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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) - Tunable and Dual Wavelength Alexandrite Laser using the Crystal Birefringence
摘要： Red-diode-pumped Alexandrite lasers has proven to be an efficient method of generating light in the near infrared with broad tunability from 714 to 818 nm recently demonstrated [1]. Conventionally, tunable Alexandrite lasers have used wavelength selective elements such as birefringent filters or external gratings [1, 2]. In this work wavelength tuning is obtained by exploiting the birefringence of the crystal to use the crystal itself as the wavelength selective element, greatly simplifying the cavity and reducing innecessary loss components.
关键词： Alexandrite laser,red-diode-pumped,dual wavelength,tunable laser,birefringence
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) - Dual-Wavelength Chirped-Pulse Regenerative Amplifier Based on Yb:LuAP Crystal
摘要： Dual-wavelength amplifiers are in demand for a number of applications, such as laser spectroscopy, optical coherence tomography, THz generation and LIDAR instrumentation. One of the possible solution is to construct such systems based on the spectral splitting of the seed pulses generated in a laser and subsequent amplification both spectral components in an amplifier with broadband gain [1]. This leads to a significant complication of the scheme of the seed laser and amplifier. In this paper we propose a simple way to obtain dual-wavelength ultrashort pulses by using widespread femtosecond seed laser (with a spectrum without any features), fibre stretcher for spectral broadening and temporal stretching of the seed-pulses, regenerative amplifier based on Yb:LuAP crystal and grating compressor. Yb:LuAP crystal has wide and structured gain bands. Previously we demonstrated spectral broadening of the amplified pulses in the regenerative amplifier based on Yb:LuAP crystal for E//c polarization [2]. In this work we use E//b polarization for regenerative amplification of broadband pulses. The polarization is characterized by the presence of two narrow peaks in the spectrum of stimulated emission cross sections at wavelengths of about 1020 and 1040 nm. This allows us to use the active medium gain spectrum as an amplitude filter and to form two peak’s spectrum of amplified radiation, thus providing a dual-wavelength operation by using seed laser and regenerative amplifier cavities without any special spectral selectors. A conceptual scheme of the system consists of Yb:KYW seed laser (100fs, 10nJ), fibre-based stretcher, regenerative amplifier and compressor. A 10m-long single mode ?9/125 μm telecom fibre was used for pulse spectral broadening and temporal stretching (tpulse≈7.5ps). The RA setup chosen for this experiment is quite common, employing a 40-mm-long double-BaB2O4 Pockels cell for pulse injection and ejection. Pulse repetition frequency (PRF) was chosen to be 200kHz to prevent damage of the optical elements. “Off-axes” pump layout was used for longitudinal pumping of the active element [3, 4]. Main advantage of such a pump scheme is that all the cavity mirrors have highly reflecting coating at 900–1100 nm. Maximum pump power was 24 W. 2mm-long a-cut Yb(2at.%):LuAlO3 crystal was used as a gain medium. The last unit of the amplifier system is compressor based on transmission diffraction grating with 1000 grooves per millimetre. Seed, amplified pulse spectra and correspondent stimulated emission cross-section spectrum (for Yb:LuAP, E//b polarization) are shown in Fig.1. The maximum uncompressed average output power of 5.4W was obtained for E//b- polarized light after 112 RT of the pulse through the amplifier cavity, while the pulse spectral width (FWHM) was 2.9nm at 1018.3nm (short wavelength part) and 5.2nm at 1041.1nm (long wavelength part). When the incident pump power was 24 W, the optical-to-optical efficiency was as high as 22.5 %. Detailed temporal investigation of profile will be presented at the conference. In conclusion, a simple way to obtain dual-wavelength operation of chirped pulse regenerative amplifier by using the active medium gain spectrum as an amplitude filter for the formation two peak’s spectrum of amplified pulses demonstrated for the first time to our knowledge. Maximum output power of 5.4W of chirped pulses and optical-to-optical efficiency of 22.5% have been obtained for Yb:LuAP E//b-polarization at 200 kHz repetition rate.
关键词： regenerative amplifier,chirped-pulse,dual-wavelength,Yb:LuAP crystal
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) - Dual-Wavelength Y-Branch DBR-RW Diode Laser at 785 nm with Adjustable Spectral Distance from 0 up to 1.6 nm
摘要： For several applications compact light sources are requested providing two stabilised wavelengths with a narrow linewidth. Applications are shifted excitation Raman difference spectroscopy (SERDS) which separates the Raman lines from disturbing background signals such as ambient daylight or fluorescence or concentration measurements using absorption spectroscopy. Moreover, two slightly different wavelengths are needed for the difference frequency generation into THz radiation. Beside the narrowing and stabilization of the emission wavelength using an internal grating, heater elements above the implemented grating can be used to adjust the spectral distance to meet the demands for the above-mentioned applications. In this contribution, dual-wavelength Y-branch DBR-RW diode lasers emitting at 785 nm with on-chip implemented resistor heaters close to the DBR gratings similar to [1] will be presented. In contrast to the already presented work the heaters are controlled individually and thus the emission wavelength of each laser cavity can be tuned via temperature for each DBR grating separately. This enables the device to provide a flexible spectral distance of the two emission wavelengths in common laser operation of both cavities and fast alteration between both laser lines as recently demonstrated in [2]. The total length of the devices is 3 mm. Two 500 μm long 10th order passive DBR gratings, a 2 mm long S-bend shaped Y-branch coupler section and a 500 μm RW output section form the two laser resonators. The on-chip resistor heater elements are separately controllable as well the two S-bend shaped RW branches and the output RW section. The grating periods are chosen to generate two slightly different emission wavelengths with a spectral distance of 0.6 nm, i.e. 10 cm-1, suitable for SERDS. After a description of the device, electro-optical and spectral properties will be discussed with respect to the above- mentioned applications. In Fig. 1 the power-current characteristic for such dual-wavelength diode lasers is shown. Here the current IY in the Y-coupler was 0 mA, the current Iout in the RW output section was 35 mA and the heatsink temperature is 25°C. Lasing starts for both cavities at about 30 mA with a slope efficiency of 0.6 W/A. An optical output power of more than 200 mW was measured at an injection current of 400 mA. For an output power of 100 mW the spectral tuning with the individual heater elements is shown in Fig. 2 and Fig 3. Here, a flexible spectral range between 0 and 1.6 nm can be obtained while the emission of both branches shows single mode operation with a narrow bandwidth below 11 pm.
关键词： adjustable spectral distance,dual-wavelength,785 nm,Y-branch DBR-RW diode laser,absorption spectroscopy,THz radiation,SERDS
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) - Widely-Tunable Dual-Wavelength Tm:YLF, Tm:LuAG, and Tm:YAG Lasers
摘要： Dual-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 μm. 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.
关键词： Tm:YAG,birefringent filters,Tm:YLF,Tm:LuAG,dual-wavelength lasers
更新于2025-09-12 10:27:22
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Double-wavelength nanolaser based on strong coupling of localized and propagating surface plasmon
摘要： We theoretically demonstrate a kind of plasmon coupled cavity to achieve a nanolaser with high intensity and low threshold. The plasmon cavity is composed of the gold film substrate and gold disk array, which supports two strong coupled resonance modes (i.e. surface plasmon polariton (SPP) and localized surface plasmon (LSP)). Compared with the nanolaser with the LSP resonance structure, the scattering cross-section of the LSP-SPP coupled laser is 80 times higher. The coupled cavity nanolaser with different wavelengths can be excited with different plasmon resonance modes by selecting the appropriate gain medium. In addition, a compact tunable dual-wavelength laser can be developed using this coupled structure.
关键词： localized surface plasmon,nanolaser,surface plasmon polariton,dual-wavelength laser,plasmon coupled cavity
更新于2025-09-12 10:27:22
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Commentary on Combination of Sclerotherapy and Dual-Wavelength Laser in the Management of Infantile Hemangiomas in Chinese Patients
摘要： We commend the authors for their open-label clinical trial demonstrating the benefit of combination of lauromacrogol sclerotherapy and dual-wavelength vascular laser in separate visits for the treatment of infantile hemangiomas (IHs). Although oral and topical beta-blockers or oral steroids are the most commonly used treatments, some patients may be unable to tolerate or their parents unwilling to assume the systemic risks of these medications, making sclerosing agents and lasers particularly attractive, localized treatment options. Sclerosing agents may also serve as a valuable adjunct therapy to decrease the total duration of concomitant systemic therapy; enhance efficacy for large, pedunculated, or rapidly proliferating lesions that are more likely to be resistant to systemic therapies alone; or to reduce lesion bulk and reduce the risk of intraoperative bleeding before surgical excision.
关键词： infantile hemangiomas,Chinese patients,dual-wavelength laser,sclerotherapy
更新于2025-09-12 10:27:22
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Combination of Dual Wavelength Picosecond and Nanosecond Pulse Width Neodymium‐Doped Yttrium–Aluminum–Garnet Lasers for Tattoo Removal
摘要： Background and Objectives: Tattoo removal by laser has been mostly performed using Q‐switched laser, which has nanosecond pulse width. In recent years, the efficacy of treatment with picosecond pulse width laser has also been reported. Study Design/Materials and Methods: Using yttrium–aluminum–garnet laser with a potassium‐titanyl‐phosphate frequency‐doubling crystal, we performed a retrospective clinical study with combination treatment using pulse widths of 750 ps and 2 ns. The number of treatments was compared with the Kirby–Desai score. Tissue changes immediately after laser irradiation at 2 ns and 750 ps were compared using an electron microscope. Results: The combination treatment using pulse widths of 2 ns and 750 ps was safe and more effective than the Q‐switched neodymium‐doped yttrium–aluminum–garnet laser treatment. Tattoo removal was possible with significantly fewer treatment numbers than the Kirby–Desai score, without adverse events. The results from the scanning electron microscope revealed that ink particles irradiated by 750 ps were more dispersed than those by 2 ns. Conclusions: The combination treatment with pulse widths of 2 ns and 750 ps and 1064 nm and 532 nm wavelengths using the neodymium‐doped yttrium–aluminum–garnet laser was safe and effective and can be a useful option for tattoo removal.
关键词： tattoo removal,2 nanosecond,laser treatment,dual wavelength laser,750 picosecond
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) - Dual-Wavelength Dual-Comb Mode Locked Er-Doped Fiber Laser Based on Saganc Fiber Loop Mirror
摘要： We report an all-fiber dual-wavelength dual-comb mode locked fiber laser based on a Sagnac fiber loop mirror. Two asynchronous mode locked pulse trains with repetition rate difference of 218 Hz was realized.
关键词： fiber laser,Sagnac fiber loop mirror,mode locked,dual-wavelength,dual-comb
更新于2025-09-11 14:15:04
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Tunable Dual-Wavelength Self-injection Locked InGaN/GaN Green Laser Diode
摘要： We implemented a tunable dual-longitudinal-mode spacing InGaN/GaN green (521–528 nm) laser diode by employing a self-injection locking scheme that is based on an external cavity configuration and utilizing either a high or partial-reflecting mirror. A tunable longitudinal-mode spacing of 0.20 – 5.96 nm was accomplished, corresponding to a calculated frequency difference of 0.22–6.51 THz, as a result. The influence of operating current and temperature on the system performance was also investigated with a measured maximum side-mode-suppression ratio of 30.4 dB and minimum dual-mode peak optical power ratio of 0.03 dB. To shed light on the operation of the dual-wavelength device arising from the tunable longitudinal-mode spacing mechanism, the underlying physics is qualitatively described. To the best of our knowledge, this tunable longitudinal-mode-spacing dual-wavelength device is novel, and has potential applications as an alternative means in millimeter wave and THz generation, thus possibly addressing the terahertz technology gap. The dual-wavelength operation is also attractive for high-resolution imaging and broadband wireless communication.
关键词： InGaN/GaN visible lasers,Dual wavelength lasers,optical injection locking,semiconductor lasers
更新于2025-09-11 14:15:04
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Single- and dual-wavelength switchable mode-locked dissipative soliton Yb-doped fiber laser based on graphene/WS <sub/>2</sub> nanocomposites modelocker and polarization controller
摘要： We report a single- and dual-wavelength switchable mode-locked dissipative soliton in an ytterbium-doped fiber laser based on graphene/WS2 nanocomposites saturable absorber. The graphene/WS2 nanocomposites film possesses efficient saturable absorption characteristics with large modulation depth (45.1%), which results in the stable single-wavelength mode-locking operation with pulse duration of 450 ps. By carefully rotating the polarization controller, the mode-locking operation can be switched to a dual-wavelength at both 1066.4 nm and 1069.2 nm due to the modulation of the intracavity birefringence. Our work extends the studies for 2D nanomaterials and supplies potential applications in the multi-wavelength fiber laser.
关键词： mode-locked fiber laser,saturable absorber,dual-wavelength,graphene/WS2 nanocomposites,dissipative soliton
更新于2025-09-11 14:15:04