• Title/Summary/Keyword: Laser Cladding

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High Power Continuous-Wave and Graphene Q-switched Operation of Er:YAG Ceramic Lasers at ~1.6 ㎛

  • Wang, Yong;Chen, Hao;Shen, Deyuan;Zhang, Jian;Tang, Dingyuan
    • Journal of the Optical Society of Korea
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    • v.17 no.1
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    • pp.5-9
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    • 2013
  • We report on high-power continuous-wave operations of an Er:YAG ceramic laser in-band pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. With an output coupler of 10% transmission, the ceramic laser yielded 16.7 W of continuous-wave output at 1645 nm for 28.8 W of incident pump power, corresponding to a slope efficiency of 61.0% with respect to the incident pump power. The lasing wavelength switched to 1617 nm when output couplers of > 20% transmission were used. Up to 16.2 W of 1617 nm output was generated for 33.0 W of incident pump power, corresponding to a slope efficiency of 51.8%. Graphene Q-switched operation of Er:YAG cermic laser at 1645 nm was also demonstrated with stable pulses of 30-74 kHz repetition rates and 1.5-6.4 ${\mu}s$ pulse widths.

Recent Study in Variation of Welding Materials for Overlay Welding (오버레이 용접에 있어서 용접재료에 따른 최신 연구동향)

  • Yoo, Ho-Cheon
    • Journal of Welding and Joining
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    • v.31 no.6
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    • pp.17-26
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    • 2013
  • Recent developing tendency of overlay welding on welding materials are studied by searching of NDSL, Science Direct, KIPRIS and so on. Fe, Co, Ni and WC are selected as welding materials. Development and improvement of various new overlay welding technology, especially improvement of quality and formation of crack are introduced. Also the prospective technologies of overlay welding are anticipated.

Effect of Process Parameters on Laser Overlay Behavior of Fe-based Alloy Powder on Aluminum Substrate (공정 변수에 따른 Al 모재와 Fe계 합금 분말의 레이저 오버레이층 거동)

  • Yoo, Yeon-Gon;Kang, Nam-Hyun;Kim, Cheol-Hee;Kim, Jeong-Han;Kim, Mok-Soon
    • Journal of Welding and Joining
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    • v.25 no.1
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    • pp.30-36
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    • 2007
  • A joining of dissimilar metal combination faces significant problems such as poor strength and cracking associated with brittle intermetallic compounds(IMC) formed. An application of laser allows low heat input; leading to less dilution and smaller heat affected zone. The $CO_2$ laser overlay was conducted on an AC2B alloy with feeding Fe-based powders. The overlay area was significantly influenced from the travel velocity rather than the powder feeding rate. The interface between the overlay and substrate consisted of the hard and brittle IMC($FeAl_3,\;Fe_3Al,\;Fe_2Al_5$), which initiating and propagating the crack. The reciprocating test for the slide wear was conducted on a multi-pass overlay experiment. Comparing with the multi-pass overlay with no overlap, the overlay with 50% overlap showed better wear resistance.

Fabrication of All-fiber 7x1 Pump Combiner Based on a Fiber Chip for High Power Fiber Lasers (고출력 광섬유 레이저를 위한 광섬유 칩 기반 All-fiber 7x1 펌프 광 결합기 제작)

  • Choi, In Seok;Jeon, Min Yong;Seo, Hong-Seok
    • Korean Journal of Optics and Photonics
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    • v.28 no.4
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    • pp.135-140
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    • 2017
  • In this paper, we report measured results for an all-fiber $7{\times}1$ pump combiner based on an optical fiber chip for high-power fiber lasers. An optical-fiber chip was fabricated by etching a fiber, having core and cladding diameters of 20 and $400{\mu}m$, in the longitudinal direction. To both ends of the etched chip, we spliced input and output fibers. First, we tied together seven optical fibers, having core and cladding diameters of 105 and $125{\mu}m$ respectively, in a cylindrical bundle and spliced them to the $375-{\mu}m$ end of the optical-fiber chip. Then, we attached an output DCF with core and cladding diameters of 25 and $250{\mu}m$ to the $250-{\mu}m$ end of the optical-fiber chip. Finally, the fabricated $7{\times}1$ pump combiner showed an average optical coupling efficiency of about 90.2% per port. This chip-based pump combiner may replace conventional pump combiners by massive production of fiber chips.

Deposition Characteristics and Mechanical Properties of Stainless Steel 316L Fabricated via Directed Energy Deposition (에너지 제어 용착을 이용한 스테인리스 316L의 적층 특성 및 기계적 물성 평가)

  • Yang, Seung-weon;Lee, Hyub;Shim, Do-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.6
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    • pp.59-69
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    • 2021
  • Directed energy deposition (DED) is an additive manufacturing technology involving a focused high-power laser or electron beam propagating over the substrate, resulting in melt pool formation while simultaneously supplying metal powder to the melt pool area to deposit the material. DED is performed to repair and strengthen parts in various applications, as it can be easily integrate local area cladding and cross-material deposition. In this study, we characterize stainless steel 316 L parts fabricated via DED based on various deposition conditions and geometries to widen the application of DED. The deposition characteristics are investigated by varying the laser power and powder feed rate. Multilayer deposition with a laser power of 362 W and a powder feed rate of 6.61 g/min indicate a height closest to the design value while affording high surface quality. The microhardness of the specimen increases from the top to the bottom of the deposited area. Tensile tests of specimens with two different deposition directions indicate that horizontally long specimens with respect to a substrate demonstrate a higher ultimate tensile strength and yield strength than vertically long specimens with lower elongation.

Proposal and Analysis of Characteristics of a Refractive Index Modulated Distributed Feedback Laser Diode (Refractive Index Modulated Distributed Feedback Laser Diode의 제안과 특성해석)

  • 김홍국;이홍석;김부균;김병호
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.5
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    • pp.88-98
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    • 1999
  • A refractive index modulated (RIM) DFB laser, in which the refractive index of a center region of the upper cladding layer comprising the grating region is different from that of side regions, is proposed to obtain and effective ${\lambda}$/4 phase shift in the center region. Since the coupling coefficient of a center region in a RIM-DFB laser is larger than that of side regions, a RIM-DFB laser has the effect of a distributed coupling coefficient. Simulation results show that RIM-DFB lasers have better operation characteristics - more uniform photon density profile, less SHB effect, and better single mode operation at high injection currents - compared to those of ${\lambda}$/4 phase-shifted DFB lasers and CPM-DFB lasers. In addition, the effect of the center region on the above threshold characteristics of a RIM-DFB laser is investigated.

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Near Infrared Laser Based on Polymer Waveguide Bragg Grating (폴리머 광도파로 브래그 격자 기반의 근적외선 레이저)

  • Kim, Kyung-Jo;Son, Nam-Seon;Kim, Jun-Whee;Oh, Min-Cheol
    • Korean Journal of Optics and Photonics
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    • v.22 no.4
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    • pp.179-183
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    • 2011
  • An external cavity laser operating at near infrared wavelength is demonstrated by incorporating polymer waveguide Bragg reflectors. 3rd order Bragg grating and oversized rip waveguide structure were designed by using the effective index method and the transmission matrix method. The polymer waveguide was fabricated using polymer materials with refractive indices of 1.462 and 1.435 for the core and the cladding layers, respectively. The external feedback laser with 875-nm Bragg grating exhibits single mode lasing located at 850-nm wavelength with an output power of 0 dBm, a 20-dB bandwidth of 0.2 nm and a side mode suppression ratio of 40 dB.

High-power Yb Fiber Laser with 3.0-kW Output (3.0 kW 고출력 발진 단일 모드 Yb 광섬유 레이저)

  • Park, Jong Seon;Park, Eun Ji;Oh, Ye Jin;Jeong, Hoon;Kim, Ji Won;Jung, Yeji;Lee, Kangin;Lee, Yongsoo;Cho, Joonyong
    • Korean Journal of Optics and Photonics
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    • v.32 no.4
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    • pp.147-152
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    • 2021
  • We report high-power continuous-wave operation of a Yb-doped fiber laser at 1070 nm, pumped by high-power laser diodes at 976 nm. Based on theoretical calculation of the stimulated Raman scattering and temperature distribution in the fiber, we construct a bidirectionally pumped Yb-fiberlaser system incorporating a pair of fiber Bragg gratings and a cladding light stripper. The fiber laser yields 3.0 kW of continuous-wave output at 1070 nm in a diffraction-limited beam with M2 ≈ 1.26 for 4.1 kW of incident pump power, corresponding to a slope efficiency of 81.5%. The prospects for further power scaling are discussed.

Linearly Polarized 1-kW 20/400-㎛ Yb-doped Fiber Laser with 10-GHz Linewidth (선편광된 10 GHz 선폭의 1 kW급 20/400-㎛ 이터븀 첨가 광섬유 레이저)

  • Jung, Yeji;Jung, Minwan;Lee, Kangin;Kim, Taewoo;Kim, Jae-Ihn;Lee, Yongsoo;Cho, Joonyong
    • Korean Journal of Optics and Photonics
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    • v.32 no.3
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    • pp.120-125
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    • 2021
  • We have developed a linearly polarized high-power Yb-doped fiber laser in the master oscillator power amplifier (MOPA) scheme for efficient spectral beam combining. We modulated the phase of the seed laser by pseudo-random binary sequence (PRBS), with the bit length optimized to suppress stimulated Brillouin scattering (SBS), and subsequently amplified seed power in a 3-stage amplifier system. We have constructed by coiling the polarization-maintaining (PM) Yb-doped fiber, with core and cladding diameters of 20 ㎛ and 400 ㎛ respectively, to a diameter of 9-12 cm for suppression of the mode instability (MI). Finally, we obtained an output power of 1.004 kW with a slope efficiency of 83.7% in the main amplification stage. The beam quality factor M2 and the polarization extinction ratio (PER) were measured to be 1.12 and 21.5 dB respectively. Furthermore, the peak-intensity difference between the Rayleigh signal and SBS signal was observed to be 2.36 dB in the backward spectra, indicating that SBS is successfully suppressed. In addition, it can be expected that the MI does not occur because not only there is no decrease in slope efficiency, but also the beam quality for each amplified output is maintained.