RESUMEN
A novel approach to generating 40 GHz narrow linewidth frequency-switched microwave signals is proposed and demonstrated. In this scheme, a single-longitudinal-mode (SLM) double-Brillouin-frequency spaced Brillouin fiber laser with dual-ring configuration and unpumped erbium-doped fiber (EDF) is used to generate dual-wavelength lasers, and a fiber Bragg grating is used to select the laser for different Brillouin frequency spacings. Dual-ring configuration and unpumped EDF are designed to select the mode for the SLM laser. Dual-wavelength lasers are inserted into a photodetector, and microwave signals at 10.66, 21.39, 32.12, or 42.85 GHz can be obtained. The linewidth of the generated microwave signals is less than 69 kHz. The frequency drift at each frequency is less than 0.83 MHz. The frequency noise and linewidth of Stokes signals are measured, and the linewidth broadening effect of microwave signals is analyzed.
RESUMEN
We study a passively mode-locked square-wave pulse (SWP) fiber laser with a nonlinear amplifying loop mirror in the cavity. The net dispersion of the cavity is about 0.68 ps2 and the SWP mode-locked fiber laser can be realized. The peak power of the SWP hardly varies and the pulse duration gets expanded with the increasing pump power. SWPs breaking in the low nonlinear cavity can be observed and the stable dual SWP can be achieved in the experiment. When the total pump power stays at 800 mW, the interval of dual pulses is 41 ns. The widths of dual SWPs are both 1.5 ns. The output power rises linearly with the increasing of the pump power, while the interval of dual SWPs is almost constant. Then, the physical mechanism of the SWP breaking and vector nature of the pulse are analyzed.
RESUMEN
We propose and experimentally investigate a multiwavelength Brillouin fiber laser (MBFL) with triple frequency spacing by employing a modular structure. In this scheme, we obtain nine channels optimized with frequency spacing of 0.259 nm. The single, double, and triple Brillouin frequency spacing for the MBFL can be easily realized by utilizing this modular structure. The impact of Brillouin pump (BP) power, BP wavelength, and erbium-ytterbium-doped fiber amplifier (EYDFA) output power on the performance of the MBFL is investigated, respectively. We also study the generation of beating frequency microwave signals based on single, double, and triple frequency spacing MBFL. 10.5 GHz, 21.48 GHz, and 31.77 GHz microwave signals with 3 dB linewidth of 16.4 MHz, 15.2 MHz, and 12.8 MHz are generated, respectively.
RESUMEN
We propose and experimentally demonstrate a widely tunable mode-locked thulium-doped fiber laser. The laser can operate at both continuous-wave and mode-locked states at different pump power levels. A classic nonlinear polarization rotation structure is employed to obtain the passive mode-locked laser. A birefringence Lyot filter as a fiber comb filter is used to expand the tuning range. Thanks to the filtering component, the tuning range of the continuous-wave laser can reach 127 nm (1823-1950 nm). The tuning ranges of the single-wavelength and dual-wavelength mode-locked lasers are 94 nm (1835-1929 nm) and 87 nm (1831-1918 nm), respectively, with a 3.085 MHz repetition rate and 75 ps pulse width.
RESUMEN
A simple photonic approach to generate microwave frequency switched microwave signal is proposed and experimentally demonstrated. In this scheme, a Brillouin fiber laser with double-Brillouin-frequency spacing is used. The Brillouin ring configuration suppresses incoming Brillouin pump and even-order Stokes signals in the cavity. In addition, it also allows propagation of the odd-order Brillouin Stokes signals from configuration to output coupler. A dual-wavelength optical signal is heterodyned at the high-speed photodetector to produce a microwave signal. Frequency switched microwave signals, at 10.75 and 21.39 GHz, respectively, can be obtained through adjusting the polarization controller (PC) and loss of the variable optical attenuator (VOA).