Rodrigo Amezcua-Correa

Control of surface modes in low loss hollow-core photonic bandgap fibers

We report low-loss hollow-core photonic bandgap fibers free from surface modes. They have low attenuation over the full spectral width of the bandgap, and approximately halved dispersion and dispersion slope compared to previous fibers.

Modal interferometer based on hollow-core photonic crystal fiber for strain and temperature measurement

In this work, sensitivity to strain and temperature of a sensor relying on modal interferometry in hollow-core photonic crystal fibers is studied. The sensing structure is simply a piece of hollow-core fiber connected in both ends to standard single mode fiber. An interference pattern that is associated to the interference of light that propagates in the hollow core fundamental mode with light that propagates in other modes is observed. The phase of this interference pattern changes with the measurand interaction, which is the basis for considering this structure for sensing. The phase recovery is performed using a white light interferometric technique. Resolutions of +/- 1.4 microepsilon and +/- 0.2 degrees C were achieved for strain and temperature, respectively. It was also found that the fiber structure is not sensitive to curvature.

A phase-stabilized carbon nanotube fiber laser frequency comb

A frequency comb generated by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber is phase-stabilized for the first time. Measurements of the in-loop phase noise show an integrated phase error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb is compared with a CW laser near 1533 nm stabilized to the nu(1) + nu(3) overtone transition in an acetylene-filled kagome photonic crystal fiber reference, while the CW laser is simultaneously compared to another frequency comb based on a Cr:Forsterite laser. These measurements demonstrate that the stability of a GPS-disciplined Rb clock is transferred to the comb, resulting in an upper limit on the locked combs frequency instability of 1.2 x 10(-11) in 1 s, and a relative instability of <3 x 10(-12) in 1 s. The carbon nanotube laser frequency comb offers much promise as a robust and inexpensive all-fiber frequency comb with potential for scaling to higher repetition frequencies.

Remote System for Detection of Low-Levels of Methane Based on Photonic Crystal Fibres and Wavelength Modulation Spectroscopy

In this work we described an optical fibre sensing system for detecting low levels of methane. The properties of hollow-core photonic crystal fibres are explored to have a sensing head with favourable characteristics for gas sensing, particularly in what concerns intrinsic readout sensitivity and gas diffusion time in the sensing structure. The sensor interrogation was performed applying the Wavelength Modulation Spectroscopy technique, and a portable measurement unit was developed with performance suitable for remote detection of low levels of methane. This portable system has the capacity to simultaneously interrogate four remote photonic crystal fibre sensing heads.

In-Line Gas Sensor Based on a Photonic Bandgap Fiber With Laser-Drilled Lateral Microchannels

The fabrication, characterization, and gas sensor application of a hollow core photonic bandgap fiber (HC-PBGF) with laser drilled lateral microchannels will be described. The HC-PBGF was tailor-made for gas sensing applications in the near infrared region from 1.5 to 1.7 μm wavelengths, covering the first harmonic absorptions of quite a number of natural gas components. Laser-drilled, lateral microchannels makes access to the light guiding core of the HC-PBGF and offers the ability to realize fast-responding, distributed gas sensor cells with large optical path lengths. The application of those cells in a distributed sensor arrangement using white light spectroscopy combined with chemometrical methods as interrogation method will be demonstrated.

Distributed gas sensor based on a photonic bandgap fiber cell with laser-drilled, lateral microchannels

The fabrication, characterization, and use of a laser-drilled hollow core photonic band gap fiber (HC-PBGF) as a gas sensor in the near infrared region, from 1.5 μm to 1.7 μm wavelengths, are discussed. HC- PBGFs with laser-drilled, lateral micro channels have the ability to realize fast-responding, distributed gas sensor cells with large optical path lengths. By using white light spectroscopy as a sensor interrogation method, together with chemometric methods, not only the detection of individual gases but also the quantification of composed gas mixtures is possible.

Gas sensing with suspended core fibres and hollow core band gap fibres: a comparative study

The usability, advantages and limitations of suspended core fibres and hollow core band gap fibres for gas sensing in the NIR will be discussed and demonstrated. Suspended core fibres of various geometries and hollow core photonic band gap fibres with different transmission properties have been investigated with respect to their relative sensitivity and their usable spectral bandwidth, using combustion gases as test substances. It has been found that, despite of the more than an order lower sensitivity of suspended core fibers, both kinds of fibre may found use in different practical gas sensing applications.

Sensing characteristics of hollow-core photonic crystal fibre modal interferometers

In this work, sensitivity to strain, temperature and curvature of a sensor relying on modal interferometry in hollow-core photonic crystal fibre is studied. The sensing structure is simply a piece of hollow-core fibre connected in both ends to standard single mode fibre. An interference pattern that is associated to the interference of the light that propagates in the hollow core fundamental mode with light that propagates in other modes is observed. The phase of this interference pattern changes with the measurand interaction, which is the basis for considering this structure for sensing. The phase recovery is performed using a white light interferometric technique.

Control of surface modes in hollow-core bandgap fibers

In this paper we report on the fabrication and characterization of hollow core photonic bandgap fibers that do not suffer from surface mode coupling. This enables low loss over the full spectral width of the photonic bandgap formed in the cladding. It also enables reduced dispersion slope, which is a key parameter for several applications of these fibers to high-power ultrashort pulse compression.