3D reconstruction of complex dielectric function of the glass during the femtosecond micro-fabrication

We measure complex amplitude of scattered wave in the far field, and justify theoretically and numerically solution of the inverse scattering problem. This allows single-shot reconstructing of dielectric function distribution during direct femtosecond laser micro-fabrication.

Evaluation of RF power degradation in microwave photonic systems employing uniform period fibre Bragg gratings

The frequency dependent RF power degradation in direct modulated microwave photonic systems employing uniform period fibre Bragg gratingsFBG.as reflective elements is investigated. The results have implications in terms of the available RF bandwidth and the stability requirements for the fibre Bragg gratings.

3D Reconstruction of the complex dielectric function of glass during femtosecond laser micro-fabrication

We report on a new technique to reconstruct the 3D dielectric function change in transparent dielectric materials and the application of the technique for on-line monitoring of refractive index modification in BK7 glass during direct femtosecond laser microfabrication. The complex optical field scattered from the modified region is measured using two-beam, single-shot interferogram and the distribution of the modified refractive index is reconstructed by numerically solving the inverse scattering problem in Born approximation. The optical configuration suggested is further development of digital holographic microscopy (DHM). It takes advantage of high spatial resolution and almost the same optical paths for both interfering beams, and allows ultrafast time resolution.

A new method for microwave generation and data transmission using DFB laser based on fiber bragg gratings

A novel architecture for microwave/millimeter-wave signal generation and data modulation using a fiber-grating-based distributed feedback laser has been proposed in this letter. For demonstration, a 155.52-Mb/s data stream on a 16.9-GHz subcarrier has been transmitted and recovered successfully. It has been proved that this technology would be of benefit to future microwave data transmission systems. © 2006 IEEE.

A novel all-fiber bipolar transversal filter with complementary outputs

A novel all-fiber bipolar delay line filter is realized in a single-line cascaded high birefringence fiber structure. Optically coherent operation is achieved with suppression of interference noise. Complementary filter outputs give simultaneous lowpass and highpass responses.

Mask-less lithography for fabrication of optical waveguides

A flexible method for fabricating shallow optical waveguides by using femtosecond laser writing of patterns on a metal coated glass substrate followed by ion-exchange is described. This overcomes the drawbacks of low index contrast and high induced stress in waveguides directly written using low-repetition rate ultrafast laser systems. When compared to conventional lithography, the technique is simpler and has advantages in terms of flexibility in the types of structures which can be fabricated.

Chromatic dispersion effect in a microwave photonic filter using superstructured fiber Bragg grating and dispersive fiber

In this paper a microwave photonic filter using superstructured fiber Bragg grating and dispersive fiber is investigated. A theoretical model to describe the transfer function of the filter taking into consideration the spectral width of light source is established. Experiments are carried out to verify the theoretical analysis. Both theoretical and experimental results indicate that due to chromatic dispersion the source spectral width introduces an additional power penalty to the microwave photonic response of the filter.

Mask-less lithography for fabrication of optical waveguides

A flexible method for fabricating shallow optical waveguides by using femtosecond laser writing of patterns on a metal coated glass substrate followed by ion-exchange is described. This overcomes the drawbacks of low index contrast and high induced stress in waveguides directly written using low-repetition rate ultrafast laser systems. When compared to conventional lithography, the technique is simpler and has advantages in terms of flexibility in the types of structures which can be fabricated.

3D reconstruction of complex dielectric function of the glass during the femtosecond micro-fabrication

We measure complex amplitude of scattered wave in the far field, and justify theoretically and numerically solution of the inverse scattering problem. This allows single-shot reconstructing of dielectric function distribution during direct femtosecond laser micro-fabrication.

Surface roughness reduction and diffraction efficiency optimisation for e-beam written phase masks

We report the control of surface relief grating parameters and roughness for phase masks produced using e-beam lithography (EBL) and reactive ion etching (RIE). The relationships between processing conditions, grating parameters, surface roughness and the diffraction efficiency of the zeroth and the two first order transmitted beams are discussed.

Direct cavity assessment and mode optimisation technique for DFB fibre laser

A technique for direct real-time assessment of a distributed feedback fibre laser cavity conditions during operation is demonstrated and used to provide a cavity mode conditioning feedback mechanism to optimise output performance. Negligible wavelength drift is demonstrated over a 52 mW pump power range.

Distributed temperature sensing using a chirped fibre Bragg grating

A fully distributed temperature sensor consisting of a chirped fibre Bragg grating has been demonstrated. By fitting a numerical model of the grating response including temperature change, position and width of localized heating applied to the grating, we achieve measurements of these parameters to within 2.2 K, 149 μm and 306 μm of applied values, respectively. Assuming that deviation from linearity is accounted for in making measurement, much higher precision is achievable and the standard deviations for these measurements are 0.6 K, 28.5 μm and 56.0 μm, respectively. © 2004 IOP Publishing Ltd.

Third-order intermodulation products generated on transmission through nonlinear radio-on-fibre link

Two-tone intermodulation tests were simulated for an amplitude modulated radio-on-fibre link including fibre dispersion, nonlinearity and loss. The third-order intercept results are presented for varying fibre lengths and optical transmission powers.

3D reconstruction of the complex dielectric function of glass during femtosecond laser micro-fabrication

We report on a new technique to reconstruct the 3D dielectric function change in transparent dielectric materials and the application of the technique for on-line monitoring of refractive index modification in BK7 glass during direct femtosecond laser microfabrication. The complex optical field scattered from the modified region is measured using two-beam, single-shot interferogram and the distribution of the modified refractive index is reconstructed by numerically solving the inverse scattering problem in Born approximation. The optical configuration suggested is further development of digital holographic microscopy. It takes advantage of high spatial resolution and almost the same optical paths for both interfering beams, and allows ultrafast time resolution. © Springer Science+Business Media, LLC. 2011.