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All-polarization-maintaining dual-wavelength mode-locked fiber laser based on Sagnac loop filter
摘要： We demonstrate an all polarization-maintaining (PM) fiber based dual-wavelength mode-locked Er-fiber laser. A nonlinear amplifying loop mirror (NALM) with an intracavity nonreciprocal phase shifter is used for self-started mode-locking. A short segment of PM fiber is angle-spliced to the NALM, functioning as a PM Sagnac loop filter, thus enabling dual-wavelength mode-locking. The wavelength separation is solely determined by the angle-spliced PM fiber length. Stable dual-wavelength mode-locking operation is switchable between 1570/1581 nm and 1581/1594 nm. The two-color pulse trains oscillating in the same cavity have an inherent offset repetition rate of ~1 kHz owing to cavity dispersion, allowing future high precision dual-comb applications with a simple and robust configuration.
关键词： polarization-maintaining fiber,dual-comb applications,dual-wavelength mode-locked fiber laser,Sagnac loop filter
更新于2025-11-28 14:24:03
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Ultrafast mode-locked dual-wavelength thulium-doped fiber laser using a Mach-Zehnder interferometric filter
摘要： A simple and robust method to generate a dual-wavelength mode-locked laser using a tunable Mach-Zehnder filter (TMZF) and a single-wall carbon nanotube (SWCNT) based saturable absorber (SA) is proposed and demonstrated. The proposed laser uses a thulium-doped fiber for lasing in the two-micron region and exploits the interferometric spectrum of the TMZF to produce dual peaks with nearly equal magnitude. SWCNT based SA enables mode-locking at a threshold value of 150.4 mW with distinct dual-wavelength peaks at 1919.2 nm and 1963.7 nm. The peaks have a calculated pulse width of 1.8 ps and 1.6 ps, respectively with a repetition rate of 9.1 MHz with a relatively high optical-signal-to-noise ratio value of 59.1 dB. The output is also observed to remain unchanged over time, indicating high stability. The proposed laser has a promising application, particularly in ultrafast gas molecular spectroscopy and sensing.
关键词： Thulium-doped fiber laser,Mode-locking,Dual-wavelength,Mach-Zehnder filter
更新于2025-11-28 14:24:03
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Switchable dual-wavelength fiber laser based on a phase-shifted fiber Bragg grating combined with Mach-Zehnder interferometer and Sagnac loop
摘要： A switchable dual-wavelength erbium-doped fiber laser is proposed and demonstrated. It is based on the finer filter effect of phase-shifted fiber Bragg grating (PSFBG), combining with the compound interference filtering effect of Mach-Zehnder interferometer (MZI) and Sagnac loop. By adjusting the polarization controller (PC) and tuning the delay, the switchable single- and dual-wavelength fiber laser with tunable wavelength spacing can be obtained. As a result, the dual-wavelength spacing as small as 0.04 nm is achieved, the output wavelength is from 1555.580 nm to 1559.928 nm, and the side mode suppression ratio (SMSR) is larger than 40 dB. The maximum wavelength drift of single-wavelength is less than 0.033 nm, and the maximum fluctuation of dual-wavelength is less than 0.02 nm. The experimental results show that the proposed fiber laser has important applications, such as in high fineness dense wavelength division multiplexing (DWDM) systems and other similar fields.
关键词： Switchable dual-wavelength,Mach-Zehnder interferometer,Fiber laser,Sagnac loop,PSFBG
更新于2025-11-28 14:24:03
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Narrow no-gain competition linewidth dual-wavelength laser at 912?nm and 1064 nm
摘要： A narrow linewidth, no-gain competition, 912 nm quasi-three level and 1064 nm four-level dual-wavelength laser is presented for the first time. This system consists of an intra-cavity pumped Nd:YVO4 laser emitting at 1064 nm, using a 912 nm Nd:GdVO4 laser. A Fabry-Perot etalon is used to compress the linewidth located at the common parts of the 912 nm and 1064 nm laser resonators. When the etalon, with an angle of refraction of 15°, was introduced into the cavity, the narrow linewidth dual-wavelength laser was obtained. The corresponding minimum linewidths were 0.284 nm and 0.627 nm.
关键词： intra-cavity pumped,dual-wavelength,narrow linewidth
更新于2025-11-28 14:23:57
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Dual-wavelength thulium/holmium-doped fiber laser generation in 2 <i>μ</i> m region with high side-mode suppression ratio
摘要： We demonstrate a dual-wavelength laser with emission in the 2 μm wavelength region using a thulium/holmium co-doped fiber and a non-adiabatic tapered fiber as a comb filter. The configuration employed a backward pumping scheme and dual-wavelength laser was generated at 2023.53 and 2032.82 nm. The side-mode suppression ratio (SMSR) is more than 44 dB with overall good stability performance. The proposed configuration presents a simple yet practical scheme of generating 2 μm dual-wavelength laser with good SMSR. This investigation may offer a more efficient yet eye safe dual-wavelength related applications for end users.
关键词： comb filter,tapered fiber,side-mode suppression ratio,thulium/holmium-doped fiber laser,dual-wavelength laser
更新于2025-11-28 14:23:57
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Construction of 879?nm direct intra-cavity pumped dual-wavelength laser operating at 912?nm and 1064?nm
摘要： A dual-wavelength continuous-wave laser with direct intra-cavity pumping using a 879 nm laser diode that utilizes Nd:GdVO4 and Nd:YVO4 crystals, is presented. To the best of our knowledge, this system completely eliminates the gain competition between the 912 nm and 1064 nm transitions for the first time. A theoretical model is introduced to describe this intra-cavity pumped dual-wavelength laser. The lasing threshold of the 912 nm Nd:GdVO4 laser is presented by considering the ground-state reabsorption loss effect. A total output power of 1.33 W at dual-wavelength operation with an absorbed pump power of 7.91 W is experimentally achieved. The individual output power for the 912 nm and 1064 nm emissions were 0.43 W and 0.9 W, respectively. Both wavelengths operate in TEM00 mode with a total slope efficiency > 20%.
关键词： Lasers,Neodymium,Dual-wavelength,Solid-state,Intra-cavity pumped
更新于2025-11-28 14:23:57
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Fast and simple interrogation of extrinsic Fabry–Perot interferometer sensor based on dual-wavelength intensity ratio
摘要： A fast and simple demodulation method for the variation of Fabry-Perot (FP) cavity length is proposed and demonstrated. Taking advantages of differentially detecting optical power intensities of dual-wavelength, a reliable linear correlation between the variation of FP cavity length and differential intensity ratio of dual-wavelength can be obtained. Besides, an extrinsic Fabry-Perot interferometer (EFPI) sensor with a length of 196.8 um was used to demonstrate performance of the method, and the time for each experimental operation is within 100 ms by the demodulation method and an integrable tunable laser assembly (ITLA). The demodulation resolution of 0.726 nm was achieved for the change of cavity length in a strain sensing experiment. By selecting two wavelengths at different positions in the system, the linear ranges of FP cavity length variation are 180 nm, 150 nm, and 130 nm responding to the sensitivities of -0.01099 nm-1, -0.01485 nm-1, and -0.02253 nm-1, respectively. It shows a high flexibility between the linear range and the sensitivity. Consequently, the different requirements of the EFPI sensor system can be easily fulfilled through appropriate selections of two different wavelengths. Moreover, the advantages of simplicity, fast speed, low cost can be fully revealed in the demodulation of large-scale production EFPI sensors.
关键词： Fabry-Perot cavity,Fiber sensors,Dual-wavelength.
更新于2025-11-28 14:23:57
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[IEEE 2018 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Beijing, China (2018.7.29-2018.8.1)] 2018 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Dual-polarization ultra-thin tunable AMC surface for P/L bands applications
摘要： A dual-wavelength laser diode (DWLD) with a novel structure for optoelectronic applications is presented. The device operates at 1550 nm and 1310 nm wavelengths, achieving high output power and stable performance. Experimental results demonstrate its potential for use in optical communication systems.
关键词： 1310 nm,optical communication,1550 nm,dual-wavelength laser diode,optoelectronics
更新于2025-11-28 14:23:57
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An Improved Method for Determination of Pentosans in Pulps using Dual-Wavelength Spectroscopy
摘要： The aim of this study was to determine the pentosan content in pulps by a dual-wavelength spectrophotometric method. The method was based on the boiling reaction between pentosan and 12% hydrochloric acid, in which pentosan was subsequently converted to furfural. The concentration of furfural in the distillate was determined by the absorbance at 280 nm and 290 nm. Several different simultaneous equations were solved to obtain the concentrations of furfural in the distillate. The results showed that the method had an excellent accuracy (RSD ≤ 0.61%) and reproducibility (RSD = 3.25%). The spectral interference of the 5-hydroxymethyl-2-furaldehyde in the distillate was eliminated by the dual-wavelength measurement technique. Compared with the TAPPI method (colorimetric method), this method is simple, user-friendly, and practical and has high detection sensitivity.
关键词： Dual-wavelength spectroscopy,Furfural,HMF,Pentosans
更新于2025-09-23 15:23:52
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Handheld Retinal Oximetry in Healthy Young Adults
摘要： Purpose: The objective of this study was to measure the relative retinal oxygen saturation with a prototype, mobile handheld oximeter in upright and supine position and to compare these measurements to the gold standard Oxymap T1 retinal oximeter in upright position. A handheld oximeter is needed for measurements of infants with retinopathy of prematurity as well as acutely injured and bedridden adults. Methods: Healthy volunteers (age 18–35) were recruited at the Leiden University Medical Center. Retinal images were acquired with the handheld oximeter and the Oxymap T1. Both cameras are dual-wavelength oximeters and acquire images with wavelengths of 570 and 600 nm. Retinal oxygen saturation values were determined for both the handheld camera and the Oxymap T1. Results: Twenty-one subjects (age 25 6 2 years) were included. In upright position, the oxygen saturation for the arterioles was 92.2% to 4.9% vs. 95.5% 6 4.2% and for the venules 57.9% 6 10.2% vs. 57.7% 6 6.4% for the handheld camera and Oxymap T1, respectively. The oxygen saturation was higher in the arterioles than the venules for both cameras (P , 0.05). In supine position, measured with the handheld oximeter, the oxygen saturation in the arterioles was 92.3% 6 5.8% and 59.2% 6 6.1% in the venules. Conclusions: Performance of the prototype, mobile handheld oximeter Corimap camera compares well with the Oxymap T1, with a slightly larger standard deviation in oxygen saturation measurements, both in upright and supine patients. Translation Relevance: To date, to our knowledge, no oximeters are available for handheld use and for measurement in supine position in infants and bedridden adults. Here we tested such an oximeter and show that its performance compares well with that of the gold standard Oxymap T1 in healthy adults.
关键词： handheld oximetry,dual-wavelength oximetry,retinal oximetry
更新于2025-09-23 15:22:29