- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Theoretical Analysis and Design of Longitudinal Leaky SAW Device Consisting of ScA1N Film / Piezoelectric Single Crystal Substrate
摘要： Theoretical Analysis and Design of Longitudinally Pumped Erbium-Doped Fiber Amplifiers for High-Power Operation
关键词： Fiber optics,Optical amplification,Erbium-doped fiber amplifier,Longitudinal pumping,High-power operation
更新于2025-09-19 17:15:36
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Thin-Disk Laser Emitting Beams with 980 W of CW-Output Power and Radial Polarization
摘要： Within the past decade, a variety of scientific groups have demonstrated the potential of radially and azimuthally polarized laser beams in many applications [1-3]. Experimental investigations in high-power operation indicate additional beneficial properties for material processing, such as drilling and deep-penetration-welding, which have been demonstrated to lead to an increase of the process efficiency by using such a polarization state. Cutting of metal sheets with radially polarized beams at 1 micron wavelength have been reported recently to increase the process efficiency [4]. In the present work, we report on the generation of radially polarized laser beams in cw operation by using grating-waveguide mirror (GWM) [5]. The grating design is based on the leaky-mode coupling mechanism, which allows for sufficient reduction of the reflectivity of the polarization state (azimuthal or radial) to be suppressed in the resonator. It consists of a circular sub-wavelength diffraction grating integrated into a highly or partially reflective dielectric multilayer mirror. At the central wavelength of the Yb:LuAG TDL, i.e., at 1030 nm, the absolute values of the reflectivities for the TE- and TM-polarized light were measured to be (55.2 ± 0.2)% and (99.8 ± 0.2)%, respectively. This corresponds to a reflectivity difference of approximately 45%. At wavelengths of 1023, 1042, and 1059 nm, the reflectivity of the TE-polarized beam was measured to be <1%, making the grating attractive for other applications with lasers operating within this wavelength range. The grating was implemented as cavity end mirror in an Yb:LuAG thin-disk laser setup, pumped at its “zero-phonon” line, i.e. λ = 969 nm. The implementation of the GWM led to the extraction of a radially polarized beam with an output power of 980 W and an optical efficiency of 50.5%. Single transversal mode operation of a radially polarized LG01 mode was sustained for the whole output power range with beam quality factors of Mx2 = 2.0 and My2 = 2.3. Figure 1(a) shows a photograph of the GWM. In Fig. 1(b), the performance of the laser and the far field intensity distribution of the emitted laser beam is shown. A qualitative analysis of the polarization was carried out by recording the intensity distributions transmitted through a rotating polarizer at different orientations of its transmission axis. Furthermore, the purity of polarization (degree of polarization) was measured with a custom-made camera-based 2D Stokes-polarimeter. An average degree of radial polarization of 95% was measured.
关键词： grating-waveguide mirror,high-power operation,radially polarized laser beams,material processing,Yb:LuAG thin-disk laser
更新于2025-09-12 10:27:22
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Monolithic Master Oscillator with Tapered Power Amplifier Diode Laser at 1060 nm with Additional Control Section for High Power Operation
摘要： State of the art diode laser light sources for high power operation with good beam quality are distributed Bragg reflector tapered diode lasers (DBR-TPLs). These devices deliver over 10 W of spectrally narrowband emission within an almost diffraction-limited beam [1]. However, due to the integration of the tapered section into the resonator, these devices are designed that only a forward traveling wave is optimal confined and amplified. This trade-off limits the potential of these devices. One way to overcome this limitation is to move the tapered section outside of the resonator and use as a single pass power amplifier in a monolithic master oscillator power amplifier (MOPA) layout [2]–[4]. However, the benefits on the emissions characteristics, as discussed below, of these devices can diminish if multi-cavity operation occurs. In this work, we present results on recently developed monolithic MOPAs for enhanced suppression of multi-cavity operation. The MOs in these devices are 2 mm long with a 7th order DBR grating at the front- and backside and a 0.75 mm long active section in the middle. An active 0.5 mm long control section (CON) follows the MO section. Both have a ridge waveguide (RW) width of 5 μm. The PA section is 3.5 mm long and defined by the tapered p-side contact with a full angle of 6°. The 3 different layouts are depicted in Fig. 1 a). In the first layout (top) all three section are in a straight line perpendicular to the front facet. The second layout (middle) has a MO section tilted by 4° and a bent CON section and the third layout (bottom) has bent CON section and a PA section tilted by 4°. Fig. 1 a) Sketch of all three monolithic MOPA layouts. b) Optical output power (solid lines) and the peak wavelength (dots) for three different monolithic MOPAs. The straight layout is used as reference to discuss the benefits of a bent control section and either a tilted MO or tilted PA on the emission characteristics of the devices. Furthermore the influence of the control section on the emission characteristics of the devices will be presented. This includes a comparison of the optical output power, the spectra and the beam quality factor of the devices. All devices provide over 6 W of optical output power at 1060 nm within a narrow spectral bandwidth below 17 pm (spectrometer resolution limit). However the overall emission characteristics have clear differences as can be seen in Fig. 1 b). Here the optical output power and the peak wavelength are plotted in dependence of the PA current. The laser with the tilted MO layout shows a small increase in output power compared to the straight layout and a reduction of spectral mode jumps for PA currents below IPA = 8 A. For the laser with the tilted PA layout the small spectral mode jumps due to multi-cavity operation are completely suppressed but the output power is reduced by 0.5 W.
关键词： MOPA,spectral bandwidth,diode laser,monolithic master oscillator power amplifier,high power operation,beam quality
更新于2025-09-11 14:15:04