RESUMEN
We present a broadband wavelength-swept laser using a 16-µm-core-diameter Cr4+:YAG crystal fiber as the gain medium. The laser-diode-pumped crystal fiber laser has a threshold of only 102â mW due to the low propagation loss and high heat dissipation efficiency. The laser achieves a sweeping wavelength range of 134â nm, centered around 1425â nm, with a scanning speed of 163â k nm/s. Notably, the cross-polarization-coupled excited state absorption of the signal wavelength constrained the long-wavelength lasing limit. This laser has the potential for swept source optical coherence tomography applications, providing an axial resolution of 11.4â µm.
RESUMEN
Mode-locked and Q-switched pulsed fiber laser sources with wavelengths of 1.55 µm are widely used in various fields. Gold nanorods (GNRs) have been applied in biomedicine and optics owing to their biocompatibility, easy fabrication, and unique optical properties. This paper presents the analysis of a saturable absorber based on a colloidal gold nanorod (GNR) thin film for dual-function passively mode-locked and Q-switched 1.55-µm fiber lasers. The colloidal GNR thin film possesses superior properties such as a wide operating wavelength range, large nonlinear absorption coefficient, and a picosecond-order recovery time. Its modulation depth and saturation intensity at 1.55 µm are 7.8% and 6.55 MW/cm2, respectively. Passive mode-locked or Q-switched laser operation is achieved by changing the number of GNR thin-film layers. The advantages of these high-quality GNRs in mode-locked and Q-switched fiber lasers with record-high slope efficiency are verified by conducting comprehensive material and laser dynamic analyses. The self-starting mode-locked fiber laser with an efficiency as high as 24.91% and passively Q-switched fiber laser with the maximum energy of 0.403 µJ are successfully demonstrated. This paper presents the novel demonstration of reconfigurable mode-locked and Q-switched all-fiber lasers by incorporating colloidal GNR thin films.
RESUMEN
Based on cascaded Raman scattering, near-infrared (NIR) noise-like pulses (NLPs) were successfully demonstrated using a Yb-doped fiber amplifier system. Through a nonlinear fiber amplifier using a germanium-zirconia-silica Yb3+-doped single mode fiber as a gain fiber, the fourth-order Stokes wave (4th-SW) can be excited to extend the emission peak of approximately 1.2-µm and a 3-dB bandwidth of approximately 130 nm. To further shift the wavelength more efficiently toward 1.3 µm, filtered NLPs with an emission peak at 1075 nm were adopted as seeded pulses to excite the fifth-order Stokes wave (5th-SW) because of the better conversion efficiency of stimulated Raman scattering without gain competition with Yb-doped fiber. The generated NIR NLPs were shown to be an excellent light source for the photoluminescence emission from three photon absorption of perovskite to illustrate the red shift of the emission peak owing to the reabsorption effect.
RESUMEN
A noninvasive method for characterizing Si/Mo thin-film stack thickness and its complex transfer function using common-path optical coherence tomography is proposed, analyzed, and experimentally demonstrated. A laser-produced plasma (LPP)-based extreme ultraviolet (EUV) source was excited by a four-stage nanosecond Yb:fiber laser amplifier with a pulse energy of 1.01 mJ. The tabletop LPP EUV source was compact and stable for generating the EUV interference fringes. The measured complex transfer function of the Si/Mo stack was verified near the pristine 13.5-nm wavelength range.
RESUMEN
We report on the demonstration of a passively Q-switched 1.55 µm fiber laser utilizing a colloidal PbS quantum dot (QD) thin film as a saturable absorber. Colloidal PbS QD films have several features that are advantageous in passively Q-switched fiber laser operation, including a large operation wavelength range, cost-effectiveness, and a low saturable absorption intensity. We conducted thorough material and optical studies to verify the advantages of PbS QDs in Q-switched laser operation and successfully generated 801 nJ pulses with a 24.2 kHz repetition rate. To the best of our knowledge, the developed Q-switched fiber laser is the first based on colloidal PbS QDs.
RESUMEN
Near-infrared supercontinnum (SC) generation, accompanied with several emission bands at visible and ultraviolet, is experimentally investigated in an all-fiber single-mode Yb(3+)-doped silica fiber MOPA. The seed is an all-normal-dispersion mode-locked Yb(3+)-doped single-mode fiber laser using a nonlinear polarization evolution mechanism. With the pump power of several hundreds of milliwatts, SC spanning of 1010 nm to 1600 nm was generated in a 20-m single-mode germano-zirconia-silica Yb(3+)-doped fiber amplifier. The intensive nonlinear effects, namely stimulated Raman scattering, four wave mixing, and self-phase modulation, enable the SC generation in the small-core fiber amplifier without the use of photonic crystal fibers or tapered fibers. Such a compact and cost-effective SC generation system enables applications in optical coherent tomography, optical metrology, and nonlinear microscopy.
