RESUMO
A laser mode-locking phenomenon based on polarization-dependent loss (PDL) using a passive fiber coil is demonstrated. We propose using a fiber coil operating in low-V-number regime to achieve an enhanced bend-induced PDL and to maintain a reasonable bend loss. A mode-locked thulium doped all-fiber laser is shown using the low-V-number fiber coil. The results indicate that a moderate amount of PDL at 1 dB is sufficient to initiate and sustain a stable CW mode-locking operation. To the best of our knowledge, this is the first demonstration of a CW mode-locked fiber laser based on PDL enabled by a fiber coil.
RESUMO
We demonstrate for the first time, to the best of our knowledge, a thulium-doped, all-fiber, mode-locked laser using a carbon nanotube saturable absorber, operating in the dissipative-soliton regime and the stretched-pulse-soliton regime. The net dispersion of the laser cavity is adjusted by inserting different lengths of normal dispersion fiber, resulting in different mode-locking regimes. These results could serve as a foundation for the optimization of mode-locked fiber-laser cavity design at the 2 µm wavelength region.
RESUMO
Present day strategies for delivery of wireless photodynamic therapy (PDT) to deep-seated targets are limited by the inadequacy of irradiance and insufficient therapeutic depth. Here we report the design and preclinical validation of a flexible wireless upconversion nanoparticle (UCNP) implant (SIRIUS) that is capable of large field, high intensity illumination for PDT of deep-seated tumors. The implant achieves this by incorporating submicrometer core-shell-shell NaYF4 UCNPs into its design, which significantly enhances upconversion efficiency and mitigates light loss from surface quenching. We demonstrate the efficacy of SIRIUS UCNP implant mediated PDT in preclinical breast cancer disease models. In our in vitro experiments, SIRIUS directed 5-Aminolevulinic Acid (5-ALA) based wireless PDT leads to significant reactive oxygen species (ROS) generation and tumor apoptosis in hormonal receptor+/HER2+ (MCF7) and triple-negative (MDA-MB-231) breast cancer cell lines. In our in vivo rodent model, SIRIUS-driven PDT is shown to be significant in regressing tumors when applied to orthotopically inoculated breast tumors. Following successful preclinical validation, we also describe a clinical prototype of UCNP breast implant with potential dual cosmetic and onco-therapeutic functions. SIRIUS is an upconversion breast implant for wireless PDT that fulfils all the design prerequisites necessary for seamless clinical translation.
Assuntos
Implantes de Mama , Nanopartículas , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Ácido Aminolevulínico , Linhagem Celular TumoralRESUMO
17.2 GHz, the highest fundamental-mode repetition rate to our knowledge, of a carbon nanotube-based passively mode-locked laser is realized at 1570 nm by employing purified single-walled carbon nanotubes as saturable absorbers. The ultrashort linear laser cavity configured with a approximately 9 mm length is designed and demonstrated with our extremely miniaturized nanotube mode locker and a mirror-coated semiconductor optical amplifier as gain medium. The demonstrated pulsed laser has the inferred temporal pulse width of 14 ps and a 3 dB spectral bandwidth of 0.73 nm.
RESUMO
We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.
RESUMO
We design single-wall carbon nanotube (SWNT) thin-film saturable absorbers (SAs) integrated onto semiconductor distributed Bragg reflectors for mode-locking solid-state Er:Yb:glass lasers. We characterize the low nonsaturable loss, high-damage-threshold SWNT SAs and verify their operation up to a pulse fluence of 2 mJ/cm(2). We demonstrate passive fundamental continuous-wave mode locking with and without group-delay dispersion compensation. Without compensation the laser produces chirped 1.8 ps pulses with a spectral width of 3.8 nm. With compensation, we obtain 261 fs Fourier-transform-limited pulses with a spectral width of 9.6 nm.