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990 nm High-power High-beam-quality DFB Laser With Narrow Linewidth Controlled By Gain-coupled Effect
摘要： High-power single-longitudinal-mode regrowth-free gain-coupled distributed feedback laser diode based on ridge waveguide with periodic current injection is achieved at 990 nm. Our device is fabricated only by standard i-line lithography with micron-scale precision, obtains an excellent performance at high injection current. A continuous-wave power of over 0.681 W is achieved at 3 A. The maximum continuous-wave power at single-longitudinal-mode operation is up to 0.303 W at 1.4 A. Narrow linewidth emission has been reached with a 3 dB spectrum width less than 1.41 pm. The high side mode suppression ratio is over 35 dB. The lateral far field divergence angle is only 15.05 °, the beam quality factor M 2 is 1.245, achieving a laterally near-diffraction-limit emission. It is more beneficial for single mode fiber coupling as pumping sources and other applications which require high beam quality at high power with easy fabrication technique.
关键词： narrow linewidth,Single-longitudinal mode,Gain-coupled DFB,Semiconductor lasers
更新于2025-11-28 14:24:03
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Narrow linewidth DBR laser based on high order Bragg grating defined by i-line lithography
摘要： In order to obtain narrow linewidth semiconductor laser around 1564 nm, we design a distributed Bragg reflector (DBR) laser with high-order Bragg gratings (HOBGs) using butterfly encapsulation. The DBR laser is fabricated only by i-line lithography technology with grating period of 4.84 μm, groove width of 1.5 μm and grating length of 72 μm on a strip width of 4 μm. The 1mm-long devices achieved an output power of 9.9 mW and a side mode suppression ratio (SMSR) more than 30 dB without facet coating at an injection current of 80 mA. The lasers showed ultra-narrow Lorentz linewidth of 70 KHz. This paper provides a simple method for large-scale production of narrow linewidth semiconductor lasers.
关键词： narrow linewidth spectrum,Semiconductor laser,high-order grating,distributed Bragg reflector laser
更新于2025-11-28 14:23:57
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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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Demonstration of linewidth measurement based on phase noise analysis for a single frequency fiber laser in the 2 <i>μ</i> m band
摘要： Linewidth measurement based on phase noise analysis using a 3 × 3 coupler has been applied in the 1550 nm band. One of the obvious advantages of this method compared with the common delayed self-heterodyne method is the low loss caused by the short delay line used. Taking full advantage of this particular characteristic, the linewidth of the single frequency (SF) fiber laser in the 2 μm band can also be measured. However, a specifically experimental demonstration of this method in the 2 μm band is absent to date. In this paper, a high-performance SF thulium-doped fiber laser (TDFL) was proposed and employed for the demonstration. The TDFL operates at the center wavelength of 1942.03 nm with high stability. By means of the phase noise analysis-based linewidth measurement system with a fiber delay line of only 50 m, the linewidth of the proposed TDFL is successfully measured. When the measuring time is 0.001 s, the linewidth is ~47 kHz. Furthermore, the noise characteristics of the SF laser were simultaneously studied by this method.
关键词： 2 μm band,phase noise,single frequency fiber laser,linewidth measurement
更新于2025-11-28 14:23:57
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INVESTIGATION OF FREQUENCY NOISE AND SPECTRUM LINEWIDTH IN SEMICONDUCTOR OPTICAL AMPLIFIER
摘要： The characteristics of FM noise and linewidth of semiconductor optical amplifier without facet mirrors were theoretically analyzed and experimentally confirmed. The concept of discrete longitudinal mode for the spontaneous emission was introduced as the basis of quantum mechanical characteristics, allowing the quantitative examination of noise sources. The continuously broaden output spectrum profile of the amplified spontaneous emission (ASE) was well explained as a spectrum broadening of each longitudinal mode. We found that the linewidth of the inputted signal light hardly changes by the optical amplification in the SOA. The FM noise increases proportional to square value of the noise frequency and less affected by the electron density fluctuation, the linewidth enhancement factor and the ASE. The higher FM noise in the higher noise frequency is caused by the intrinsic phase fluctuation on the optical emission. The characteristics of the linewidth and the noise frequency dependency were experimentally confirmed.
关键词： noise,frequency noise,Optical fiber communication,linewidth,semiconductor optical amplifier
更新于2025-09-23 15:22:29
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Interplay of Bit Rate, Linewidth, Bandwidth, and Reach on Optical DMT and PAM with IMDD
摘要： We theoretically compare the performance of optical discrete multi-tone (DMT) and pulse amplitude modulation (PAM) using intensity modulated, direct detection (IMDD). PAM is a lower cost, lower complexity solution than DMT, however it is more vulnerable to chromatic dispersion on the C band. We compare DMT and PAM taking into consideration the interplay of laser linewidth, fiber length, transmission rate, and channel bandwidth. We use a semi-analytical model to examine bit error rates. We study how system parameters shift the performance advantages between DMT and PAM. Our model can also be used to find the best hardware solution and frequency band for a target modulation format and bit error rate.
关键词： PAM,O-band,C-band,chromatic dispersion,DMT,bandwidth,laser linewidth
更新于2025-09-23 15:22:29
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Evaluation of nitric oxide laser-induced fluorescence thermometry techniques in a hypersonic boundary layer
摘要： Nitric oxide planar laser-induced fluorescence was performed to measure the wall-normal distribution of static temperature through a hypersonic boundary layer. A 10-degree half-angle wedge model was oriented at a 5-degree angle of attack in the NASA Langley 31-in Mach 10 facility, resulting in a 5-degree flow turning angle and an edge Mach number of 7.6. Nitric oxide was seeded through a spanwise slot into the boundary layer upstream of the imaging region and was excited with a pulsed ultraviolet planar laser sheet. The laser was spectrally scanned across six fluorescence transitions in the (0, 0) band of the A2Σ+–X2Π system. Eighteen thermometry methods were assessed through comparison to predictions of the temperature field from computational fluid dynamics simulations. The effect of spectral resolution and laser linewidth on measurement uncertainty was also investigated. The most accurate technique was spectral peak thermometry, which achieved an accuracy of ± 31.6 K (12.6% error relative to CFD temperature). The spectral peak thermometry technique required a minimum spectral resolution between 0.074 and 0.102 cm?1 to extract meaningful temperature information from the spectra and a maximum laser linewidth of 0.49 cm?1.
关键词： Laser linewidth,Thermometry,Spectral resolution,Planar laser-induced fluorescence,Hypersonic boundary layer,Nitric oxide
更新于2025-09-23 15:21:01
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Recent progress on narrow-linewidth crystalline bulk Raman lasers
摘要： Narrow-linewidth, solid-state Raman lasers are of signi?cant importance for numerous applications. In last decade, variety of methods have been utilized to suppress the spectral linewidth of Raman laser output. In this review we summarize the recent works of narrow-linewidth and/or single-frequency solid-state Raman lasers. The mechanisms and results are addressed while the positive and negative aspects of each technique are also discussed to give the readers a reference to choose a proper narrow-linewidth method for certain applications.
关键词： F-P etalon,Injection seeding,Narrow-linewidth laser,Single-frequency laser,Raman laser,Spatial hole burning
更新于2025-09-23 15:21:01
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A simple extended-cavity diode laser using a precision mirror mount
摘要： We have developed an extended-cavity diode laser (ECDL) with a simple design by using a commercial precision mirror mount with minor modifications. Our design allows tuning of the external cavity configuration by tweaking the volume holographic grating without troublesome changes in the beam path of the laser output. The mode-hop-free tuning range of the presented ECDL is about 8 GHz with a linewidth of 475 kHz.
关键词： volume holographic grating,mode-hop-free tuning range,linewidth,extended-cavity diode laser,precision mirror mount
更新于2025-09-23 15:21:01
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High-peak-power and narrow-linewidth Q-switched Ho:YAG laser in-band pumped at 1931 nm
摘要： We describe a high-peak-power, narrow-linewidth Q-switched Ho:YAG laser at 2097 nm wing-pumped by a high power and high brightness Tm:fiber source at 1931.5 nm. The laser was wavelength locked and spectrum narrowed utilizing a volume Bragg grating as the input coupler, resulting a linewidth (FWHM) of less than 0.1 nm. At 22.7 W of incident pump power, stable pulses of 5.5 mJ pulse energy and 17.5 ns of pulse duration have been generated at repetition frequency of 1 kHz, corresponding to peak power of 314.3 kW.
关键词： narrow-linewidth,Q-switched Ho:YAG laser,volume Bragg grating,1931.5 nm,high-peak-power
更新于2025-09-23 15:21:01