In this paper, a sub-kHz-linewidth wavelength-tunable single-frequency ring-cavity fiber laser operating in C- and L-band is demonstrated experimentally. our design, single-longitudinal mode achieved wide tuning range by narrow-band filtering device composed of Fabry-Pérot interferometer 1.6-m-long un-pumped Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped as dynamic grating. Under the control tunable filter, wavelength 76.69...

A significant broad-bandwidth near-shot-noise-limited intensity noise suppression of a single-frequency fiber laser is demonstrated based on semiconductor optical amplifier (SOA) with optoelectronic feedback. By exploiting the gain saturation effect SOA and feedback loop, maximum over 50 dB around relaxation oscillation frequencies bandwidth up to MHz are obtained. The relative -150 dB/Hz in frequency range from 0.8 kHz achieved, which approaches shot-noise limit. obtained signal-to-noise...

Based on a 1.8-cm-long heavily Tm3+-doped germanate fiber and being in-band-pumped by 1610 nm single-mode laser, high-efficiency high-power single-frequency distribute Bragg reflector (DBR) laser emitting at 1950 is demonstrated. The DBR has maximum output power of ~617 mW slope efficiency for the absorbed pump reaches to more than 42.2%. A stable single-longitudinal-mode with signal-to-noise ratio greater 63 dB realized. measured relative intensity-noise around -150 dB/Hz frequencies over...

A spectrally clean kHz-linewidth single-polarization single-frequency distributed Bragg reflector Yb-doped phosphate fiber (YPF) laser at 1120 nm (> 1100 nm) for the first time is demonstrated. By enhancing reflectivity of output grating and optimizing length YPF to implement effective ASE suppression single-longitudinal-mode long-wavelength lasing, a stable power over 62 mW achieved from 31-mm-long highly with linewidth 5.7 kHz. The signal noise ratio > 67 dB, polarization extinction 25...

A kHz-order linewidth controllable 1550 nm single-frequency fiber laser (SFFL) is demonstrated for the first time to our best knowledge. The control of realized by using a low-pass filtered white Gaussian noise (WGN) signal applied on stretcher in an optical feedback loop. Utilizing WGN signals with different amplitudes An and cutoff frequencies fc, linewidths are availably controlled wide range from 0.8 353 kHz. obtained signal-to-noise ratio (OSNR) more than 72.0 dB, relative intensity...

Linewidth suppression mechanism of the self-injection locked single-frequency fiber laser (SFFL) is investigated theoretically and experimentally. An analytical model based on semi-phenomenological approach built up to characterize optical feedback in SFFL. According theoretical prediction, linewidth tends be reduced with longer external cavity photon lifetime. Experimentally, a 200-Hz SFFL achieved 101 m long delay fiber, which agrees well simulation. The provides new perspective understand...

We report a narrow linewidth and low threshold single-frequency distributed Bragg reflector (DBR) fiber laser at 1120 nm based on short 1.5 cm long Nd-doped silica which, to the best of our knowledge, is first demonstration fiber-based with wavelength greater than 1100 nm. A stable single-longitudinal-mode operation signal-to-noise ratio 67 dB was verified by scanning Fabry-Perot interferometer. The as 10 mW. DBR has maximum output power 15 mW optical-to-optical efficiency for launched pump...

A noise-sidebands-free and ultra-low relative intensity noise (RIN) 1.5 μm single-frequency fiber laser is demonstrated for the first time to our best knowledge. Utilizing a self-injection locking framework booster optical amplifier, sidebands with amplitudes as high 20 dB are completely suppressed. The RIN remarkably reduced by more than 64 dB at relaxation oscillation peak retain below −150 dB/Hz in frequency range from 75 kHz 50 MHz, while quantum limit −152.9 dB/Hz. Furthermore,...

An ultra-narrow linewidth full C-band tunable single-frequency linear-polarization fiber laser based on self-injection locking has been demonstrated. By the use of a narrow-band Fabry-Perot interferometer, wavelength could be flexibly tuned from 1527 to 1563 nm with linewidths < 700 Hz. The frequency noise is less than 40 dB re Hz/Hz1/2 at low frequencies (< 100 Hz) and reaches -5 around 25 kHz. measured relative intensity (RIN) -130 dB/Hz regard over 3 MHz, while obtained linear...

A gain-switched single-frequency distributed Bragg reflector (DBR) Tm<inline-formula> <tex-math notation="LaTeX">$^{3+}$ </tex-math></inline-formula>-doped fiber pulsed laser operating at 1950 nm is demonstrated experimentally. The process realized by in-band pumping a DBR ultra-short linear cavity via 1610 (pump source). Driven this pump with varying modulation frequency, repetition rate of the output can be flexibly tuned from 1 to 500 kHz. As result, maximum peak power 34.2 W achieved 100...

Based on the heavily Er3+/Yb3+ co-doped phosphate glass fiber (EYPF) with a larger emission cross-section, an efficient linearly-polarized single-frequency distributed Bragg reflector laser at 1603 nm is demonstrated. By balancing cavity length against longitudinal mode spacing, stable single-longitudinal-mode more than 20 mW generated from 16-mm-long EYPF. The measured relative intensity noise of less –140 dB/Hz frequencies over 5 MHz. signal-to-noise ratio greater 62 dB and linewidth 1.9...

Quantum defect originating from the stimulated Raman scattering (SRS) effect is a heat source that induces refractive index grating and, thus, significantly decreases threshold of transverse mode instability (TMI), which main limiting factor for power scaling high-power fiber lasers. A semi-analytical model takes TMI and SRS effects into account was developed, impact content variation due to changes in injected seed length on investigated. Experimental demonstrations are presented. We proved...

Based on core- and in-band-pumped polarization-maintaining ${{\rm Tm}^{3 + }}$Tm3+-doped single-cladding fiber (PM-TSF, the core diameter is 9 µm) by a 1610 nm laser distributed Bragg reflector seed laser, linearly polarized single-frequency (LP-SFFL) at 1950 with an output power of 55.3 W linewidth 6.95 kHz demonstrated. The beam qualities ${M}_x^2$Mx2 ${ M}_y^2$My2 are measured to be 1.01 1.03, respectively. slope efficiency respect launched pump 71.0%, in comparison theoretical quantum...

Based on several centimeters long heavily Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped germanate fibers (TGFs) and in-band-pumped technique, a short-wavelength distribute Bragg reflector (DBR) single-frequency fiber laser (SFFL) emitting at <inline-formula xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7~\mu \text{m}$ </tex-math></inline-formula> is investigated experimentally. A stable...

An optimized bidirectional pumping fiber amplifier is demonstrated to achieve low-frequency intensity noise suppression and effective power enhancement simultaneously. Based on the concept analysis of gain saturation effect, influence input signal pump investigated systematically. Further combining with optimization configuration even-distribution gain, relative (RIN) 1083 nm single-frequency laser (SFFL) suppressed 9.1 dB in frequency range below 10 kHz. Additionally, boosted from 10.97 dBm...

In this study, a kilowatt-level high-efficiency narrow-linewidth all-fiber Tm3+-doped continuous-wave laser operating at 1.95 μm is demonstrated. Benefitting from an advanced boost design of two-stage main amplifier, it not only effectively manages heat dissipation resulting the high pump-induced quantum defect but also realizes controlled extraction optical gain and improves conversion efficiency. Finally, system has realized output power 1018 W, linewidth 3.8 GHz, slope efficiency 60.0%...

This work proposed a fast inverse design method for microwave and infrared (IR) bi-stealth metamaterials based on the equivalent circuit model (ECM). Using this method, we designed IR metamaterial by deploying multilayered structure of indium tin oxide (ITO) film metasurface. First, emissivity ITO was calculated in framework ECM. Then, an metasurface to implement low emission high transmission simultaneously. Based ECM square patch, whole established at band. An program built incorporating...

A theoretical analysis of the influence laser's linewidth on phase-OTDR sensing system is proposed and corresponding experiment demonstrated. The factor laser source introduced into signal expressions under nonquasi monochromatic light condition. effect can be transformed an exponential decay item signal. Even if range always smaller than coherent length source, detection SNR will decrease as increases. Phase-OTDR strain with controllable performed to verify derived result. result shows that...

A 1603 nm high optical signal-to-noise ratio (OSNR) kHz-linewidth linearly-polarized all-fiber single-frequency master-oscillator power amplifier (MOPA) is demonstrated. To suppress the amplified spontaneous emission from Yb3+/Er3+ ions with customized filters and optimize length of double cladding active fiber, an over 15 W stable single-longitudinal-mode laser achieved OSNR >70 dB. measured linewidth 4.5 kHz a polarization-extinction >23 dB are obtained at full output power. This L-band...

Based on heavily Tm-doped germanate glass fibers (TGFs), a short all-TGF MOPA laser system with uniform core parameters in each stage was demonstrated. An 11.7 W stable single-frequency at 1.95 μm an optical-to-optical conversion efficiency of 20.4% is obtained from homemade 31-cm-long double-cladding single-mode TGF. The estimated stimulated Brillouin scattering (SBS) threshold 980 and the measured relative intensity noise < -130 dB/Hz for frequencies above 2 MHz are achieved this system....

Based on hybrid wavelength pumping and tapered Yb-doped fibers (T-YDFs), a 650 W all-fiber single-frequency polarization-maintaining fiber amplifier was demonstrated experimentally at 1030 nm. Different pump power ratios in the T-YDF-based power-amplifier stage were proposed to investigate their influence transverse mode instability (TMI) effect. The highest TMI threshold obtained when ratio of 940 nm 976 1:4.4. A measured M2 factor 1.7 polarization extinction 14 dB maximum output obtained....