveguide coupling test system. A well near-field optical spot was showed. A 33-channel arrayed waveguide grating(AWG) was fabricated use SU-8, which could adjust the output channel by adjusting the wavelength of input signal. A variety of ways were tried to fabricated waveguide which used ErYb(DBM)3 -(MA)/SU-8 as the core material. Finally, an embedded waveguide was fabricated successfully. A waveguide device was fabricated by using ion-exchange method. The number of mode under different ion exchange time was measured using a prism coupling device. The effective refractive index of the waveguide was calculated. The optimized time of ion exchange is 15 minutes. The surface of the glass waveguide was observed under a Microscope, which showed that the waveguides were complete and the size meet the design requirements. The near- field optical spot of glass waveguide was measured use the fiber-waveguide coupling test system. A well near-field optical spot was showed. The typical characteristic absorption spectra and photoluminescence spectra of erbium-ytterbium co-doped phosphate glass as well as a lower FWHM (42nm) were obtained. The gain characteristiccs of phosphate glass waveguide amplifier were measured. The maximum relative gain was 2.5dB in a 2.6-cm-long waveguide when the input signal was 0.1mW@1550 nm and the input pump laser was 180mW@980nm. (i.e. 0.96dB/cm) The relative gain increased with the pump power increased, which agreed with the theory.This thesis's main innovative points are as follows:1. Took advantage of the higher absorption cross section of ytterbium in the 980nm, we added the ytterbium ions when synthesized the active material, which enhanced the intensity of photoluminescence obviously.2. With a view to the difficulty for the erbium ions doped into organic polymers directly, we designed several ways to increase the concentration of erbium ions in the polymer. The first way is to prepare erbium ytterbium co-doped complex by hydrothermal synthesis method, with complex wrapped up the erbium ions, and then doped into the PMMA-GMA. The concentration of erbium ions was improved to 1wt%, which was closed to the doping level of inorganic waveguide amplifier. The second way is to synthesize a solution-processable erbium-ytterbium co-doped complex, which is soluble in organic solvents (cyclopentanone for example). The solution can be used to spin coating and fabricate waveguide directly. The concentration of erbium ions was as high as 10.8wt%. The third way is to synthesize Oleic acid modified LaF3:Er,Yb nanoparticles doped organic-inorganic hybrid materials, in which the concentration of erbium ions was as high as 15.6wt%. This is the highest concentration of erbium ions in organic polymer so far as reported.3. The optical properties of these three kinds of erbium ytterbium co-doped active material were tested. The typical absorption and photoluminescence spectra of these three materials were obtained, which were the premise of the optical gain. The reason for the active material with high concentration of erbium ions difficult to be reactive ion etched was studied. Then we designed two kinds of structure as the rectangular waveguide and the embedded waveguide, as well as two fabrication processes. We fabricated the two kinds of waveguide and obtained good morphology. The relative optical gains of 0.80 dB/cm,5.53 dB/cm and 1.43 dB/cm of these three erbium ytterbium co-doped materials were obtained respectively.4. We studied on the erbium ytterbium co-doped SU-8 material and tried to fabricate the AWG device, which showed the possibility of integration between EDWA and AWG. A kind of embedded waveguide with the erbium ytterbium co-doped SU-8 as the core layer was fabricated and well optical transmission ability was obtained.
Keywords/Search Tags:Erbium Ytterbium co-doped, Polymer, EDWA, Solution-Processable Complex, Nanoparticles
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