All-fiber CW cylindrical vector beam fiber laser based on few-mode fiber Bragg grating

An all-fiber CW cylindrical vector beam (CVB) fiber laser based on a few-mode fiber Bragg grating (FW-FBG) with switchable radially and azimuthally polarized beam generation has been demonstrated. The CVB fiber laser operates at a wavelength of 1053.95 nm with a 3 dB line width of 0.1 nm, a signal-to-background ratio of more than 50 dB. The CVB output power can reach 75 mW, and the mode purity is measured to be >95.5%. This compact CVB fiber laser has potential applications in many areas such as optical tweezers, optical trapping and optical sensing systems

Optical property of few-mode fiber with non-uniform refractive index for cylindrical vector beam generation

This paper investigates optical properties of few-mode fiber with non-uniform refractive index, namely: the few mode fiber with U-shape refractive index and the two-mode and four-mode few-mode fiber with bent radius. Finite element method is used to analyze the mode distributions based on their non-uniform refractive index. Effective mode control can be achieved through these few mode fibers to achieve vector beam generation. Finally, reflection spectra of a few-mode fiber Bragg grating are calculated theoretically and then measured under different bending conditions. Experimental results are in good accordance with the theoretical ones. These few mode fibers show potential applications in generation of cylindrical vector beam both for optical lasing and sensing systems

Switchable dual-wavelength cylindrical vector beam generation from a passively mode-locked fiber laser based on carbon nanotubes

Cylindrical vector beams (CVBs) with axial symmetry in both polarization and field intensity have attracted much attention because of their unique optical properties. Conventional methods to obtain CVBs including direct modulation of light beams in free space and high-order mode excitation by offset splicing single-mode fiber (SMF) with few-mode fiber (FMF) usually works at single wavelength with rather narrow bandwidth. Here, for the first time to the best of our knowledge, we demonstrate switchable dual-wavelength CVB generation from a passively mode-locked fiber laser using carbon nanotubes (CNTs) as saturable absorber for mode-locking and a home-made mode-selective coupler (MSC) as both mode converter and birefringence filter. In experiments, the mode-locked fiber laser delivers CVB pulses of dual-wavelength (1532.5 nm, 1555.5 nm) and corresponding single wavelength with duration of hundreds of femtosecond, respectively. Moreover, the output polarization status is switchable between radially and azimuthally polarized states. The mode-locked CVBs with wavelength and polarization flexibility may have potential applications in mode-division multiplexing optical fiber communication, nanoparticle manipulation, material processing, nonlinear optics, and so on

Simvastatin suppresses cerebral aneurysm in rats through suppression of release of pro-inflammatory cytokines

Purpose: To investigate the protective effect of simvastatin (SA) against onset of cerebral aneurysmmediated inflammatory cytokine release and subsequent inflammation and degradation of the extracellular matrix of smooth muscle cells.Methods: Cerebral aneurysm was induced in male Wistar rats using elastase injection, and aneurysm growth was monitored for one month following SA treatment. Inhibition of aneurysm growth was determined along with the expression levels of chemokines and pro-inflammatory cytokines, including TNF-α, IL-8, IL-1β, IL-17, IL-6, macrophage chemoattractant protein-1 (MCP-1), and matrix metalloproteinases 2 and 9, using enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR).Results: Aneurysm size decreased in rats treated with SA, relative to values obtained for control rats (p < 0.05). The corresponding expressions of inflammatory cytokines and chemokines were also reduced following pre-treatment with SA (p < 0.05). The results indicate a reduction in the aneurysm area in rats pre-treated with SA, when compared to the untreated animals (p < 0.05).Conclusion: SA treatment inhibits the progression of cerebral aneurysms via its protective effect against inflammation, indicating its potential for use in the prevention and treatment of cerebralaneurysms

Mode and wavelength-switchable pulsed fiber laser with few-mode fiber grating

We propose and demonstrate a mode and wavelength-switchable pulsed fiber laser using two-mode fiber Bragg grating (TM-FBG) as both transverse mode converter and wavelength selector. The mode-locking mechanism is based on saturable absorption of semiconductor saturable absorption mirror (SESAM). Due to the use of low polarization-dependent mode-locking method, polarization disturbation between mode-locking and transverse-mode selection has been effectively eliminated, thus enabling flexible transverse-mode selection with simultaneous mode-locking operation. Moreover, through the optimized offset launching technique, this laser can operate at the wavelengths of the fundamental mode (LP01) and second-order mode (LP11), and thus export cylindrical vector beams (CVBs) and fundamental mode beams at the TM-FBG output port, respectively. This all-fiber laser is a simple, low-cost and flexible source for mode-division multiplexing system and other applications