Download or read book High Power Continuous Wave Nd KGW Laser with Low Quantum Defect Diode Pumping written by Rubel Chandra Talukder and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High power diode-pumped solid state (DPSS) lasers are a rapidly growing technology that is attractive for various applications in scientific and industrial fields. DPSS lasers are highly efficient, reliable and durable with superior beam quality when compared to flash-lamp pumped solid state lasers. Double-tungstate crystal of neodymium-doped potassium gadolinium tungstate (Nd:KGW) is one of the most effective active media used in DPSS lasers for generation of continuous wave radiation and ultrashort (i.e. picosecond, 10-12 s) pulses. Unfortunately, the thermal conductivity of KGW host crystals is relatively low (~3 Wm-1K-1). This low thermal conductivity and large quantum defect while pumping with ~808 nm lead to significant thermo-optical distortions. One way to minimize thermo-optical distortions is to reduce the quantum defect. This can be done by pumping at longer wavelengths as compared to conventional 808 nm. In this work we demonstrate what we believe is the first continuous wave Nd:KGW laser with hot band diode pumping at ~910 nm. This pumping wavelength reduced the quantum defect by >46% as compared to the conventional ~808 nm pumping and resulted in significantly lower thermal lensing. The laser produced 2.9 W of average output power at 1067 nm in a diffraction limited beam for an absorbed pump power of 8.3 W. The slope efficiency and optical-to-optical efficiency were found to be 43% and 35%, respectively. Significant reduction of quantum defect offered by this pumping wavelength and availability of suitable high power laser diodes opens an attractive way to further power and efficiency scaling of the Nd:KGW lasers.

Download or read book Passively Mode locked Picosecond Nd KGW Laser with Low Quantum Defect Diode Pumping written by Md. Zubaer Eibna Halim and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid-state lasers are capable of providing versatile output characteristics with greater flexibility compared to other popular laser systems. Lasing action has been achieved in many hundreds of solid-state media, but Nd-ion doped gain media are widely used to reach high power levels with short pulses. In this work, commercially available Nd:KGW crystal served as a gain medium to achieve pulsed operation at 1067 nm. This laser crystal offers large stimulated emission crosssection and gain bandwidth which facilitates generation of high peak power pulses in the picosecond regime. The KGW crystal is monoclinic and biaxial in structure, and anisotropic in its optical and thermal properties. Due to poor thermal conductivity, this crystal can be operated within a limited power range before crystal fracture takes place. To reduce the amount of heat deposited in the gain media, we introduced a new pumping wavelength of 910 nm which reduces the quantum defect by more than 45%. Continuous-wave laser operation was optimized to operate in mode-locked regime. In order to achieve short light pulses from the continuous-wave laser, one of the end mirrors was replaced by a semiconductor saturable absorber mirror (SESAM) to generate 2.4 ps pulses at a repetition rate of 83.8 MHz. An average output power of 87 mW was obtained at lasing wavelength of 1067 nm and the beam was nearly diffraction limited with M^2 1.18. The peak power of the generated pulses was 427 W and energy of each pulse was 1 nJ. Pumping the crystal at longer wavelength (910 nm) reduced the thermal lensing of the crystal by half when compared to conventional pumping at shorter wavelength (808 nm). To the best of our knowledge, this is the first time passive mode-locking of a Nd:KGW laser was explored using the pump wavelength at 910 nm.

Download or read book Efficient CW Nd YLF Laser In band Diode pumped at 908 Nm and Its Thermal Lensing written by Zohreh Sedaghati and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Controllable Continuous wave Dual wavelength Operation of In band Diode pumped Nd GdVO4 Nd YVO4 Composite Laser written by Chinedu Onyenekwu and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Highly Efficient Diode pumped Lasers Based on In band Pumping of Nd YVO4 Crystal written by Tanant Waritanant and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Optimization of Broad area GaAs Diode Lasers for High Powers and High Efficiencies in the Temperature Range 200 220 K written by Frevert Carlo and published by . This book was released on 2019-07-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on the development of AlGaAs-based diode laser (DL) bars optimized for reaching highest powers and efficiencies at low operation temperatures. Specifically, the quasi continuous wave (QCW) pumping of cryogenically cooled Yb: YAG solid-state lasers is targeted, setting requirements on the wavelength (940 nm), the pulse conditions (pulse length 1.2 ms) and frequency (10 Hz) as well as the lowest DL operating temperature THS 200 K, consistent with economic cooling. High fill-factor bars for QCW operation are to reach high optical performance with optical output powers of P 1.5 kW and power conversion efficiencies of ŋE 60% at these power levels. Understanding the efficiency-limiting factors and the behavior at lower temperatures is necessary to design these devices. Optimizations are performed iteratively in three stages. First, vertical epitaxial designs are studied theoretically, adjusted to the targeted operation temperatures and specific laser parameters are extracted. Secondly, resulting vertical designs are processed into low power single emitters and their electro-optical behavior at low currents is experimentally assessed over a wide range of temperatures. The obtained laser parameters characteristic to the vertical design are then used to extrapolate the laser's performance up to the high targeted currents. Finally, vertical designs promising to reach the targeted values for power and efficiency are processed into high power single emitters and bars which are measured up to the highest currents. Eventually, laser bars are fabricated reaching output powers of 2 kW and efficiencies of 61% at 1.5 kW at an operation temperature of 203 K.

Download or read book High Power CW Diode Laser Array Pumped Solid State Lasers and Efficient Nonlinear Optical Frequency written by and published by . This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the interim period of this bridging contract, we have continued to work on the development of high-power cw diode-laser-array-pumped solid-state lasers. Towards that end, we have built lower power lasers in order to test individual components needed for the high-power laser, specifically we have built a 1 watt ring laser and a 5 watt slab laser. The 1 watt laser was used to study the injection locking process while assembling all the necessary electronics. We have demonstrated that it is possible to injection lock a diode- pumped laser using a single piezo-mounted mirror due to the lower intrinsic laser noise compared to an arc-lamp-pumped system. This allows us to optimize the injection locking servo loop and build a more stable locking system. The 5 watt laser was used as a test bed to find a practical way to mount the slab laser while minimizing the losses that occur at the total internal reflection (TIR) points in the slab. After trying many different means of protecting the TIR surfaces, we found that a new product from DuPont, Teflon AF 1600, has all the properties needed to provide a low loss protective coating. Using this material, the laser had a cavity loss of below 2%, which allowed for efficient operation of the laser in a side-pumped design. This laser produced 5 watts of output power with a slope efficiency near 20%.

Download or read book High Peak Power Ultra short Pulse Diode pumped Yb KGW Lasers written by Reza Akbari and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, the development of a simple, compact and cost-effective laser source which is capable of generating powerful pulses is of importance for a variety of optical applications. The commercially available Yb:KGW laser crystal is a good candidate for high power regime due to its high thermal conductivity and for ultrashort pulse generation because of its broad gain bandwidth. First, the generation of watt-level sub-100 fs pulse generation was realized by using a quantum-dot semiconductor saturable absorber mirror (QD-SESAM) in a dual-action with the Kerr lensing effect. The high power laser was one of the highest among sub-100 fs diode-pumped bulk Yb-doped lasers. The laser also delivered the shortest pulses from monoclinic double tungstate crystals and also the most powerful in the sub-60 fs regime. Next, a watt-level pure Kerr-lens mode-locked (KLM) laser was realized for the first time with Yb:KGW laser crystal pumped by a multimode fibre-coupled laser diode.

Download or read book High Power Operation of the In band Diode pumped Nd GdVO4 Lasers written by Mohammad Nadimi and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book High Power CW Diode Laser Array Pumped Solid State Lasers and Efficient Nonlinear Optical Frequency Conversion written by and published by . This book was released on 1993 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past three years we have made substantial progress toward the goal of a fiber coupled, diode laser pumped 1OOW cw Nd:YAG minislab laser. We have diode pumped a 1W ring cavity laser and have operated it in a single frequency. We have diode pumped a testbed minislab Nd:YAG laser using fiber coupled diode laser bars and generated 5W of cw, TEMoo mode output power. We have designed and are implementing a 5OW cw minislab Nd:YAG laser to be pumped by 25 diode laser bars coupled through optical fibers. We plan, in the second phase of this program, to achieve the 1OOW cw output power level in a minislab Nd:YAG laser approach proposed as the goal of this research program In addition, we have demonstrated single frequency control of a high power Nd:YAG laser oscillator by injection locking; have frequency stabilized Nd:YAG oscillators by locking to high finesse Fabry Perot resonators; have absolutely stabilized Nd:YAG to one part in 10 to the -13th power by locking to iodine; have frequency converted Nd:YAG by second harmonic generation to 11.2W of cw TEMoo mode green output; have demonstrated the first cw 2 microns OPO in lithium niobate; and have demonstrated the first cw singly resonant OPO with 2W of output in a single frequency in KTP.

Download or read book High Average Power Diode Pumped Solid State Lasers Power Scaling With High Spectral and Spatial Coherence written by and published by . This book was released on 2009 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main program objective was the development of a kilowatt class, cw Nd:YAG diode-laser-pumped solid-state laser (DPSSL) with quantum noise limited amplitude and phase, 24by7 operation capability and the ability to be repaired while in operation. The approach was a master-oscillator power-amplifier (MOPA) laser utilizing a series of zig-zag slab power amplifiers stages. We developed fiber amplifiers at the 200W level to generate power with high optical efficiency that can effectively extract energy from the power amplifier slabs. We also worked on the generation of high average power visible light by developing nonlinear optical materials with large apertures, low photo-refraction and minimal visible induced infrared absorption. The second objective was to develop a 1 joule, pulse-modulated, diffraction limited MOPA laser with less than 1 MHz line-width. A follow-on objective was frequency conversion to 1.5 or 2.0 microns for remote sensing applications. We demonstrated Yb:YAG slab lasers pumped with high brightness laser diodes. Supporting this project was the development of laser diodes operating in the 1.5 micron region for pumping of erbium doped laser hosts, and the synthesis of new low-loss polycrystalline laser host materials for in-band pumping into the upper laser level to improve the laser efficiency at eye-safe wavelengths. We developed orientation patterned Ga-As to frequency convert high peak power 1-micron radiation to eye-safe wavelengths in the mid-infrared for defense applications. The third objective, power scaling and determining the potential for phase-locking of ultra-fast laser systems for a wide range of sensing and machining applications, was demonstrated as well.

Download or read book High Power CW Diode Laser Array Pumped Solid State Lasers and Efficient Non Linear Optical Frequency Conversion written by and published by . This book was released on 1997 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this program were: development of high-power, cw diode-laser-array-pumped, Nd:YAG lasers, and efficient nonlinear frequency conversion of their output. Two minislab laser heads constructed as a single high power dual-head oscillator (96W, multi-mode) were operated separately to support Q-switched and cw nonlinear frequency conversion studies and single-frequency injection-locking studies and the start of cw amplifier research. A cw singly resonant optical parametric oscillator (SRO) utilizing bulk periodically poled LiNbO3 (PPLN) for tunable mid-IR radiation using the Q-switched laser as the pump was developed, and SHG output at 532 nm was increased from 800 mW average power (15 KHz rep rate) to 1300 mW average power (8.4 KHz rep rate). Coherent laser radar with high-power, high-coherence sources was pursued through a highly-coherent master oscillator cw power amplifier approach. We operated one laser head as a (1OW TEM00) oscillator and the second laser head as a triple-pass amplifier achieving 26 W TEM00 output. More extensive experiments on cw diode-laser pumped laser amplifiers for high-power, high-coherence sources were carried out to test the ability of theoretical modeling to predict amplifier output power.

Download or read book High Power Scalable Diode laser pumped CW Nd YAG Laser Using a Stable unstable Resonator written by Damien Mudge and published by . This book was released on 2000 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reports on the development of a scalable high power laser for gravitational wave interferometry.

Download or read book Diode Pumping of Average power Solid State Lasers written by Georg F. Albrecht and published by SPIE-International Society for Optical Engineering. This book was released on 1993 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Passive Q switching of a Diode pumped Neodymium YAG Laser written by Jeffrey Allen Morris and published by . This book was released on 1991 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling of Performance of Diode Pumped Nd written by Ehsan Alimohammadian and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Power Diode Lasers written by Reinhart Poprawe and published by . This book was released on 2007-03-12 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book summarizes the work and the results of a five year government funded research project as well as subsequent research results about high power diode laser systems and their application in the field of materials processing. The entire technology chain, starting from the semiconductor technology, over cooling mounting and assembly, beam shaping and system technology down to the applications in processing of several kinds of materials (metals, polymers) are treated in the book. Theoretical models, a wide field of important parameters and practical hints and tips are provided. The book is the most extensive work on high power diode laser systems and materials processing applications.