H. G. Rosa

Transfer of an exfoliated monolayer graphene flake onto an optical fiber end face for erbium-doped fiber laser mode-locking

This paper presents, for the first time, the successful transfer of exfoliated monolayer graphene flake to the optical fiber end face and alignment to its core. By fabricating and optimizing a polymeric poly(methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) substrate, it is possible to obtain a contrast of up to 11% for green light illumination, allowing the identification of monolayer graphene flakes that were transferred to optical fiber samples and aligned to its core. With Raman spectroscopy, it is demonstrated that graphene flake completely covers the optical fiber core, and its quality remains unaltered after the transfer. The generation of mode-locked erbium-doped fiber laser pulses, with a duration of 672 fs, with a single-monolayer graphene flake as a saturable absorber, is demonstrated for the first time. This transfer technique is of general applicability and can be used for other two-dimensional (2D) exfoliated materials.

Explaining simultaneous dual-band carbon nanotube mode-locking Erbium-doped fiber laser by net gain cross section variation

In this paper we report the pulse evolution of a simultaneously mode-locked Erbium-doped fiber laser at 1556-nm-band and 1533-nm-band. We explain the dual wavelength laser operation by means of net gain cross section variations caused by the population inversion rate dependence on the pump power. At 1556-nm-band, we observed pulse duration of 370 fs with bandwidth of 8.50 nm and, for pump power higher than 150 mW, we observe the rise of a CW and mode-locked laser, sequentially, at 1533-nm-band. We show that both bands are simultaneously mode-locked and operate at different repetition rates.

58 kHz ultra-low repetition rate ultralong Erbium-doped fiber laser mode-locked by carbon nanotubes

In this paper we present a 58 kHz fundamental repetition rate 3.5 km long EDFL mode-locked by SWCNT saturable absorbers. Because laser nonlinearities and accumulated dispersion, we observed chirped soliton-like 6.79 ps pulses with 0.49 nm spectral width. This is the lowest repetition rate in EDFL, to the best of our knowledge.

Raman Mapping Characterization of All-Fiber CVD Monolayer Graphene Saturable Absorbers for Erbium-Doped Fiber Laser Mode Locking

We present a study on the characterization and quality evaluation of all-fiber chemical vapor deposition (CVD) graphene saturable absorber samples for Erbium-doped fiber laser (EDFL) mode locking. Optical fiber end faces covered by CVD graphene were analyzed by Raman spectroscopy, and classification criteria related to graphene Raman bands properties were adopted in order to evaluate samples quality. The analysis revealed that for all samples, the fiber core was 100% covered by graphene, with 88% average monolayer graphene coverage, and 82% low defect graphene coverage. Graphene samples were used as saturable absorbers in EDFL, and soliton-like pulses as short as 599 fs were generated, with average pulse duration of 620 ± 10 fs among all samples.

Thin films incorporating carbon nanotubes used as saturable absorbers to passively mode-lock Erbium-doped fiber lasers

We present a new method to fabricate thin films using single-walled carbon nanotubes and a urethane-based transparent polymer. We construct an Erbium-doped fiber laser to test our films as saturable absorbers to passive mode-lock them. As results, pulse-trains were achieved and we carry on an optimization study about the relation involving cavity length, total cavity dispersion, absorption strength of thin films incorporating SWCNT and laser bandwidth to produce higher bandwidths in passive mode-locking regime.

Erbium-doped fiber laser passively mode-locked by thin films incorporating carbon nanotubes

We fabricate thin films incorporating single-walled carbon nanotubes by a simple method and construct an Erbium-doped fiber laser to test our saturable absorbers to passive mode-lock them. We present a study about total cavity dispersion in mode-locked regime to produce higher bandwidths.

O-band passive mode-locked Raman fiber laser based on Single Wall Carbon Nanotubes as saturable absorbers

We present a passive mode-locked Raman laser incorporating SWCNT (Single-Wall Carbon Nanotubes) as saturable absorbers operating in O-band. We construct two single mode fiber lasers to generate ultrashort pulses near zero dispersion wavelength fiber. As results, pulse-trains were achieved in two different regimes and we compared the output bandwidth, rate repetition and pulse durations from both lasers. With high accumulated dispersion, nanoseconds square duration pulses were generated from laser cavity. So we study the pulse duration behavior introducing a dispersion shifted fiber (DSF) inside the cavity and verified a strong relation between pulse shortening and DSF length.

Multiwavelength and multifunctional Erbium-doped fiber laser based on arrayed waveguide grating

We demonstrated a multiwavelength and multifunctional ring cavity laser based on integration of two Athermal Arrayed Wavelength Gratings (AWG). We demonstrated that both AWG are reversible, and making laser capable to operate simultaneously in continuous wave in one channel and passively mode-locked by single-walled carbon nanotubes in another channel.