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Experimental Investigation Of Yb3+ Doped Gain Waveguide Fabrication And Waveguide Lasers

Posted on:2016-04-06Degree:MasterType:Thesis
Country:ChinaCandidate:W L TangFull Text:PDF
GTID:2308330503454637Subject:Optics
Abstract/Summary:PDF Full Text Request
Femtosecond laser writing waveguide technique is a new kind of optical waveguide technology in recent years. The production process is simple and flexible, equipment costs are low, and the true sense of the three-dimensional structure of photonic devices can be realized. This method shows a great application value in the production of high density integration micro-nano photonic chips. In this paper, we use the near-infrared femtosecond laser with repetition frequency of 50 k Hz in writing waveguides on ytterbium doped yttrium aluminum garnet crystals. By using the optical waveguide with good performance, waveguide laser experiment was successfully completed. The wavelength of the output waveguide laser was 1030 nm. There are several aspects in this paper’s main work as follows:1. Study the writing of double line waveguide in Yb3+ doped yttrium aluminum garnet crystal by using titanium sapphire laser with the pulse width of 160 fs, center wavelength of 775 nm and repetition frequency of 50 k Hz. The phenomenon of polarization guiding is discovered in the waveguide. The waveguide can guide the laser with polarization parallel to the direction of double line and the laser with polarization perpendicular to the direction of double line cannot be guided. The effect of written parameters, such as double line separation, laser pulse energy and writing speed, on the formation of the waveguide are analyzed. Experimental results show that the waveguide has good property of guiding under the writing conditions of double line separation of 30 μm, scanning speed of 400 μm/s and pulse energy of 5.0 μJ. Bivariate distribution of the waveguide refractive index is reconstructed by near-field mode and the maximum refractive index change is 1.8×10-4. A continuous waveguide laser with a wavelength of 1030.5nm is obtained and the output power is 4.7 m W.2. We report on the fabrication of embedded waveguides in single crystalline Yb:YAG by the direct femtosecond laser writing technique. Full control over the confined light spatial distribution is demonstrated by the photoinscription of high index contrast waveguides with tubular configuration. Under optical pumping with semiconductor laser radiation at 940 nm of 330 m W maximum output power, highlyefficient laser oscillation in Yb:YAG cladding waveguide at a wavelength of 1030 nm is demonstrated. The outcoupling transmissions of 91%, 50%, and 10% are investigated in the lasing experiments, respectively. The maximum output power obtained at 1030 nm is 68 m W with a slope efficiency of 35% for an outcoupling transmission of 50%. A slope efficiency as high as 44% is realized when the coupling output ratio is 91% and a low lasing threshold of 70 m W is achieved with the output coupling mirror of 10%. All of these excellent performances suggest that the femtosecond laser photoinscribed Yb:YAG crystal waveguides are promising candidates for efficient integrated laser sources.3. By using femtosecond laser with repetition frequency of 50 k Hz, center wavelength of 790 nm, and pulse width of 140 fs, double line waveguides are inscribed in Yb3+ doped phosphate glass. The influences of double-line separation, laser pulse energy and writing speed on the waveguide formation are investigated and the near-field modes of waveguides written by different laser parameters are measured, respectively. The experimental results show that the waveguide has good property of guiding under the writing conditions of double-line separation at 35 μm, pulse energy of 1.0 μJ and scanning speed of 600 μm/s. By using near-field mode, bivariate distribution of the waveguide refractive index is reconstructed with the maximum refractive index change of 1.5×10-4. The propagation loss of the waveguide is 1.56 d B/cm by testing with the scattering technique. The phenomenon of polarization guiding is discovered from the waveguide. The waveguide can guide the laser with polarization parallel to the direction of double line and the laser with polarization perpendicular to the direction of double line cannot be guided.
Keywords/Search Tags:femtosecond laser, optical waveguide, polarization transmission light, the Yb3 + doped yttrium aluminum garnet, Yb3 + doped phosphate glass, waveguide laser
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