33 research outputs found
Widely unable dual-wavelength operation of Tm:YLF, Tm:LuAG, and Tm:YAG lasers using off-surface optic axis birefringent filters
Full text linkBEYATLI, Ersen/0000-0002-2548-6858; Demirbas, Umit/0000-0001-8420-8965In this work, we have demonstrated dual-wavelength continuous-wave laser operation in diode-end-pumped Tm:YLF, Tm:LuAG, and Tm:YAG lasers. A 3-mm-thick quartz birefringent filter with an optical axis 45 degrees to the surface plane was exploited for achieving broadly tunable two-color laser operation. By using the different orders of the filter with varying filter width and free spectral range values, dual-wavelength operation has been achieved in 11, 12, and 8 different wavelength pairs in Tm:YLF, Tm:LuAG, and Tm:YAG, respectively. Fine tuning of the rotation angle of the birefringent filter enabled control of laser power in each line. To our knowledge, this is the first report of multicolor laser operation in these gain media, and the technique used is applicable to other laser operation regimes including mode-locking. (C) 2018 Optical Society of AmericaTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115F053]Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) (115F053)
Low-cost multimode diode-pumped Tm:YAG and Tm:LuAG lasers
Full text linkWe report a continuous-wave operation of Tm:YAG and Tm:LuAG lasers pumped with a low-cost, multimode AlGaAs laser diode. First, the lifetime and the absorbance behavior of 5 mm, 6% Tm3+ -doped YAG and LuAG crystals were thoroughly investigated. A low-cost multimode 3W laser diode at 781 nm was then used as a pump source for the Tm3+ -doped laser systems. Using three different output couplers, up to 636 mW of output power was obtained from Tm:YAG laser, with a slope efficiency of 29% at 2017 nm. The maximum output power was 637 mW in the Tm:LuAG laser, with a slope efficiency of 28% at 2023 nm. The lasing performances showed a decreasing slope efficiency with an increasing level of output coupling, which leads to a high upconversion. Furthermore, using a birefringent filter in the resonators, the laser outputs were tuned from 1942 to 2086 nm in the Tm:YAG resonator and from 1931 to 2107 nm in the Tm:LuAG case
Widely-tunable dual-wavelength Tm:YLF, Tm:LuAG, and Tm:YAG lasers
No full textEPS Young Minds;Quantum Electronics and Optics Division2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2019 -- 23 June 2019 through 27 June 2019 -- -- 152846Dual-wavelength operation of lasers are attractive for many applications such as coherent terahertz wave generation, ultrahigh pulse repetition rate creation by optical beating, and laser ranging. Several methods could be employed for achieving multicolor laser operation including usage of specially coated cavity optics, employment of dual laser crystals, utilization of coupled cavities, and deployment of Fabry-Perot band-pass filters or volume Bragg gratings. Most of the time, these approaches provide multicolor laser operation at a single wavelength pair, and laser power in each line might fluctuate with experimental conditions (such as crystal temperature and pump power variations). In recent years, usage of intracavity birefringent filters (BRFs) was proposed as a flexible method for the generation of multicolor laser operation [1-4]. Advantages of BRFs in multicolor lasing include: (a) low cost, (b) simple operation, (c) one BRF plate empowering multicolor laser operation in many different wavelength pairs, (d) capability to control laser power in each line, (e) ability to use a rich number of filter parameters from a single BRF plate, (f) effectiveness in continuous-wave, gain-switched, Q-switched and cw mode-locked regimes, and (g) universal usage of the device in any laser that lies within the transmission bandwidth of the BRF plate. In our earlier work, we have employed a 3-mm thick, off-surface optic axis crystalline quartz BRF with an optic axis 45° to the surface of the plate to generate two-color cw laser operation in 11 and 10 different transition combinations in Cr:Nd:GSGG and Cr:LiSAF [3], respectively. In this study [5], we have demonstrated that the same BRF plate could also be used for multicolor laser operation of solid-state lasers around 2 ?m. Optimization of the rotation angle of the intracavity inserted BRF plate around different orders (rotation angles) facilitated two-color laser operation in 11, 12 and 8 different wavelength pairs in Tm:YLF, Tm:LuAG and Tm:YAG, respectively [5]. For most of the cases, fine tuning of the BRF rotation angle enabled adjustment of laser power in each line. Figure 1 (a) shows sample optical spectra for Tm:YLF, and Fig. 1 (b) demonstrates details of cavity dynamics for synchronous dual-wavelength operation of Tm:YLF at 1868 1991 nm pair. To our knowledge, this is the first report of multicolor laser operation in Tm:LuAG and Tm:YAG, and first results with a BRF in Tm:YLF [6]. Moreover, the demonstrated wide-tunability of two-color laser wavelengths is quite rare in literature. © 2019 IEEE
Self-Q-switched and multicolor operation of a Tm:LuAG laser
No full textIn this paper, we report self-Q-switched (SQS) and three-color operation of an all-solid-state Tm:LuAG laser for the first time to our knowledge. in the experiments, a low-cost 3 W AlGaAs laser diode was used to end-pump the Tm:LuAG crystal inside a four-mirror x cavity. in typical continuous-wave (cw) operation, as high as 754 mW output power was obtained with 49% power efficiency at 2023 nm. Three-color and SQS operations were initiated by fine tuning of the curved mirror separation within the stability range of the resonator. in the three-color regime, the Tm:LuAG laser produced two extra, i.e., 2019 and 2033 nm, wavelength oscillations in addition to on at 2023 nm. As high as 542 mW output power was observed in this regime. To the best of our knowledge, this is the first stable three-color laser operation obtained with an isotropic gain medium without having any birefringent elements in the cavity. Furthermore, the SQS operations were also observed at other curved mirror separations. in the SQS regime, the Tm:LuAG laser produced as fast as 13.3 kHz repetition rate pulses and as high as 42.5 mu J pulse energy. Analysis of power-dependent repetition rate data gave an estimated value of 2% for the round-trip saturable loss of the crystal. As far as we know, this is the first cw-pumped stable SQS 2 mu m laser that contains an ordered isotropic gain medium as well as the highest pulse energy obtained in any cw-pumped SQS laser. (C) 2020 Optical Society of AmericaTurkiye Bilimsel ve Teknolojik Arastirma KurumuTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115F053]Turkiye Bilimsel ve Teknolojik Arastirma Kurumu(115F053)
Self-Q-switched Cr:LiCAF laser
No full textWe report self-Q-switched operation of a Cr:LiCAF laser for the first time to our knowledge. Self-Q-switching (SQS) refers to the generation of a periodic train of Q-switched pulses from a laser cavity containing only the gain medium. Since SQS does not require any additional elements such as saturable absorbers or active modulators, it is far simpler and lower cost in comparison with other Q-switching methods. In the experiments, SQS operation was observed by using an x-shaped, astigmatically compensated laser cavity which contained only the Cr: LiCAF gain medium. A 140 mW, single-mode continuous wave (cw) diode at 660 nm was used as the pump source. In typical cw operation, the Cr: LiCAF laser produced output powers as high as 50 mW with about 50% slope efficiency. The laser had a diffraction-limited output and had a spectral width of about 0.5 nm near 795 nm. SQS operation could be initiated by fine tuning of the separation between the curved mirrors of the cavity and occurred at several discrete separations of the curved mirrors within the stability range of the resonator. Pulsed pumping of the pump diode, active cooling of the gain medium, and/or misalignment of the cavity end mirrors was not necessary to initiate SQS operation. In the SQS regime, the Cr: LiCAF laser produced about 5 mu s wide pulses at repetition rates between 10 and 30 kHz. The corresponding pulse energies and peak powers were as high as 3.75 mu J and 590 mW, respectively. SQS operation was further accompanied with (i) a decrease in the output power to the 30-45 mW range, (ii) an increase of the spectral bandwidth up to 10 nm (full width at half-maximum), and (iii) a switching of the laser output from pure TEM00 to a structured beam containing higher-order spatial modes. We present detailed experimental data describing the temporal, spectral, and spatial characteristics of the SQS Cr: LiCAF laser, as well as the effect of curved mirror separation on SQS. The power-dependent repetition rate data were further analyzed to estimate the effective small-signal loss coefficient of the saturable absorber action. (C) 2013 Optical Society of Americ
Efficient and low-threshold Alexandrite laser pumped by a single-mode diode
No full textWe report a low-threshold and efficient Alexandrite laser that is pumped by only one state-of-the-art single-spatial-mode diode. The pump diode provided 170 mW of output power at 635 nm. In continuous wave (cw) laser experiments, we demonstrated lasing thresholds as low as 13 mW, slope efficiencies as high as 36%, output powers up to 48 mW, and a tuning range extending from 736 nm to 823 nm. Laser slope efficiency, laser output power, fluorescence lifetime, and emission intensity were further shown to decrease monotonically with increasing temperature. Pure cw operation could be obtained under most circumstances. However, selfQ- switching (SQS) was also observed in slightly misaligned laser cavities. During SQS, stable pulses with pulsewidths in the 5-15 mu s range and pulse repetition rates in the 10-35 kHz range have been obtained. We believe that this compact and efficient Alexandrite laser system may be an attractive source for several applications. (C) 2014 Optical Society of Americ
Efficient Tm:YAG and Tm:LuAG lasers pumped by 681 nm tapered diodes
Full text linkPubMed: 31044902In this paper, we present highly efficient continuous-wave (cw) laser operation of Tm:YAG and Tm:LuAG lasers pumped by high-brightness red tapered diodes. The single-emitter tapered diode lasers (TDLs) provide up to 1 W of pump power around 680 nm. By adjusting the operation temperature of the TDL, the pump central wavelength could be matched to the strong absorption peak of Tm 3 ions in this region ( 3 H 6 ? 3 F 3 excitation). This absorption peak is around threefold stronger than the usually employed 785 nm transition ( 3 H 6 ? 3 H 4 ). In the cw laser experiments, we have achieved slope efficiencies exceeding 55% at room temperature, which is far above the Stokes limited slope efficiency (34%), indicating presence of a strong two-for-one cross-relaxation process. Pumping with high-brightness tapered diode lasers further facilitated usage of smaller pump spots (enabling quite low lasing thresholds) and generation of near-diffraction limited output beam profiles from standard z-type cavities. To the best of our knowledge, this is the first report of diode pumping of Tm-doped solid-state lasers around 680 nm as well as the first usage of TDLs as pump sources in Tm-doped laser systems. © 2019 Optical Society of America
Efficient and Robust Kerr-Lens Mode-Locking of Cr:LiSAF Lasers Using Gain-Matched Output Couplers
Full text linkWe have demonstrated robust and efficient Kerr-lens mode-locked operation of a low-cost, diode-pumped Cr:LiSAF laser using a gain-matched output coupler. Sub-30-fs pulses with 80-pJ pulse energy have been demonstrated with 80 mW of pump power
Restoration Project Of Ümmi Sinan S Tekke (dervish Lodge)-eyüp
Full text linkTez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006Bu çalışmada, uluslararası tarihi, doğal ve kültürel varlıkları koruma normları ışığında Osmanlı Devleti döneminde ve günümüzde de dinsel ve kültürel açıdan fazlaca manevi değeri bulunan Eyüp İlçesi’ndeki Ümmi Sinan Tekkesi binalarının mimari restorasyonu ve yeniden işlevlendirilmesi için gerekli olan projelendirmeye akademik bir adım atmak amaçlanmıştır. Genel hatlarıyla dokuz bölümde ele alınarak işlenen çalışmanın birinci bölümünde; çalışmanın amacı, kapsamı ve yöntemine değinilmiştir. İkinci, üçüncü ve dördüncü bölümlerde birbirleriyle bağlantılı olarak tasavvuf ve tarikat kavramları ile bunlar etrafında oluşan düşünsel ve kurumsal yapılara, tarikat yapılarının mimarisine, özel olarak ise tekkenin ait olduğu Halveti Sinani tarikatlarına, tarihi seyirleri gözetilerek teorik bilgilerle yer verilmiştir. Beşinci bölümde söz konusu Ümmi Sinan Tekkesi’nin, çevresi, tarihçesi, mimari donanımı ve bugünkü durumu, görsel malzemelerle desteklenerek anlatılmıştır. Altıncı bölümde restorasyonu lüzumlu kılan yapıdaki bozulmalar ve değişiklik yaratan müdahaleler gösterilmiştir. Yedinci bölümde yapılar, özgün halleri tespit edilerek restitüsyona tabi tutulmuşlardır. Sekizinci bölümde bu restitüsyondan faydalanarak yapıların yeniden işlevlendirilmeleri ve restorasyonları önerilmiştir. Dokuzuncu bölümde varılan bu restorasyon kararının uygulanması konusunda teknik ve bilimsel olarak nelere dikkat edilmesi gerektiği tavsiye niteliğinde sunulmuş, ayrıca çalışmayı yürütenin Türkiye’deki genel retorasyon anlayışına dair görüşleri dile getirilmiştir. Sonuç olarak yapıların özgün kullanımı olan tarikat yapısı işlevi yerine, ana yapı gruplarından tevhidhane ile haremin bir kısmının, halihazırda tasavvufun yaşatılması için faaliyette olan bir derneğe ‘dernek evi’ olarak, haremin kalan kısımlarının bir konut, selamlık binasının ise başka bir konut olarak kullanılmasına karar verilmiş ve önerilmiştir. Bu bağlamda yapıların hem bu işlevlerine zemin oluşturacak müdahaleler ile özellikle ahşap malzemenin korunması için gerekli olan teknik ve bilimsel koruma ve yenileme müdahaleleri ortaya konmuştur.In this study, gathering information for the restoration of Ümmi Sinan’s Tekke (dervish lodge), located in Eyüp, one of the districts having a high moral importance today and also in Ottoman period, and preparing the restoration project within the perspective of international historical and cultural preservation norms, were aimed in order to take an academic step for its restoration and re-use. In general, it was studied in nine chapters. In first chapter were explained the goal, the containing and the method of the study. In second, third and fourth, the Sufism, the Sufi-orders, their conceptions, their ideational and physical associations, the architecture of the Sufi-orders buildings in general with the tekke architecture in special in a relationship each other and Halveti Sinani Orders were mentioned theoretically in their historic development. In fifth chapter, the history, the environment, the architecture and the equipments of Ümmi Sinan’s Tekke (dervish lodge), the subject of this study, also today, was mentioned and explained through supporting of technical data and visual materials. In sixth chapter were indicated physical destructions, damages or changing’s, which cause the restoration of the ‘Tekke’. In seventh, according to the survey of their original was made the restitution of the buildings. Within the perspective of this restitution were proposed the restoration and re-use of the buildings in eighth chapter. In ninth chapter, it were suggested the important criterion while realization of this restoration and also informed the critical opinion of the study author about the restoration case in Turkey. As a result, it were decided and suggested the re-use as two houses of the ‘selamlık’(by men used part), great part of the ‘harem’ (by women used part) and small part of ‘harem’ within ‘tevhidhane’ (ritual hall of tekke) as ‘association residence’ for an actual association interested with Sufism. Keeping in mind, interferences related with new functions and conservation of the buildings, materials especially wooden materials were discussed in technical and scientific discipline.Yüksek LisansM.Sc
