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In this paper, we propose nanodiamond (ND) material as a saturable absorber (SA) to generate short pulses from a mode-locked erbium-doped fiber laser (EDFL). The ND-SA is fabricated by the drop-casting method using polyvinyledenedifluoride–trifluoroethylene as a host polymer and methyl ethel ketone as a solvent liquid. The SA, which possesses 20% ND concentration, has a 5.46% modulation depth with 2000 M W / c m 2 saturation intensity. Sequentially, the performance of the EDFL is investigated after integrating an ND-SA within the laser ring. The results reveal that the presented ND-SAs produce stable ultrashort laser pulses. Moreover, the fabricated ND film is a promising solid film for many photonic schemes. The proposed mode-locked EDFL-based ND-SA starts a mode-locking operation at a pumped power of 116 mW. The generated mode-locked pulses have a pulse duration of 0.84 ps, a repetition rate of 1.93 MHz, and a power of 0.517 mW, at a pumped power of 187 mW. Finally, to the best of our knowledge, this is the first time that the ND-SA has been used as a mode locker within the EDFL as a thin film and with the suggested fabrication method.

Recently, graphene has been considered as great candidate to be applied as the saturable absorber (SA) with its brilliant optical characteristics such as ultrafast recovery time and ultra-wideband absorption due to its zero bandgap energy and linear dispersion of Dirac electrons. This paper focuses on reviewing the generation of short pulses from passive mode-locked fiber lasers that employ graphene-based saturable absorber (GBSA). Various parameters that make it excellent for generation ultra-short pulsed including modulation depth, nonlinearity, saturation intensity, self-amplitude modulation, its crystal lattice structure, band gap energy distribution are discuss in details. Furthermore, comparison between single layers and multilayer GBSA is made to explain the effect of layers number on the behaviour of SA in ring cavity fiber lasers.

In this paper, it is demonstrated by means of simulations, the practical feasibility of a transmission filter implemented from a stack of high and low index birefringent thin films. Simulations were carried out with a software toolbox package implemented as Matlab™ m-files.The following materials were used ( ZnSe, GaAs, BaF2) as coating materials and KB7 glass as substrate material .In this paper it can be study the designing of transmission filter with two ,three or four Fabry-Perot resonators (FPRs) structure .The difference between each one of them show how the number of multi-stack layer belonging to each FPRs affect on the spectral properties of transmission filter and effect on the choosing of coating material on the properties of transmission filter .Results show that transmission filter of multi-FPRs results in narrowing the transmittance band and making it somewhat flatter at its top from the single one. But if it has multi-FPRs structure with equal length , the band becomes flatter than that of transmission filter with single FPR structure but exhibits some ripples.The difference between the values of refractive index of multi layer stack has great influence on the transmittance value, the spectral properties and number of peaks in the transmittance spectrum of the transmission filter as shown in the simulated figures.