Rodrigo M. Gerosa

Efficient and short-range light coupling to index-matched liquid-filled hole in a solid-core photonic crystal fiber

A photonic crystal fiber (PCF) with a section of one of the holes next to the solid core filled with an index-matched liquid is studied. Liquid filling alters the core geometry, which locally comprises the original silica core, the liquid channel and the silica around it. It is demonstrated that when light reaches the filled section, it periodically and efficiently couples to the liquid, via the excitation of a number of modes of the composite core, with coupling lengths ranging from tens to hundreds of microns. The resulting modal-interference-modulated spectrum shows temperature sensitivity as high as 5.35 nm/°C. The proposed waveguide geometry presents itself as an interesting way to pump and/or to probe liquid media within the fiber, combining advantages usually found separately in liquid-filled hollow-core PCFs (high light-liquid overlap) and in solid-core PCFs (low insertion losses). Therefore, pumping and luminescence guiding with a PCF filled with a Rhodamine solution is also demonstrated.

Selectively coupling core pairs in multicore photonic crystal fibers: optical couplers, filters and polarization splitters for space-division-multiplexed transmission systems

Selective coupling a single pair of cores in a photonic crystal fiber with multiple, initially decoupled, cores is demonstrated through the use of a technique to locally post-process the fiber cross section. Coupling occurs when the hole between the selected core pair is collapsed over a short fiber section, which is accomplished by heating the section while the hole is submitted to an air pressure that is lower than that applied to all other holes in the microstructure. The demonstrated couplers present an estimated insertion loss of ~1 dB and exhibit spectral modulations with a depth of up to 18 dB and a high polarization sensitivity that can be exploited for polarization splitting or filtering in space-division-multiplexed optical interconnection and telecommunication links.

All-fiber high-flow microfluidic dye laser

An all-fiber dye laser is demonstrated. The dye solution is kept under flow, allowing for high repetition rate pumping. Threshold average pump power of 2.15 mW and conversion slope efficiency of ~8.5% are achieved.

Graphene oxide and reduced graphene oxide as saturable absorbers onto D-shaped fibers for sub 200-fs EDFL mode-locking

We present high mode-locking performances from an erbium-doped fiber laser (EDFL) by using graphene oxide (GO) and reduced graphene oxide (r-GO) as saturable absorbers (SA) deposited onto the polished surface of a D-shaped optical fiber. The samples were prepared with different concentrations and its characterization was performed by using an optical microscope, a Raman spectrometer, nonlinear saturable absorption measurements, polarization setup, and laser mode-locking analysis. As a 1550-nm polarizer, the best GO (r-GO) samples exhibited higher polarization extinction ratio (PER) of 7.94 (7.65) dB, corresponding to 84 (83) %, both showing similar graphene TE absorption behavior. In a managed-intracavity dispersion laser, broadest bandwidths of 27.2 and 24.1 nm and the corresponding shortest pulse duration of 190 fs could be generated when incorporating the SA with high modulation depth (above 20%), being so far the best mode-locking results ever reported in the literature for GO and r-GO SA onto D-shaped optical fibers in EDFL.

Corrections to "Temperature Sensing Using Colloidal-Core Photonic Crystal Fiber" [Jan 12 195-200]

In the above-named work [ibid., vol. 12, no. 1, pp. 195-200, Jan. 2012], the financial support was omitted from the footnote on page 195. It should read as follows. This work was supported by Fundo Mackenzie de Pesquisa, FINEP, CAPES, CNPq, NANOFOTON and FOTONICOM.

Post-processing multicore photonic crystal fibers for locally coupling selected core pairs

Coupling selected cores among otherwise decoupled multiple cores in photonic crystal fibers is demonstrated via the use of differential pressure and heat for local processing. Complex interferometer assemblies for all-fiber devices may be achieved.

Sub-300fs mode-locked erbium doped fiber laser using graphene oxide and reduced graphene oxide onto D-shaped optical fibers

We present the ultrashort pulse generation of sub-300 fs from a mode-locked Erbium doped fiber laser by using spin-coated graphene oxide and reduced graphene oxide saturable absorbers deposited onto polished surface of D-shaped optical fibers.

Modification of a photonic crystal fiber by selective collapse of the microstructure holes

In this paper, an optical fiber post-processing rig is described, as well as its use for collapsing selected holes in the microstructure of a photonic crystal fiber. As a result, discrete devices can be designed and fabricated. A PCF with the ring of holes nearest to the core locally collapsed is shown to operate as a modal Mach-Zehnder interferometer with a 35-nm spectral period and an 8-dB modulation depth. We also demonstrate the capability of producing complex structures, with the letter “M” inscribed in a PCF through the collapse of the selected holes.