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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Characterization of a MOPA system used for underwater optical communication
摘要： Underwater optical communication (UWOC) requires high-power laser transmitter with good beam quality for high-rate data modulation. Since master oscillator power amplifier (MOPA) has the characteristic of preserving the property of seed laser (e.g. bandwidth and beam quality), it is expected to resolve the problem. In this paper, we theoretically simulate the large-signal modeling of the amplified laser light and the frequency response of a MOPA system and experimentally amplified 3-mW 1-um light to 145mW. The seed light came from 1064-nm TO-Packaged laser diode and was coupled into HI1060. To satisfy the requirements of the transmitters for UWOC, we used second harmonic generation and got 0.06mW 532-nm laser light. Finally, according to the theoretical analysis of a MOPA system and the electrical response of a laser driver, we chose Manchester Encoding to modulate the amplified 1064-nm laser light and achieved 100-Mbps transmission. The system was error free for 1?104 bits.
关键词： MOPA,UWOC,SHG
更新于2025-09-16 10:30:52
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[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) - Widely Tunable Watt-Level MOPA Systems Emitting at 976 nm
摘要： Tunable diode laser sources are key components in absorption spectroscopy, biomedical imaging and in optical telecommunication systems, to mention a few examples. The term tunable refers here to laser sources with a mechanism for precise control of the emission wavelength, while maintaining a narrow spectral linewidth. In addition, multiple applications require high output power with good beam quality. In this work, we present results on recently developed light sources that fulfil these different requirements. These are based on a hybrid master oscillator power amplifier (MOPA) concept, which utilizes a tunable MO combined with a tapered power amplifier (TPA). The MO serves as the wavelength selective element, while the PA ensures amplification to the Watt-level from a nearly diffraction limited beam. These miniaturized systems are constructed on micro benches, on top of 25 mm × 25 mm laser mounts.
关键词： high output power,wavelength tuning,tunable diode laser,MOPA,beam quality
更新于2025-09-12 10:27:22
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[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) - Rare-Earth Doped Phosphate Optical Fibres and Rods for Compact Pulsed Optical Amplification
摘要： In the last decade high energy and high peak power pulsed laser sources have been in a great demand for a variety of applications such as remote sensing (LIDAR, DIAL), range findings, communications systems and material processing. Since the energy of the pulsed laser oscillator is generally much lower than the one required for the applications, a fibre amplifier is commonly used to boost the output power, realizing the so called MOPA (Master Oscillator Power Amplifier) laser architecture. The realization of a fibre amplifier requires an active medium with high optical gain in short length, in order to mitigate nonlinear optical effects. Multicomponent phosphate glasses are recognized to be an ideal host material for the realization of these fibres, as they can be doped with large amounts of rare earth (RE) ions (up to 1021 ions/cm3) without clustering, thus allowing the fabrication of extremely compact active devices with high optical gain (> 5 dB/cm) in short length [1,2]. Moreover, phosphate glasses possess good thermo-mechanical properties, high emission cross-sections, high optical damage threshold and are less susceptible than silica to photodarkening [3,4]. With the aim of realizing short-length amplifiers in the 1 μm and 1.5 μm wavelength range, highly Yb3+ and Yb3+-Er3+-doped custom phosphate glass compositions were designed and fabricated by melt-quenching technique. Suitable cladding compositions were explored. The manufactured glasses were thoroughly investigated. First of all, they were thermo-mechanically characterized, then the glasses underwent optical characterization such as refractive index measurement, FTIR spectroscopy and, for active glass, RE emission spectroscopy resolved in time and frequency. Phosphate fibers and rods were then manufactured by preform drawing using a custom induction heated optical fiber drawing tower, with the preform being obtained by rod-in-tube technique. Preliminary results of optical amplification are presented for a single stage MOPA, both in the 1 μm and 1.5 μm wavelength range.
关键词： compact pulsed optical amplification,Yb3+-Er3+-doped,MOPA,phosphate glass compositions,Yb3+,rare-earth doped phosphate optical fibres
更新于2025-09-11 14:15:04
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[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) - All-Fiber 100-ns Single-Frequency 0.5mJ Anisotropic MOPA with Double Clad Tapered Yb-Doped Gain Fiber
摘要： High peak power, single-frequency pulsed fiber MOPA sources with extremely narrow line and nanosecond pulses are in highly demand to date. Such sources are required for various applications, including coherent LIDARs systems, remote sensing, and frequency conversion [1]. Stimulated Brillouin scattering (SBS) arising is a main obstacle to further peak power and pulse energy scaling [2]. There are several strategies for SBS suppression in the fiber MOPA have been described in the literature to date. These include exploiting a longitudinal temperature or mechanical stresses gradient in a gain fiber [3] or by using a birefringent fiber with both eigenstates excited. In [4] Stolen has demonstrated doubling of SBS threshold in birefringent fiber with equally excited fast and slow waves. Tapering of a fiber is significantly increases a SBS threshold [5].Usually, authors have used only one of abovementioned strategies for SBS mitigation. Meanwhile, all these measures might be imposed simultaneously by using a short, active, tapered, end pumped (aiming strong temperature gradient) fiber with large mode field diameter fiber. The experimental set up is shown in Fig.1. In conclusion, we have presented short (1.2m), tapered, birefringent, ytterbium doped, end pumped double clad fiber MOPA system with 40μm mode field diameter for amplification of single-frequency long pulses (100ns) for coherent LIDAR application. We have reached record 0.522mJ pulse energy and demonstrated highest to date 5kW peak power by using anisotropic active tapered double clad fiber as a gain media and exciting both slow and fast polarization waves.
关键词： single-frequency,tapered fiber,SBS suppression,fiber MOPA,coherent LIDAR
更新于2025-09-11 14:15:04
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[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) - High Energy Pulsed Operation of a Yb Fibre MOPA with Amplified Spontaneous Emission Output
摘要： High energy pulsed fibre lasers are attractive to numerous applications in areas including industry, science, metrology and defense due to their excellent characteristics such as high average powers, a diffraction-limited beam quality, compactness and high flexibility in operation. However, their pulse energy is often limited by nonlinear optical phenomena, such as SBS (Stimulated Brillouin Scattering), SRS (Stimulated Raman scattering), self-focusing, etc., due to the small core size, resulting in unstable operation and catastrophic damage of the fibre. Enlarging the core size along with shortening the fibre length is a simple and straightforward way to overcome this problem, but at the expense of beam quality degradation and increased thermal effects. Fibre-based superfluorescent sources (FSS), sometimes referred to as amplified-spontaneous-emission (ASE) fibre light sources, can be an alternative way to achieve higher pulse energy from a typical step-index fibre while preserving the good beam characteristics of the fibre laser. Since the FSS has a broad spectrum without longitudinal modes, its spectral power is smaller than that of the fibre laser, increasing SBS threshold and, hence, generation of a high energy pulse. In this study, we report pulsed operation of the fibre-based superfluorescent light source. From a Yb fibre MOPA using an ASE source as a seed, we successfully generated high energy superfluorescent light pulses and investigated its performance for different repetition rates, pulse widths, and spectral linewidths. Furthermore, the results were compared with those of a Yb fibre laser.
关键词： ASE fibre light sources,self-focusing,fibre-based superfluorescent sources,nonlinear optical phenomena,amplified spontaneous emission,SBS,SRS,Yb fibre MOPA,High energy pulsed fibre lasers
更新于2025-09-11 14:15:04
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[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