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Mode locked fiber ring laser using graphene nanoparticles as saturable absorbers to compress the pulse width has been studied. An experimental method to demonstrate the generation of pulse train with 50 GHz repetition rate with an ultrashort pulse width has been demonstrated. This method uses a combination of rational harmonic mode-locking (RHML) and a saturable absorber in the fiber ring laser. The pulse width using saturable absorbers is shorter by about a factor of 2 compared to that without a saturable absorber. Pulse generation using fiber ring laser with a saturable absorber has been analyzed. The experimental results are in agreement with the results from the simulation.

Optical pulses at high repetition rates are generated using rational harmonic mode locking and saturable absorber made of graphene nanoparticles in a fiber laser. The pulse generation from the fiber laser is modeled by solving the Generalized Nonlinear Schrodinger Equation. The computation involved varying the various saturable absorption parameters, such as linear and nonlinear absorption coefficients. Experimentally stable pulse trains at 20 GHz and 50 GHz are generated with a pulse width of ∼ 2.7 ps. This result agrees with the simulation.

A 30-GHz pulse-train is generated using the rational harmonic mode-locking technique, experimentally, using a Mach–Zehnder Lithium Niobate modulator. The width of the pulses is then reduced from 5.8-ps to 1.9-ps by incorporating nonlinear polarization rotation. This phenomenon arises due to the very high nonlinear behavior of the photonic crystal fiber (PCF) added to the ring laser cavity. Numerically solving the Generalized Nonlinear Schrödinger Equation provided insights into the pulse evolution behavior. The relative polarization angle and length of the PCF were varied to study their effects on the pulse-width.

The single cavity all-dielectric thin film Fabry–Perot filter (s-AFPF) has been theoretically investigated in this paper as a means of tuning the wavelength in an external cavity diode laser (ECDL), and the means of limiting longitudinal mode hopping has been also theoretically investigated. When a TE or TM plane wave irradiates an s-AFPF, a quasi-linear relationship is found in a certain wavelength range between the optical intensity peak transmittance wavelength of s-AFPF and the cosine value of plane wave incident angle at s-AFPF. Based on this feature, we proposed and theoretically investigated an ECDL configuration based on an s-AFPF. By theoretical calculation, the actuator flat edge against the steel ball may be replaced by a bent edge to convert the mode-hop wavelength region into mode-hop-free wavelength region. The ECDL can be used in the application of environmental monitoring, atomic and molecular laser spectroscopy research, precise measurements, and so on.

Mode locked fiber ring laser using graphene nanoparticles as saturable absorbers to compress the pulse width has been studied. An experimental method to demonstrate the generation of pulse train with 50 GHz repetition rate with an ultrashort pulse width has been demonstrated. This method uses a combination of rational harmonic mode-locking (RHML) and a saturable absorber in the fiber ring laser. The pulse width using saturable absorbers is shorter by about a factor of 2 compared to that without a saturable absorber. Pulse generation using fiber ring laser with a saturable absorber has been analyzed. The experimental results are in agreement with the results from the simulation.

Optical pulses at high repetition rates are generated using rational harmonic mode locking and saturable absorber made of graphene nanoparticles in a fiber laser. The pulse generation from the fiber laser is modeled by solving the Generalized Nonlinear Schrodinger Equation. The computation involved varying the various saturable absorption parameters, such as linear and nonlinear absorption coefficients. Experimentally stable pulse trains at 20 GHz and 50 GHz are generated with a pulse width of ∼ 2.7 ps. This result agrees with the simulation.

A 30-GHz pulse-train is generated using the rational harmonic mode-locking technique, experimentally, using a Mach–Zehnder Lithium Niobate modulator. The width of the pulses is then reduced from 5.8-ps to 1.9-ps by incorporating nonlinear polarization rotation. This phenomenon arises due to the very high nonlinear behavior of the photonic crystal fiber (PCF) added to the ring laser cavity. Numerically solving the Generalized Nonlinear Schrödinger Equation provided insights into the pulse evolution behavior. The relative polarization angle and length of the PCF were varied to study their effects on the pulse-width.

An actively harmonic mode-locked fiber ring laser was constructed and its stability was analyzed. A chaotic behavior in the actively harmonic mode locked fiber ring laser was observed.

We discuss an approach for generating optical combs using four-wave mixing process in a nonlinear whispering gallery mode resonator. We show that pumping the resonator with strong enough continuous wave coherent light results in appearance of optical sidebands around the optical carrier. The pumping threshold of the oscillation can be in a few microWatt range for resonators with an ultra-high quality factor. Natural cascading of the the nonlinear process leads to mode locking of the sidebands and emergence of an optical frequency comb. Demodulation of the comb by means of a fast photodiode produces a high frequency spectrally pure RF signal, the frequency of which is given by the resonator morphology.