Er/Yb co-doped 345-W all-fiber laser at 1535 nm using hybrid fiber.

The 1.5-µm fiber laser is widely used in the fields of laser lidar, remote sensing, and gas monitoring because of its advantages of being eye-safe and exhibiting low atmospheric transmission loss. However, due to the ∼1-µm amplified spontaneous emission (ASE) of the Er/Yb co-doped fiber (EYDF), it is difficult to improve the laser power.

3 × 1 fiber signal combiner with high beam quality Gaussian-like beam for a 10kW-level fiber laser.

We present the design and fabrication of a 3 × 1 signal combiner with high beam quality based on supermode theory. For improving beam quality, the fiber with core diameter of 34 µm and numerical aperture of 0.11 is first chosen as the output fiber.

Low-numerical aperture confined-doped long-tapered Yb-doped silica fiber for a single-mode high-power fiber amplifier.

A low-numerical aperture (NA) confined-doped long-tapered (LCT) Yb-doped fiber is proposed and fabricated by modified chemical vapor deposition combined with solution doping technique. The LCT fiber owns the core NA of ∼0.05 and the gain dopant doping diameter ratio of ∼77%, with a core/cladding diameter of 25/400 µm at both ends and 37.

Extended L-band few-mode Er/Yb Co-doped fiber amplifier with a cladding-pumped pseudo-two-stage configuration.

Spatial division multiplexing (SDM) is one of the most important technologies that may help to solve the future capacity crisis. However, to date, SDM optical amplification is still a challenge for its application. Herein, we numerically and experimentally demonstrated a few-mode Er/Yb co-doped fiber amplifier (FM-EYDFA) for extended L-band operation.

The Changes of Amygdala Transcriptome in Autism Rat Model After Arginine Vasopressin Treatment.

Background: Some studies have shown that arginine vasopressin (AVP) can significantly improve the social interaction disorder of autism, but the mechanism remains unclear.

Methods: Female Wistar rats were intraperitoneally injected with VPA or normal saline at embryonic day 12.5 to establish an autism model or normal control in their offspring.

Extending the L-band amplification to 1623 nm using Er/Yb/P co-doped phosphosilicate fiber.

The gain bandwidth of the erbium-doped fiber amplifier limits the enhancement of the transmission capacity in optical fiber communication systems. This Letter reports an erbium-ytterbium co-doped phosphosilicate fiber, which is expected to increase transmission capacity by extending the L-band gain bandwidth to 1623 nm. The fiber was fabricated by modified chemical vapor deposition combined with solution doping technology.

Thermal bleaching of photodarkening and heat-induced loss and spectral broadening in Tm-doped fibers.

We demonstrate the thermal bleaching effect on a photodarkened thulium-doped fiber (TDF) in detail. The bleaching effect on visible transmission initiates at 250 °C and a complete recovery is achieved at 550 °C. Prior to the recovery, a post-irradiation heat-induced spectral loss is observed.

Bleaching of photodarkening in Tm-doped silica fiber with deuterium loading.

We demonstrate the rapid photodarkening (PD) phenomenon in Tm-doped fiber (TDF) core pumped by a laser at 1080 nm and the bleaching effect of deuterium (${{\rm D}_2}$D) on PD TDF. By ${{\rm D}_2}$D loading for seven days, the PD-induced excess loss (PIEL) in the visible (VIS) and near-infrared (NIR) region have been largely eliminated, and no degradation was observed within 30 days. PD resistance of the ${{\rm D}_2}$D pretreated TDF has been investigated as well.

Promotion of pulse peak power by halving the repetition rate based on a vector soliton.

We report on an all-fiber mode-locked repetition-rate-switch pulse operation in a Yb-doped fiber laser based on a polarization rotation vector soliton. The polarization controller (PC) in a fiber loop and a polarization-dependent isolator at the output port are incorporated into the laser resonator at the switch of the repetition rate. By adjusting the PC in the cavity, the mode locking can be switched between the fundamental repetition rate and half of it with a tiny pulse width change.

High coupling efficiency technology of large core hollow-core fiber with single mode fiber.

With the research of hollow-core fiber with large core diameter, the coupling efficiency from hollow-core fiber with large core diameter to single-mode fiber is difficult to increase through the traditional technology, we proposed a novel coupling method to improve the coupling efficiency by attaching a pure silica small ball at the front end of single-mode fiber, the coupling efficiency of 50% from hollow-core fiber with a large core diameter of 110 µm to single-mode fiber can be achieved.

Mitigation of mode instability in laser oscillators based on deuterium loading.

Ytterbium-doped fiber (YDF) loaded with deuterium is used herein to mitigate mode instability. Experimental results reveal that this method can increase the mode instability threshold in a laser oscillator. Specifically, when the YDF was loaded with deuterium over two- and four-week periods, the mode instability threshold power increased from ∼459 W to ∼533 W (16%) and to ∼622 W (35%), respectively, but the respective laser efficiencies were almost unaffected (71.

Double negative curvature anti-resonance hollow core fiber.

We report on a double negative curvature anti-resonance hollow core fiber, in which, the cladding is constituted of 6 large tubes and 6 small tubes arranged in a staggered pattern. The simulation shows that the loss of the fiber can reach or even exceed the loss of double-clad negative curvature anti-resonance hollow core fibers in short wavelength band, due to the staggered arrangement of two kind of tubes and the double negative curvature on the core boundary. The best single mode performance with a loss ratio as high as 100,000 between LP mode and LP mode is obtained due to simultaneously inhibited LP modes and LP modes in the fiber structure.

Temperature-Insensitive Refractive Index Sensor with Etched Microstructure Fiber.

A Mach-Zehnder interferometer (MZI) based on an etched all-solid microstructure fiber (MOF) has been demonstrated. The MZI works on the basis of interference between the vibrant core and cladding modes in the MOF. The all-solid MOF has a heterostructure cladding composed of Ge-doped rod arrays and pure silica, and thus can support and propagate a vibrant cladding mode with a large mode area.

Numerical investigation of GHz repetition rate fundamentally mode-locked all-fiber lasers.

GHz repetition rate fundamentally mode-locked lasers have attracted great interest for a variety of scientific and practical applications. A passively mode-locked laser in all-fiber format has the advantages of high stability, maintenance-free operation, super compactness, and reliability. In this paper, we present numerical investigation on passive mode-locking of all-fiber lasers operating at repetition rates of 1-20 GHz.

Robust Q-switching based on stimulated Brillouin scattering assisted by Fabry-Perot interference.

Q-switching operation based on stimulated Brillouin scattering (SBS) has been developed for decades due to its inexpensive configuration, high pulse energy output, and the potential to be free from wavelength and material limitations. However, unstable and uncontrollable pulse output affected by SBS's stochastic nature hinders its development. In this work, we demonstrated a unique robust SBS-based Q-switched all-fiber laser.

Confined-doped fiber for effective mode control fabricated by MCVD process.

A confined-doped fiber was fabricated by a modified chemical vapor deposition (MCVD) process based on refractive index matching technology. With theory and experiments, we compared the confined-doped fiber and normal-doped fiber. We found that the confined-doped fiber with a core of 35 μm and 0.

Design and fabrication of a heterostructured cladding solid-core photonic bandgap fiber for construction of Mach-Zehnder interferometer and high sensitive curvature sensor.

A heterostructured cladding solid-core photonic bandgap fiber (HCSC-PBGF) is designed and fabricated which supports strong core mode and cladding mode transmission in a wide bandgap. An in-line Mach-Zehnder interferometer (MZI) curvature sensor is constructed by splicing single mode fibers at both ends of a HCSC-PBGF. Theoretical analysis of this heterostructured cladding design has been implemented, and the simulation results are consistent with experiment results.

Radical passive bleaching of Tm-doped silica fiber with deuterium.

We demonstrate the almost complete 2 µm laser power recovery of the gamma-ray-irradiated thulium (Tm)-doped silica fiber under deuterium loading. The optical-optical slope efficiency and the cladding absorption spectra of the Tm-doped fiber with gamma-ray irradiation and deuterium treatment have been measured for comparison. It was found that the slope efficiency of the irradiated Tm-doped fiber could be recovered to 96.

Single transverse mode laser in a center-sunken and cladding-trenched Yb-doped fiber.

We report a novel center-sunken and cladding-trenched Yb-doped fiber, which was fabricated by a modified chemical vapor deposition process with a solution-doping technique. The simulation results showed that the fiber with a core diameter of 40 µm and a numerical aperture of 0.043 has a 1217 µm effective mode area at 1080 nm.

Passively Q-switched Yb-doped all-fiber ring laser based on SBS feedback.

We report on a passively Q-switched Yb-doped all-fiber (YDF) ring laser based on stimulated Brillouin scattering (SBS) feedback in a 20-m single-mode fiber (SMF). The Q-switched pulses are generated from the Stokes pulses of SBS and amplified in the YDF. The 10-ns self-Q-switched pulses with ∼1  kW maximum peak power are obtained.

Mitigation of photodarkening effect in Yb-doped fiber through Na ions doping.

In this work, Na ions doping into the Yb-doped fiber is proposed to improve the photo-darkening resistance. The results show that the photo-darkening induced excess loss at equilibrium state at 633nm, 702 nm, 810 nm, and 1041 nm is 115.54dB/m, 86.

All fiber M-Z interferometer for high temperature sensing based on a hetero-structured cladding solid-core photonic bandgap fiber.

We proposed and experimentally demonstrated a high temperature fiber sensor using a hetero-structured cladding solid-core photonic bandgap fiber (HCSC-PBGF) for the first time to our knowledge. A hetero-structured cladding solid-core photonic bandgap fiber is designed and fabricated that supports vibrant core mode and cladding mode transmission. Then, an all fiber M-Z interference sensor is constructed by splicing single mode fiber at both ends of HCSC-PBGF without any other micromachining.

Yb³⁺-doped large core silica fiber for fiber laser prepared by glass phase-separation technology.

We report on the preparation and optical characteristics of an Yb(3+)-doped large core silica fiber with the active core prepared from nanoporous silica rod by the glass phase-separation technology. The measurements show that the fiber has an Yb(3+) concentration of 9811 ppm by weight, a low background attenuation of 0.02 dB/m, and absorption from Yb(3+) about 5.

Active radiation hardening of Tm-doped silica fiber based on pump bleaching.

Tm-doped fiber laser or amplifier can be applied in varied adverse environments. In this work, we demonstrate the pump bleaching of Tm-doped silica fiber with 793nm pump source under gamma-ray irradiation in the range 50Gy-675Gy. The recovery time, the fiber slope efficiency and the fiber cladding absorption spectra after irradiation and bleaching have been measured.

Sclerectomy with nanojoule energy level per pulse by femtosecond fiber laser in vitro.

The use of nanojoule femtosecond pulses (NFP) for highly precise proceeding in anti-glaucoma surgery was evaluated. According to the observation of scanning electron microscopy (SEM), four types of incision patterns, including subsurface, slit-like, spot and cuboid ablations, were accomplished on in vitro sclera by NFP with little collateral damage. In comparison to microjoule femtosecond pulses (MFP), NFP can make extremely precise incisions with smoother inner surface with less peak power density.