Cr4+:YAG crystal can be used as an ultra broadband laser material and amplified spontaneous emitter, which dependents on the active ions of Cr4+. It produces broadly tunable emission in the NIR range of spectrum between 1.2 and 1.6 µm. And its relatively large absorption is located at 1.06 µm. Therefore, understanding the Cr ion oxidation states change is very important issue; then obtaining high concentration of Cr4+ and enhancing the NIR absorption are the key tasks to develop Cr4+:YAG crystal fiber, technology.
In this dissertation, the oxidation states of Cr ions in Cr:YAG crystal fibers co-doped with divalent ions have been studied quantitatively for the first time. EPMA was used to measure the concentrations of Cr and divalent co-dopant ions (Ca2+, Mg2+); which LSCM was used to acquire the concentrations of Cr and oct3+ Cr ions. tetr4+ According to the basic reactions, there are two conditions that affect the chromium valence change in the YAG crystal fiber. One is the electronic charging and recharging process, Croct4+ ↔Croct3+, which depends on temperature, the concentration of divalent ions, the ambient atmosphere, and the number of oxygen vacancies. The other is the chromium migration process, 4+ ↔ oct4+
tetr Cr
Cr , which depends on the annealing temperature. The relative stabilization energy of Cr ions between octahedral and tetrahedral sites is analyzed. The YAG fibers with Mg2+ doping showed higher relative stabilization energy than those with Ca2+. For Ca,Cr:YAG annealed in an oxygen or nitrogen environment, it was 0.25 and 0.3 eV, respectively. For Mg,Ca,Cr:YAG annealed in oxygen or nitrogen, it was 0.47 and 0.49 eV, respectively.
Oxygen annealing facilitates the + → 4+ → tatr4+ oct
3
oct Cr Cr
Cr charge compensation and
migration path. Contrarily, with nitrogen annealing treatment, the evolution of the Cr valence and migration follow a reversed path, i.e. Crtetr4+ →Croct4+ →Croctr3+ . The migration of Cr in the YAG lattice to oct4+ Cr takes place above 700 tetr4+ oC. Oxygen vacancies are the major cause of the reduced charge compensation efficiency. For the Ca,Cr:YAG sample, up to 37.3% of the divalent ions compensated the Cr3+ to Cr4+, though only 2.5% was active in fluorescence. For the Mg,Ca,Cr:YAG crystal fiber, less than 2% of the divalent ions became active for charge compensation to Cr . tetr4+
The ratio between un-reacted and total oxygen vacancies in the Ca,Cr:YAG fiber is smaller than that of the Mg,Ca,Cr:YAG fiber. The majority of the oxygen vacancies were un-reacted, which is the main reason why Cr concentrations are usually tetr4+ limited to less than 6% of the total Cr ions.
For the ASE, the Cr4+:YAG crystal fiber must have small diameter, and long length to have high efficiency. But chromium ions tend to diffuse outward during the LHPG of YAG crystal fiber, in which the average concentration of Cr4+ ion decreases significantly after each diameter-reduction step. The Cr4+ ions are replenished using an electron gun to deposit Cr2O3 and divalent-ion oxide (CaO or MgO) on the source rod circumference before growth. For the same deposition thickness, Ca,Cr:YAG has advantages over Mg,Ca,Cr:YAG crystal fiber. First of all, more Ca2+ (6× 10-4 wt.%/nm ) are diffused into YAG than Mg2+ (3×10-4 wt.%/nm). Second, the former has a lower etch-pit area per ion, i.e., 1.15×10-15 cm2/# compared with 2.89×10-15 cm2/#. The shapes and densities of the defects in divalent co-doped Cr:YAG crystal fiber strongly influence the Cr4+ fluorescence intensity. Upon the deposition of CaO and Cr2O3, the concentration was increased by 110% after re-growth and oxygen annealing at 1350 oC. Even with the out diffusion of Cr ions during growth, we achieved a Cr concentration and a ratio of tetr4+ Cr to total Cr ions of 1.76tetr4+ ×1018 cm-3 and 5.5, respectively. The Ca,Cr:YAG crystal fiber can thus be used as an ultra broadband laser material and amplified spontaneous emitter.
In the future, using electronic gun to deposit oxide material on the YAG by the LHPG method, it can adjust the dopant ions concentration in YAG. A new interesting item of research is white light based on crystal fiber. This white light from the combination of the blue, yellow, and red emissions has an apparent advantage. It has higher color-rendering index than blue/yellow white light, i.e., colors can be reproduced more vividly. Therefore, it can be more suitably used in museums, galleries, and medical applications. We try to deposit the rare-earth materials CeO2
and Sm2O3 on the circumference of pure YAG crystal fiber by electronic gun deposition system and re-growth by the LHPG method. Blue LDs were adopted for pumping source that emitted the blue light, which has a center wavelength of 449 nm.
Coupling the blue light into the core, the excitation and emission spectrum of
Ce,Sm:YAG crystal fiber can be produced, the 540-nm yellow light can be emitted by Ce ions; the 618-nm red light can be emitted by Sm ions. Combination of the yellow, blue, and red emission can produce a while light source. Presently, we are looking for proper deposition conditions to enhance the color-rendering index and luminous efficiency.
References
Chapter 1
[1.1] P. M. W. French, N. H. Rizvi, J. R. Taylor, and A. V. Shestakov,
“Continuous-wave mode-locked Cr4+:YAG laser,” Optics Letter 18, 39 (1993).
[1.2] Y. Ishida and K. Naganuma, “Compact diode-pumped all-solid-state femtosecond Cr4+:YAG laser,” Optics Letters 21, 51 (1996).
[1.3] N. Pavel, J. Saikawa, S. Kurimura, and T. Taira, “High average power diode end-pumped composite Nd:YAG laser passively Q-switched by Cr4+:YAG saturable absorber,” Japanese Journal of Applied Physics 40, 1253 (2001).
[1.4] K. Takaichi, J. Lu, T. Murai, T. Uematsu, A. Shirakawa, K. Ueda, H. Yagi, T. Yanagitani, and A. A. Kaminskii, “Chromium doped Y3Al5O12
ceramics- a novel saturable absorber for passively self-Q-switched one-micron solid state lasers,” Japanese Journal of Applied Physics 41, 96 (2002).
[1.5] H. Yagi, T. Yanagitani, H. Yoshida, M. Nakatsuka, and K. Ueda, “Highly efficient flashlamp-pumped Cr3+ and Nd3+ codoped Y3Al5O12 ceramic laser,” Japanese Journal of Applied Physics 45, 133 (2006).
[1.6] C. Y. Lo, K. Y. Huang, J. C. Chen, S. Y. Tu, and S. L. Huang, “Glass-clad Cr4+:YAG crystal fiber for the generation of superwideband amplified spontaneous emission,” Optics Letter 29, 439 (2004).
[1.7] C. Y. Lo, K. Y. Huang, J. C. Chen, C. Y. Chuang, C. C. Lai, S. L. Huang, Y. S Lin, and P. S. Yeh, “Double-clad Cr4+:YAG crystal fiber amplifier,”
Optics Letter 30, 129 (2005).
[1.8] S. Kuck, K. Petermann, U. Pohlmann, and G. Huber, “Near-infrared emission of Cr4+-doped garnets: Lifetimes, quantum efficiencies, and emission cross sections,” Physical Review B 51 (24), 17323 (1995).
[1.9] R. J. Mears, L. Reekie, I. M. Jauncey, and D. N. Payne, “Low-noise erbium-doped fiber amplifier operating at 1.54 µm,” Electronics Letters
23, 1026 (1987).
[1.10] E. Desurvire, J. R. Simpson, and P. C. Becker, “High-gain erbium-doped traveling-wave fiber amplifier,” Optics Letters 12, 888 (1987).
[1.11] J. F. Massicott, J. R. Armitage, R. Wyatt, B. J. Ainslie, and S. P.
Craig-Ryan, “High gain, broadband, 1.6 µm Er3+ doped silica fiber amplifier,” Electronics Letters 26, 1645 (1990).
[1.12] E. Ishikawa, M. Nishihara, Y. Sato, C. Ohshima, Y. Sugaya, and J.
Kumasako, “Novel 1500 nm-band EDFA with discrete Raman amplifier,”
Proceeding of European Conference on Optical Communication, 48 (2001).
[1.13] C. A. Millar and P. W. France, “Diode-laser pumped erbium-doped fluorozirconate fiber amplifier for the 1530 nm communications window,”
Electronics Letters 26, 634 (1990).
[1.14] Y. Ohishi, A. Mori, M. Yamada, H. Ono, Y. Nishida, and K. Oikawa, “Gain characteristics of tellurite-based erbium-doped fiber amplifiers for 1.5-µm broadband amplification,” Optics Letters 23, 274 (1998).
[1.15] T. Komukai, T. Yamamoto, T. Sugawa, and Y. Miyajima, “1.47 µm band Tm3+ doped fluoride fiber amplifier using a 1.064 µm upconversion pumping scheme,” Electronics Letters 29, 110 (1993).
[1.16] T. Kasamatsu, Y. Yano, and H. Sekita, “1.50-µm-band gain-shifted thulium-doped fiber amplifier with 1.05- and 1.56-µm dual-wavelength pumping,” Optics Letters 24, 1684 (1999).
[1.17] A. Cucinotta, F. Poli, and S. Selleri, “Gain characteristics of thulium-doped tellurite fiber amplifiers by dual-wavelength (800 nm+1064 nm) pumping,” Optical Fiber Communications Conference, Post Conference Digest 86, paper FB1 (2003).
[1.18] B. Cole and M. L. Dennis, “S-band amplification in a thulium doped silicate fiber,” Optical Fiber Communication Conference, Post Conference Digest 54, paper TuQ3 (2001).
[1.19] R. S. Feigelson, “Pulling optical fibers,” Journal of Crystal Growth 79, 669 (1986).
[1.20] A. Sugimoto, Y. Nobe, and K. Yamagishi, “Near-infrared laser crystals based on 3d2 ions spectroscopic studies of 3d2 ions in oxide, melilite and apatite crystals,” Journal of Crystal Growth 140, 349 (1994).
[1.21] S. Kuck, U. Pohlmann, K. Petermann, G. Huber, and T. Schonherr, “High resolution spectroscopy of Cr4+ doped Y3Al5O12,” Journal of Luminescence 60-61, 192 (1994).
[1.22] S. Fukaya, K. Adachi, M. Obara, and H. Kumagai, “The growth of Cr4+:YAG and Cr4+:GGG thin films by pulsed laser deposition,” Optics Communications 187, 373 (2001).
[1.23] S. Ishibashi, K. Naganuma, and I. Yokohama, “Cr,Ca:Y3Al5O12 laser crystal grown by the laser-heated pedestal growth method,” Journal of Crystal Growth 183, 614 (1998).
[1.24] M. M. Fejer, J. L. Nightingale, G. A. Magel, and R. L. Byer, “Laser-heated miniature pedestal growth apparatus for single-crystal optical fibers,”
Review of Scientific Instruments 55, 1791 (1984).
[1.25] A. Sugimoto, Y. Nobe, and K. Yamagishi, “Crystal growth and optical characterization of Cr,Ca:Y3Al5O12,” Journal of Crystal Growth 140, 349 (1994).
[1.26] J. C. Chen, C. Y. Lo, K. Y. Huang, F. J. Kao, S. Y. Tu, and S. L. Huang,
“Fluorescence mapping of oxidation states of Cr ions in YAG crystal fibers,” Journal of Crystal Growth 274, 522 (2005).
Chapter 2
[2.1] S. C. Abrahams and S. Geller, “Refinement of the structure of a gossularite garnet” Acta Crystallographica 11, 893 (1958).
[2.2] L. I. Krutova, N. A. Kulagin, V. A. Sandulenko, and A. V. Sandulenko,
“Electronic state and positions of chromium ions in garnet crystals” Fiz.
Tverd. Tela (Leningrad) 31, 170 (1989). [Sov. Phys. Solid State 31, 1193 (1989).]
[2.3] M. A. Gülgün, W. Y. Ching, Y. N. Xu, and M. Rühle, “Electron states of
YAG probed by energy-loss near-edge spectrometry and Ab initio calculations,” Philosophical Magazine B 79, 921 (1999).
[2.4] A. A. Kaminskii, “Laser crystals. Their physics and properties 2nd,”
Springer, New York (1990).
[2.5] C. Batchelor, W. J. Chung, S. Shen, and A. Jha, “Enhanced room-temperature emission in Cr4+ ions containing alumino-silicate glasses,” Applied Physics Letter 82, 4035 (2003).
[2.6] D. S. McClure, “Electronic spectra of molecules and ions in crystals,”
Academic Press, New York and London (1959).
[2.7] G. Boulon, “Effects of disorder on the spectral properties of Cr-doped lasses, glass ceramics and crystals,” Disordered Solids: Structure and Processes, Plenum Press, New York (1988).
[2.8] Y. Kalisky, “Cr4+-doped crystals: their use as lasers and passive Q-switches,” Progress in Quantum Electronics 28, 249 (2004).
[2.9] Y. Tanabe and S. Sugano, “On the absorption spectra of complex ions I,”
Journal of Physical Society Japan 9, 753 (1954).
[2.10] A. L. Schawlow, “Fine-line spectra of chromium ions in crystal,” Journal of Applied Physics 33, 395 (1962)
[2.11] S. Sugano, Y. Tanabe, and H. Kamimura, “Multiplets of transition-metal ions in crystals,” Academic, New York (1970).
[2.12] Y. R. Shen and K. L. Bray, “Effect of pressure and temperature on the lifetime of Cr3+ in yttrium aluminum garnet,” Physical Review B 56, 10882 (1997)
[2.13] J. C. Chen, K. Y. Huang, C. N. Tsai, Y. S. Lin, C. C. Lai, G. Y. Liu, F. J.
Kao, S. L. Huang, C. Y. Lo, Y. S. Lin, and P. Shen, “Composition dependence of the microspectroscopy of Cr ions in double-clad Cr:YAG crystal fiber,” Journal of Applied Physics 99, 093113 (2006).
[2.14] M. Grinberg, J. Barzowska, Y. R. Shen, K. L. Bray, B. V. Padlyak, and P.
P. Buchynskii, “High-pressure luminescence of Cr3+-doped CaO-Ga2O3-GeO2 glasses,” Physical Review B 65, 064203 (2002).
[2.15] J. Dong, P. Deng, and J. Xu, “Study of the effects of Cr ions on Yb in
Cr,Yb:YAG crystal,” Optics Communications 170, 255 (1999).
[2.16] J. P. Hehir, M. O. Henry, J. P. Larkin, and G. F. Imbusch, “Nature of the luminescence from YAG:Cr3+,” Journal of Physics C: Solid State Physics
7, 2241 (1974).
[2.17] B. M. Tissue, W. Jia, L. Lu, and W. M. Yen, “Coloration of chromium-doped yttrium aluminum garnet single-crystal fibers using a divalent codopant,” Journal of Applied Physics 70, 3775 (1991).
[2.18] A. Sugimoto, Y. Nobe, and K. Yamagishi, “Crystal growth and optical characterization of Cr,Ca:Y3Al5O12,” Journal of Crystal Growth 140, 349 (1994).
[2.19] S. A. Markgraf, M. F. Pangborn, and R. Dieckmann, “Influence of different divalent co-dopants on the Cr 4 + of Cr-doped Y3Al5O12 content,”
Journal of Crystal Growth 180, 81 (1997).
[2.20] Http://www.webelements.com.
[2.21] K. R. Brown and D. A. Bonnell, “Cation segregation to yttrium aluminum garnet (111) surface,” Surface Science 414, 341 (1998).
[2.22] L. Schuh, R. Metselaar, and G. de With, “Electrical transport and defect properties of Ca- and Mg-doped yttrium aluminum garnet ceramics,”
Journal of Applied Physics. 66, 2627 (1989).
[2.23] H. Eilers, U. Hommerich, S. M. Jacobsen, W. M. Yen, K. R. Hoffman, and W. Jia, “Spectroscopy and dynamics of Cr4+:Y3Al5O12
,” Physical Review
B 49 (22), 15505 (1994).[2.24] S. Kuck, K. Petermann, U. Pohlmann, and G. Huber, “Electronic and vibronic transitions of the Cr4+-doped garnets Lu3Al5O12, Y3Al5O12, Y3Ga5O12 and Gd3Ga5O12,” Journal of Luminescence 68, 1 (1996).
[2.25] R. Moncorge, D. J. Simkin, G. Cormier, and J. A. Capobianco,
“Spectroscopic properties and fluorescence dynamics in chromium-doped forsterite,” Tunable Solid State Lasers 5, 93 (1989).
[2.26] C. Deka, M. Bass, B. H. T. Chai, and Y. Shimony, “Optical spectroscopy of Cr4+:Y2SiO5,” Optical Society of America B 10, 1499 (1993).
[2.27] H. Eilers, W. M. Dennis, W. M. Yen, S. Kück, K. Peterman, G. Huber, and
W. Jia, “Performance of a Cr:YAG Laser,” IEEE Journal of Quantum Electronics 29, 2508 (1993).
[2.28] Y. Chang, “Ultrashort Optical Pulse Generation from a Cr4+-doped Yttrium Aluminium Garnet Tunable Solid-state Laser,” Ph. D. Dissertation, Université de Montréal, Quebec, Canada, (1999).
[2.29] L. I. Krutova, A. V. Lukin, V. A. Sandulenko, E. A. Sidorova, and V. M.
Solntsev, “Phototropic centers in chromium-doped garnets,” Optics and Spektrosk 63, 1174 (1987). [Optics and Spectroscopy (USSR) 63, 693 (1987).]
[2.30] S. B. Ubiszkii, S. S. Melnyk, B. V. Padlyak, A. O. Matkovskii, A.
J.-Frydel, and Z. Frukacz, “Chromium recharging processes in the Y3Al5O12: Mg, Cr single crystal under the reducing and oxidizing annealing influence,” Proceedings of SPIE 4412, 63 (2001).
[2.31] B. Henderson, H. G. Gallagher, T. P. J. Han, and M. A. Scott, “Optical spectroscopy and optimal crystal growth of some Cr4+-doped garnets,”
Journal of Physics: Condensed Matter 12, 1927 (2000).
[2.32] A. G. Okhrimchuk, and A. V. Shestakov, “Performance of YAG: Cr4+ laser crystal,” Optical Material 3, 1 (1994).
Chapter 3
[3.1] C. Y. Lo, “Growth, characterization, and application of doped-YAG single-crystal fibers,” Ph.D. dissertation, Taiwan (2004).
[3.2] J. Y. Ji, P. Shen, J. C. Chen, F. J. Kao, S. L. Huang, and C. Y. Lo, “On the deposition of Cr3−δO4 spinel particles upon laser-heated pedestal growth of Cr:YAG fiber,” Journal of Crystal Growth 282, 343 (2005).
[3.3] J. C. Chen, “Spectroscopic study on the fluorescence of Cr ions in double-clad Cr:YAG crystal fiber,” Ph.D. dissertation, Taiwan (2006).
[3.4] D. Jun, D. Peizhen, and X. Jun, “The growth of Cr4+, Yb3+:Yttrium Aluminum Garnet (YAG) crystal and its absorption spectra properties,”
Journal of Crystal Growth 203, 163 (1999).
[3.5] B. Cockayne, “Developments in melt-grown oxide crystals,” Journal of Crystal Growth 3-4, 60 (1968).
[3.6] N. I. Borodin, V. A. Zhitnyuk, A. G. Okhrimchuk, and A. V. Shestakov,
“Oscillation of an Y3Al5O12:Cr4+ laser in the wavelength region of 1.35-1.6 µm,” Bulletin of the Academy of Sciences of the USSR Physical Series 54, 54 (1990).
Chapter 4
[4.1] P. Kisliuk and W. F. Krupke, “Exchange interactions between Chromium ions in Ruby,” Journal of Applied Physics 36, 1025 (1965).
[4.2] W. C. Zheng, “Determination of the local compressibilities for Cr3+ ions in some garnet crystals from high-pressure spectroscopy,” Journal of Physics: Condensed Matter 7, 8351 (1995).
[4.3] W. Seelert and E. Strauss, “Absolute excited-state absorption cross section and fluorescence quantum efficiency of Cr3+:gadolinium scandium gallium garnet,” Optics Letters 12, 798 (1987).
[4.4] Y. R. Shen and K. L. Bray, “Effect of pressure and temperature on the lifetime of Cr3+ in yttrium aluminum garnet,” Physical Review B 56, 10882 (1997).
[4.5] M. Grinberg and J. Barzowska, “Inhomogeneous broadening of Cr3+
luminescence in doped LiTaO3
,” Physical Review B 63, 214104 (2001).
[4.6] U. Hommerich and K. L. Bray, “High-pressure laser spectroscopy of Cr3+:Gd3Sc2Ga3O12 and Cr3+:Gd3Ga5O12,” Physical Review B 51, 12133 (1995).
[4.7] B. Lipavsky, Y. Kalisky, Z. Burshtein, Y. Shimony, and S. Rotman,
“Some optical properties of Cr4+-doped crystals,” Optical Materials 13, 117 (1999).
Chapter 5
[5.1] P. Yang, P. Deng, Z. Yin, and Y. Tian, “The growth defects in Czochralski-grown Yb:YAG crystal,” Journal of Crystal Growth 218, 87 (2000).
[5.2] H. Udono and I. Kikuma, “Etch pits observation and etching properties of δ-FeSi2,” Materials Science in Semiconductor Processing 6, 413 (2003).
[5.3] A. Sennaroglu, “Analysis and optimization of lifetime thermal loading in continuous-wave Cr4+-doped solid-state lasers,” Journal of the Optical Society of America B 18, 1578 (2001).
[5.4] A. Suda, A. Kadoi, K. Nagasaka, H. Tashiro, and K. Midorikawa,
“Absorption and oscillation characteristics of a pulsed Cr4+:YAG laser investigated by a double-pulse pumping technique,” IEEE Journal of Quantum Electronics 35, 1548 (1999).
[5.5] P. C. Becker, N. A. Olsson, and J. R. Simpson, “Erbium-doped fiber amplifiers: Fundamentals and Technology,” Academic Press, San Diego, (1999).
Biography
姓名: 蔡政男 (Tsai, Cheng-Nan)
性別: 男
出生日期: 民國 51 年 4 月 1 日 出生地: 高雄市
學歷: 國立中山大學光電工程研究所 博士
私立輔仁大學物理研究所 碩士 私立中原大學物理系 學士
得獎記錄：2006 台灣光電科技研討會 (OPT) 最佳學生論文獎
博士論文題目:
中文：利用周邊蒸鍍方法提升釔鋁石榴石晶體光纖之四價摻鉻離
子濃度之研究
英文：Study of enhancement of Cr
4+concentration in Y
3Al
5O
12crystal fiber using pre-growth perimeter deposition
指導教授：國立台灣大學光電所 黃升龍 博士
Publication List
SCI listed paper:
1. C. N. Tsai, Y. S. Lin, K. Y. Huang, Y. S. Lin, C. C. Lai, and S. L. Huang
,
“
Enhancement of Cr4+ concentration in Y3Al5O12 crystal fiber with pre-growth perimeter deposition,”
To be appear inJapanese Journal of Applied physics 47 (2008).2. C. N. Tsai, K. Y. Huang, H. J. Tsai , J. C. Chen , Y. S. Lin, S. L. Huang, and Y.
S. Lin, “Distribution of oxidation states of Cr ions in Ca or Ca/Mg co-doped Cr:Y3Al5O12 single crystal fibers with nitrogen or oxygen annealing environments,” Journal of Crystal Growth 310, 2774 (2008).
3. J. C. Chen, Y. S. Lin , C. N. Tsai, K. Y. Huang , C. C. Lai, W. Z. Su, R. C. Shr, F. J. Kao, T. Y. Chang, and S. L. Huang, “400-nm-Bandwidth emission from a Cr-doped glass fiber,” IEEE Photonics Technology Letters 19, 595 (2007).
4. J. C. Chen, K. Y. Huang, C. N. Tsai, Y. S. Lin, C. C. Lai, G. Y. Liu, F. J. Kao, S.
L. Huang, C. Y. Lo, Y. S. Lin, and P. Shen, “Composition dependence of the micro-spectroscopy of Cr ions in double-clad Cr:YAG crystal fiber,” Journal of Applied Physics 99, 093113 (2006).
Conference & proceeding paper:
1. C. N. Tsai, Y. S. Lin, K. Y, Huang, C. C. Lai, S. L. Huang, “Study of the side deposition enhanced Cr4+ Concentration in Cr4+:YAG crystal fiber as an ultra broadband amplified spontaneous emitter," Conference on Lasers and Electro-Optics (CLEO) paper CTuMM6, San Jose, CA, U.S.A, 2008.
2. Y. S. Lin, C. N. Tsai, P. J. Liao, D. Y. Jheng, and S. L. Huang, “Crystal fiber based white light source using Ce,Sm:YAG as the active medium,” Conference on Lasers and Electro-Optics (CLEO), paper JThA74, San Jose, CA, U.S.A, 2008
.
3. C. N. Tsai, Y. S. Lin, K. Y. Huang, Y. S. Lin, C. C. Lai, and S. L. Huang, “The side deposition enhanced Cr4+ concentration in YAG crystal fibers,” Optics and Photonics Taiwan, paper CP-024, Tai-Chung, Taiwan, 2007
.
4. K. Y. Hsu, K. Y. Huang, C. C. Lai, Y. T. Wang, Z. W. Lin, C. N. Tsai, and S.
L. Huang, “Broadband ASE and laser based on chromium-doped double-clad crystal fibers,” Optics and Photonics Taiwan, paper C-1, Tai-Chung, Taiwan, 2007.
5. S. L. Huang, K. Y. Huang, K. Y. Hsu, C. N. Tsai, and P. S. Yeh, “Broadband emission and amplification from Chromium doped fibers,” Asia-Pacific Optical Communications (APOC), Wuhan, China, 2007
.
6. S. L. Huang, K. Y. Huang, K. Y. Hsu, and C. N. Tsai, “Broadband light source from Chromium doped fibers,” International Symposium on Next-Generation Lightwave Communications, paper T-5, Hong Kong, 2007
.
7. C. C. Lai, Y. S. Lin, C. N. Tsai, J. C. Chen, S. L. Huang, and P. Shen,
“Microstructure analysis on the YAG core of Cr4+ doped fiber amplifier,”
OptoElectronics and Communications Conference (OECC), paper 3P-002, Kaohsiung, Taiwan, Jul. 2006.
8. J. C. Chen, Y. S. Lin, C. N. Tsai, K. Y. Huang, W. Z. Su, R. C. Shr, F. J. Kao, Y.
S. Lin, and S. L. Huang, “400-nm-bandwidth emission from Cr-doped alumino-silicate fiber,” OptoElectronics and Communications Conference (OECC), paper 6D2-5, Kaohsiung, Taiwan, Jul. 2006.
9. J. C. Chen, K. Y. Huang, C. N. Tsai, Y. S. Lin, and S. L. Huang, “Broadband emission from glass-clad chromium doped Fiber,” IEEE/LEOS summer topical meeting on Fibers for Lasers, Amplifiers and Nonlinear Applications, paper WC1.2, Quebec City, Canada, Jul. 2006.
10. J. C. Chen, K. Y. Huang, C. N. Tsai, C. C. Lai, Y. S. Lin, P. Y. Chen, and S. L.
Huang, invited, “Spectroscopic characterization on the double-clad Cr4+:YAG crystal fiber amplifier,” Symposium on Optical Communications Technologies, Kaohsiung, Taiwan, Mar. 2006.
11. K. Y. Huang, C. N. Tsai, K. Y. Hsu, J. C. Chen, S. H Chen, and P. Y. Chen, Y.
S. Lin, C. C. Lai, Y. D. Huang, J. Y. Yi, Y. S. Lin, C. Y. Lo, P. Shen, T. Y.
Chang, and S. L. Huang, “Broadband optical amplifier and light source using Chromium doped fibers,” Optics and Photonics Taiwan, Hsinchu, Taiwan, 2006.
12. C. N. Tsai, K. Y. Huang, J. C. Chen, Y. S. Lin, S. L. Huang, and Y. S. Lin,
“Study of Cr oxidation states in divalent ions co-doped Cr:YAG single crystal fiber with various annealing treatments,” Optics and Photonics Taiwan, BO-40, Hsinchu, Taiwan, 2006.
13. J. C. Chen, C. N. Tsai, K. Y. Huang, Y. S. Lin, F. J. Kao, and S. L. Huang,
“Effects of side deposition and annealing for increasing Cr4+ concentration in Cr:YAG crystal fiber,” Conference on Lasers and Electro-Optics, Pacific Rim, paper CTuK4-7, Tokyo, Japan, 2005.
14. K. Y. Huang, C. C. Lai, J. C. Chen, C. N. Tsai, S. L. Huang, and Y.S. Lin,
“Nanocrystal formation in glass-clad Cr:YAG crystal fibers,” Workshop on Photonic Crystals and Nano Photonics, Taipei, Taiwan, 2005.
15. K. Y. Huang, C. Y. Lo, J. C. Chen, C. N. Tsai, C. C. Lai, S. L. Huang, and Y.
S. Lin, “Characterization on broadband chromium-doped fiber amplifier,”
Conference on Lasers and Electro-Optics (CLEO), paper CThB5, Baltimore, MD, U.S.A., 2005.
16. S. L. Huang, T. Y. Chang, P. Shen, F. J. Kao, W. H. Cheng, C. Y. Lo, Y. S.
Lin, K. Y. Huang, J. C. Chen, C. C. Lai, P. Y. Chen, C. N. Tsai, and Y. S. Lin,
“Chromium-doped wideband fiber amplifier,” Optics and Photonics Taiwan,
C-FR-V1, Tainan, Taiwan, 2005.
17. C. Y. Lo, K. Y. Huang, J. C. Chen, C. N. Tsai, C. C. Lai, S. L. Huang, and Y.
S. Lin, “Wideband chromium-doped fiber amplifier,” Symposium on Technologies for High-Capacity Optical Communications, FRI-2, Kaohsiung, Taiwan, 2004.
18. C. N. Tsai, Y. S. Lin, K. Y. Huang, J. C. Chen, C. Y. Lo, and S. L. Huang,
“Enhanced Cr4+ concentration in Cr:YAG crystal fiber by side deposition,”
Optics and Photonics Taiwan, C-SU-IV3-4, Chung-Li, Taiwan, 2004.