RESUMEN
We demonstrate an all-fiber ytterbium (Yb)-doped mode-locked oscillator using a hybrid structure based on no-core fiber graded-index multimode fiber (NCF-GIMF) as the saturable absorber (SA). The proposed SA exhibits unique characteristics such as large-power tolerance, high modulation depth of 24.7%, and low saturation intensity of 11.01MW/cm2, which help to achieve a stable mode-locking operation. The all-normal and self-starting oscillator generates stable ultrafast pulses with a repetition rate of 21.35 MHz, pulse energy/average output power of 120 pJ/2.7 mW, and a pulse duration of 2.4 ps at a central wavelength of 1034.2 nm. The output pulses are then dechirped to 300 fs using an external grating compressor and possess high stability with a radio frequency spectrum of 58 dB. These results show that the NCF-GIMF-based SA can be used as an effective photonic device for high energy wave breaking free pulse generation.
RESUMEN
We report a polarization maintaining chalcogenide (ChG) photonic quasicrystal fiber (PQF) for wide-band mid-IR (MIR) supercontinuum (SC) generation. The numerical demonstration of SC generation in the proposed PQF spans from 2 to 15 µm wavelengths for a pulse power of 2 kW. Besides, the proposed PQF offers a high birefringence (10-3 to 10-2) from 3.5 to 15 µm wavelengths and exhibits a low confinement loss (10-7 to 10-1) for the wavelengths from 2 to 15 µm with single mode behavior. The proposed Ge11.5As24Se64.5 PQF is designed with zero dispersion wavelengths (ZDWs) at 4.33 and 4.46 µm for X and Y polarized modes within the wavelength range of 2-15 µm. The polarized spectral broadening of the continuum is realized for the first time from 2 to 15 µm using the proposed PQF with a length of 8 mm. Hence, the two orthogonally polarized modes allow the high degree of freedom in tuning the properties of the SC. Thus, the proposed PQF-based SC source is a good candidate for applications such as optical sensing, frequency metrology, and optical tomography.
RESUMEN
We demonstrate a Q-switched erbium-doped fiber laser using tungsten disulfide (WS2) as a saturable absorber. The WS2 is deposited onto fiber ferrules using a drop-casting method. Passive Q-switched pulses operating in the C-band region with a central wavelength of 1560.7 nm are successfully generated by a tunable pulse repetition rate ranging from 27.2 to 84.8 kHz when pump power is increased from 40 to 220 mW. At the same time, the pulse width decreases from a maximum value of 3.84 µs to a minimum value of 1.44 µs. The signal-to-noise ratio gives a stable value of 43.7 dB. The modulation depth and saturation intensity are measured to be 0.99% and 36.2 MW/cm², respectively.
RESUMEN
We design photonic quasi-crystal fibers (PQFs) of six-, eight-, ten-, and twelve-folds for determining the optimized efficiency as well as the bandwidth of second harmonic generation (SHG). We report a maximum SHG relative efficiency of 941.36% W⻹ cm⻲ for a twelve-fold PQF of 2 µm pitch. The detailed numerical results reveal that, while the relative efficiency increases appreciably, the phase-matching bandwidth increases marginally, as and when the number of folds increases. As the primary interest of this work is to enhance the relative efficiency, we focus our analysis with a twelve-fold PQF for which the efficiency turns a maximum. In line with the practical feasibility of poling, we keep the pitch at 7 µm and report an optimized relative efficiency and phase-matching bandwidth as 95.28% W⻹ cm⻲ and 50.51 nm.cm, respectively.