Diode-pumped Continuous Wave Hybrid Nd:phosphate Glass and Nd:YVO4 Laser PDF Download

Author: Sukanya Tachatraiphop
Publisher:
ISBN:
Category :
Languages : en
Pages : 122

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Author: Clifford R. Pollock
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 540

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Author: Marek Osiński
Publisher: SPIE-International Society for Optical Engineering
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 906

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This work brings together a series of papers dealing with various aspects of advanced high-power laser technology.

Author: Sukanya Tachatraiphop
Publisher:
ISBN:
Category : Mode-locked lasers
Languages : en
Pages : 324

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Author:
Publisher:
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Category : Electrical engineering
Languages : en
Pages : 2240

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Author: Ehsan Alimohammadian
Publisher:
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Category :
Languages : en
Pages :

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Author: Chinedu Onyenekwu
Publisher:
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Category :
Languages : en
Pages : 0

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This thesis presents a controllable continuous-wave dual-wavelength diode-pumped laser based on a composite Nd:GdVO4/Nd:YVO4 crystal. Controllability for the pair of spectral output was achieved by changing the operating temperature of the fiber-coupled laser diode pump using a digital temperature controller. The resulting temperature-dictated pumping wavelength provided a precise and turnkey means of intensity control for the two emitted spectral lines as either line showed strong and proportionate intensity change in response to the wavelength of excitation by the pump. The intensity ratio for the pair was in favor of the GdVO4 emission at 1063 nm while pumping at about 912 nm while the YVO4 emission was relatively lower and vice versa while pumping at 914 nm. For power scalability, a low-quantum defect (QD) approach was adopted using in-band pumping. This was specifically performed around the 910 - 914 nm wavelength range considering and corresponding to the longer Nd:GdVO4/Nd:YVO4 absorption bands. Using this efficiency-increasing initiative, the laser produced a maximum output power of 4.48 W with 11.55 W of absorbed power, corresponding to a slope and optical-to-optical efficiency of 43.8 % and 38.8 % respectively. These parameters are notably the highest ever reported compared to all previous works using a similar composite crystal for dual wavelength operation.

Author: Mohammad Nadimi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The main obstacle in power scaling of the well-known Nd-doped lasers such as Nd:YVO4 is the thermal lensing effect. One of the proposed solutions to effectively alleviate this problem was based on the reduction of heating within the laser crystal. This was extensively investigated with the Nd:YVO4 crystal by pumping the laser at 914 nm instead of the standard pumping at 808 nm wavelength. In context of high power applications, the crystal of Nd:GdVO4 is an interesting alternative to the Nd:YVO4 as it offers the benefits of good spectral features (similar to Nd:YVO4) and much higher thermal conductivity. However, there is only one proof-of-principle work on continuous-wave (CW) Nd:GdVO4 laser using this pumping approach in which an output power of 3.35 W was reported. The full power scaling potential of the Nd:GdVO4 laser crystal to produce high output power has not been demonstrated to date. In this PhD thesis, I addressed this issue and investigated the high power operation of Nd:GdVO4 lasers under a new pumping wavelength of 912 nm. First, the thermal lensing behaviour of a 1063 nm Nd:GdVO4 was studied, both experimentally and by finite element analysis (FEA) method. The thermal lensing strength in Nd:GdVO4 laser under 912 nm pumping was significantly reduced when compared to the Nd:GdVO4 laser with 808 nm pumping or even Nd:YVO4 laser with 914 nm pumping. The next step of this research was focused on high power operation of Nd:GdVO4 lasers where we achieved 19.8 W of output power at 1063 nm. As a side work in the CW regime of operation, the possibility of discrete wavelength tuning and dual-wavelength operation of the Nd:GdVO4 laser were examined by using an intracavity birefringent filter. Discrete wavelength operation at four different wavelengths was demonstrated. Furthermore, for the first time we were able to demonstrate a dual-wavelength operation of the Nd:GdVO4 laser as a 1063 and 1071 nm wavelength pair. The last aspect of this PhD thesis was concentrated on generation of picosecond pulses. We were able to report on the first semiconductor saturable absorber mirror (SESAM) mode-locked (ML) Nd:GdVO4 laser with 912 nm pumping. The laser generated 10.14 W of average output power with the pulse width of 16 ps at the repetition rate of 85.2 MHz. To the best of our knowledge this is the highest average output power ever obtained from any of the SESAM mode-locked Nd-doped solid-state lasers that were pumped around 912 nm.

Author: Zohreh Sedaghati
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Diode-pumped solid-state lasers are highly recommended for a variety of industrial and scientific applications as they can offer high efficiency and excellent beam quality. However, power scaling of these lasers is a challenging task. The main limitation in power scaling of famous neodymium doped lasers such as Nd:YVO4 is the thermal lensing effect. Thermal lensing degrades the output beam quality and in extreme cases can result in crystal fracture. One potential solution to this problem is to reduce the induced heat load inside the gain media by decreasing the quantum defect. This was demonstrated successfully for the Nd:YVO4 laser by pumping the laser at a long wavelength of 914 nm instead of the traditional pumping at 808 nm wavelength. Among the Nd-doped crystals operating in the near infrared range, the crystal of yttrium lithium fluoride (Nd:YLF) is another interesting gain medium as it has the benefits of natural birefringence (can generate naturally polarized laser beam), negative dn/dT (reduces thermal effects) and long upper level lifetime (in favor of Q-switched operation). In this work we used a long wavelength pumping approach and for the first time examined the performance of a continuous-wave Nd:YLF laser at 1047 nm under 908 nm diode pumping. This pumping wavelength reduced the quantum defect by 50% as compared to the conventional 808 nm pumping. The laser produced an output power of 850 mW at 1047 nm with excellent beam quality and 625 mW at 1053 nm. The slope efficiency was ~73.9% and 46% for 1047 and 1053 nm, respectively. Therefore, a considerable power scaling is possible for Nd:YLF crystals owing to the strongly reduced quantum defect and, hence, thermal lensing.

Author: Tanant Waritanant
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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This work proposed to study Neodymium-doped laser crystals as an alternative for ultrashort pulse generation with medium output power level and high efficiency. The first section of this thesis focused on the thermal effect which is the main limitation in power scaling. The results showed that the thermal lensing effect is significantly reduced with in-band pumping at 914 nm. Aside from thermal lens effect investigation, discrete wavelength tuning and dual-wavelength operations were demonstrated with intracavity birefringent plates. Mode locking operations with SESAM as saturable absorber was demonstrated under 914 nm pump wavelength for the first time with the highest efficiency to date. The output in mode-locked regime was stable and self-starting with 16 ps pulse duration which can be extended to adjacent emission lines at 1073 nm and 1085 nm. Finally, two important candidates for low quantum defect pumping, Nd:CALYO and Nd:SYSO, were identified and tested for the first time.