With the escalating demands for optical communication network system, the need for broadband gain medium in optical communication has increased. Among them, Cr4+:YAG crystal has shown an exceptionally successful broadband amplified spontaneous emission (ASE) light source that fully cover 1.2-1.6 £gm range (3-dB bandwidth up to 265 nm). More recently, we demonstrated the realization of a waveguiding, low-loss, and ultralow threshold Cr4+:YAG double-clad crystal fiber (DCF) based ultrabroadband ASE light source, optical amplifier, and laser grown by the codrawing laser-heated pedestal growth (LHPG) technique. These results demonstrate the potential of the Cr4+:YAG DCF for the replacement of the erbium doped fiber in future optical communications. In this thesis, we focus on the correlation between the nanospectroscopy and nanostructure of the Cr:YAG DCF in order to further improve its device performance.
For nanospectroscopic and nanostructural characterizations, near-field scanning optical microscopy (NSOM) and high-resolution transmission electron microscopy (HRTEM) techniques have played key roles. In this thesis, we successfully prepared the HRTEM specimen of Cr:YAG DCF, which is heterostructure, ultrahard, but fragile. Here we show the first study on the nanospectroscopy and nanostructure of the nanocrystals in the inner cladding of Cr:YAG DCF by highly spatial resolved NSOM. The NSOM results were compared with those obtained by HRTEM. In addition, the difference in thermal expansion coefficients between a YAG core and an inner cladding creates a significant localized strain field beneath the core, which can result in optical confinement and provide the possibility to simultaneously control the Cr3+ and Cr4+ fluorescence with systematically varied growth parameters. This new class of strain-tunable Cr:YAG DCF opens up new opportunity to improve the performance of the Cr:YAG DCF based ultrabroadband light source, optical amplifier, and crystal fiber laser in all-optic fiber communications.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0723109-020248 |
| Date | 23 July 2009 |
| Creators | Wang, Shih-chang |
| Contributors | Jui-Yun Yi, Cheng-Nan Tsai, Sheng-Lung Huang, Wood-hi Cheng, Yen-Sheng Lin |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0723109-020248 |
| Rights | not_available, Copyright information available at source archive |
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