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High-power, high-spectral-purity GaSb-based laterally coupled distributed feedback lasers with metal gratings emitting at 2? <i> <b>μ</b> </i> m
摘要： We report on the fabrication of high-power, high-spectral-purity GaSb-based laterally coupled distributed feedback (LC-DFB) lasers emitting at 2 μm. Second-order Chromium-Bragg-gratings are fabricated alongside the ridge waveguide by lift off. Due to the introduction of gain coupling, the lasers exhibit a stable single mode operation [side-mode suppression ratio (SMSR) >40 dB] from 10 °C to 50 °C and the maximum SMSR is as high as 53 dB. At a heat-sink temperature of 10 °C, the lasers emit more than 40 mW continuous-wave in a single longitudinal mode. A high external quantum efficiency of 48% is obtained, resulting in a notable increase in power conversion efficiency peaking at 13%. The lasers achieve a comparable output power with that of the index-coupled LC-DFB lasers, while maintaining a better single mode performance. Thus, we prove the feasibility of the metal-grating LC-DFB structure to achieve high-power, frequency-stable semiconductor lasers through a simpler and much more convenient way.
关键词： metal gratings,high-spectral-purity,high-power,distributed feedback lasers,GaSb-based lasers
更新于2025-11-28 14:24:03
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High-power single-longitudinal-mode double-tapered gain-coupled distributed feedback semiconductor lasers based on periodic anodes defined by i-line lithography
摘要： In this paper, we demonstrate a regrowth-free double-tapered gain-coupled distributed feedback semiconductor laser. It is designed based on periodic surface current injection to reach a high-power and single-longitudinal mode. A continuous-wave output power of over 1.2 W/facet is achieved at 4 A. High single-longitudinal-mode output power reaches up to 0.9 W/facet at 3 A at each uncoated facet. The side mode suppression ratio is nearly 30 dB at 980 nm. The 3 dB spectral width is less than 2.7 pm. The lateral far field divergence angle is only 14.5 °, the beam quality factor M2 is 1.7, achieving a near-diffraction-limit emission. Our device, produced by standard i-line lithography, enhances the output power while obtaining the pleasurable spectral and spatial properties. It has great potential in widespread commercial applications such as high efficiency pumping sources for its low-cost, easy fabrication technique and excellent performance.
关键词： Double-tapered,Distributed feedback lasers,Gain-coupled,Semiconductor lasers
更新于2025-11-28 14:24:03
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Narrow-line InGaN/GaN green laser diode with high-order distributed-feedback surface grating
摘要： We demonstrate narrow-line green laser emission at 513.85 nm with a linewidth of 31 pm and side-mode suppression ratio of 36.9 dB, operating under continuous-wave injection at room temperature. A high-order (40th) distributed-feedback surface grating fabricated on multimode InGaN-based green laser diodes via a focused ion beam produces resolution-limited, single-mode lasing with an optical power of 14 mW, lasing threshold of 7.27 kA cm?2, and maximum slope efficiency of 0.32 W A?1. Our realization of narrow-line green laser diodes opens a pathway toward efficient optical communications, sensing, and atomic clocks.
关键词： InGaN/GaN,green laser diode,distributed-feedback,narrow-line,surface grating
更新于2025-11-28 14:23:57
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Narrow-Strip 670 nm Gain-Coupled Distributed Feedback Laser Based on Periodic Anodes Fabricated by I-Line Lithography
摘要： A narrow-strip single-longitudinal-mode gain-coupled distributed feedback semi-conductor laser with a central wavelength of approximately 670 nm is demonstrated. We fabricate a novel micro-scale regrowth-free gain-coupled grating with an island-like shape without nanoscale gratings by i-line lithography only. The maximum output power from the ?ber of the device with butter?y package is 48.1 mW at 100 mA and its slope ef?ciency is 0.79 W/A. The laser can be continuously tuned from 670.750 to 670.784 nm with a side-mode suppression ratio of over 40 dB, covering the absorptive peak of lithium atoms. Our easily fabricated devices have great potential as light sources in many applications such as lithium atom detectors.
关键词： continuous tunability,gain-coupled,distributed-feedback,Semiconductor laser
更新于2025-11-28 14:23:57
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2nd-order random lasing in a multimode diode-pumped graded-index fiber
摘要： Raman lasing in a graded-index fiber (GIF) attracts now great deal of attention due to the opportunity to convert high-power multimode laser diode radiation into the Stokes wave with beam quality improvement based on the Raman clean-up effect. Here we report on the cascaded Raman generation of the 2nd Stokes order in the 1.1-km long GIF with 100-μm core directly pumped by 915-nm diodes. In the studied all-fiber scheme, the 1st Stokes order is generated at 950–954 nm in a linear cavity formed at GIF ends by two fiber Bragg gratings (FBGs) securing beam quality improvement from M2 ≈ 30 to M2 ≈ 2.3 due to special transverse structure of FBGs. The 2nd Stokes wave is generated either in linear (two FBGs) or half-open (one FBG) cavity with random distributed feedback via Rayleigh backscattering. Their comparison shows that the random lasing provides better beam quality and higher slope efficiency. Nearly diffraction limited beam (M2 ≈ 1.6) with power up to 27 W at maximum gain (996 nm), and 17 W at the detuned wavelength of 978 nm has been obtained, thus demonstrating that the 2nd-order random lasing in diode-pumped GIF with FBGs provides high-efficiency high-quality beam generation in a broad wavelength range within the Raman gain spectral profile.
关键词： laser diode,fiber Bragg gratings,beam quality,graded-index fiber,Raman lasing,random distributed feedback
更新于2025-09-23 15:21:21
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Microwave behavior of a monolithic dual-wavelength DFB laser based on current injection model
摘要： A driving current based model describing the optical heterodyne output of a monolithic dual-wavelength DFB laser is established. The linear relationship between the driving current and the laser output wavelength was applied to obtain the simple equation for this purpose. Actual measured data from the real devices were used for the initial parameter extraction and the practical model can then be built. By using this model, the influence of different laser parameters towards the radio frequency signal generation and different current configuration on the output characteristic can be demonstrated. This can facilitate the future design of such integrated photonic devices.
关键词： Dual-wavelength,Distributed feedback (DFB) laser,Monolithic
更新于2025-09-23 15:21:01
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Random distributed feedback fiber lasers: Impact of third-order dispersion
摘要： In this paper, one of the most modern random lasers known as random distributed feedback ˉber laser is investigated when the third-order dispersion (TOD) is taken into account. The laser characteristics are simulated based on the nonlinear Schr€odinger equations (NLSEs) where the power evolution of three interacting waves: the pump, the forward and the backward Stokes waves, are investigated as they propagate down the ˉber. The results show that due to TOD, the output characteristics of the laser are changed and particularly, the output power becomes asymmetrical. Moreover, the impacts of ˉber nonlinear coe±cient and input power on the output power and the output spectrum are studied.
关键词： nonlinear Schr€odinger equations (NLSEs),third-order dispersion,Random distributed feedback ˉber laser
更新于2025-09-23 15:21:01
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Highly efficient surface-emitting semiconductor lasers exploiting quasi-crystalline distributed feedback photonic patterns
摘要： Quasi-crystal distributed feedback lasers do not require any form of mirror cavity to amplify and extract radiation. Once implemented on the top surface of a semiconductor laser, a quasi-crystal pattern can be used to tune both the radiation feedback and the extraction of highly radiative and high-quality-factor optical modes that do not have a defined symmetric or anti-symmetric nature. Therefore, this methodology offers the possibility to achieve efficient emission, combined with tailored spectra and controlled beam divergence. Here, we apply this concept to a one-dimensional quantum cascade wire laser. By lithographically patterning a series of air slits with different widths, following the Octonacci sequence, on the top metal layer of a double-metal quantum cascade laser operating at THz frequencies, we can vary the emission from single-frequency-mode to multimode over a 530-GHz bandwidth, achieving a maximum peak optical power of 240 mW (190 mW) in multimode (single-frequency-mode) lasers, with record slope efficiencies for multimode surface-emitting disordered THz lasers up to ≈570 mW/A at 78 K and ≈720 mW/A at 20 K and wall-plug efficiencies of η ≈ 1%.
关键词： quantum cascade laser,surface-emitting,Quasi-crystal,THz frequencies,Octonacci sequence,semiconductor lasers,distributed feedback
更新于2025-09-23 15:21:01
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Multi-wavelength colloidal quantum dot lasers in distributed feedback cavities
摘要： Lasers with multi-wavelength colloidal quantum dots (CQDs) can be achieved using complex grating structures and ?exible substrate. The structure contains graduated periods and rectangular cavity fabricated through interference lithography, which acts as the distributed feedback cavity. A layer of densely packed CQD ?lm is deposited on the cavity via spin coating technique. The performance of CQD lasers based on di?erent distributed feedback cavities is investigated. Multi-wavelength lasing is achieved based on a ?exible rectangular cavity.
关键词： ?exible,tunable,distributed feedback,quantum dots lasers,multi-wavelength
更新于2025-09-23 15:21:01
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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 2.07 μm Distributed Feedback Laser Based on π-Phase-Shifted FBG Inscribed in Heavily Doped Holmium Fiber by Femtosecond Laser Pulses
摘要： Distributed-feedback (DFB) fiber laser is a versatile source of low-noise single-frequency radiation that finds applications in spectroscopy, optical communications and sensing devices. Depending on the active medium, different lasing wavelengths can be obtained: 1.03–1.12 μm for Yb, 1.53–1.62 μm for Er, and 1.73–1.93 μm for Tm-doped fibers. Special fiber Bragg grating (FBG) with a length of 20–70 mm and phase shift in the structure, directly written in an active medium, serves as distributed feedback cavity of this type of laser. Commonly, special UV photosensitive fibers and phase masks inscription technique are used for an FBG fabrication. Alternative femtosecond (fs) point-by-point technique [1] has a number of advantages as compared to UV-based ones: 1) wide variety of active fibers can serve as a host material for an FBG, thanks to the nonlinear mechanism of fs pulses absorption, 2) FBG period can be easily tuned by controlling fs pulses frequency and velocity of fiber translation during the inscription process, 3) each fiber grating “pitch” can be written independently, which means that phase shift with an exact value and position along FBG can be introduced. Despite the number of publications dealing with holmium fiber lasers [2], there no publications devoted to DFB ones. At the same time, such type of laser sources has a great potential as a master oscillator in all-fiber coherent beam combination systems [3]. We report on the creation of holmium-doped DFB fiber laser with a wavelength of 2.07 μm operating in single-frequency regime (Fig. 1a). The laser is based on custom-made single-mode holmium-doped fiber having absorption coefficient about 43 dB/m at 1.125 μm, which is the wavelength of pump Yb fiber laser. 42-mm π-phase-shifted FBG was directly inscribed in the active fiber by femtosecond IR laser pulses and served as distributed feedback cavity of the laser. Lasing threshold was reached at 350 mW pump power, and output power exceeded 36 mW at pump power of 4.8 W (Fig. 1b). Single-polarization mode operation was observed with linewidth of ~10 kHz. Additionally to the room-temperature operation regime we will present and discuss the laser operation regimes at cryogenic temperature (77 K), as well as high-temperature (>400 K). To the best of our knowledge, it is the first realization of all-fiber DFB laser based on holmium active medium.
关键词： femtosecond laser pulses,holmium-doped fiber,single-frequency radiation,Distributed-feedback fiber laser,π-phase-shifted FBG
更新于2025-09-23 15:19:57