Aissa Harhira

A ‘living’ prosthetic iris

AimTo design and demonstrate dynamic pupils, which react to light for use with ocular prostheses.MethodsThe realism of ocular prostheses is limited by the immobility of the pupil. Our solution is to use a liquid crystal display (LCD) in the prosthesis to vary the pupil size as a function of the ambient light. Several liquid crystal cells were fabricated and tested for survivability through the ocular prosthesis manufacturing process. The dynamic pupil is controlled by a novel and entirely autonomous, self-powered passive electronic circuit using a solar cell, matching the minimum diameter of the pupil.ResultsThe first LCD surviving the rugged conditions of the ocular prosthesis manufacturing steps and an entirely passive circuit controlling the pupil have been demonstrated for the first time to our knowledge. A design for a complete prosthesis with a dynamic pupil has been proposed. Finally, a standard device for the mass production of ocular prostheses is presented.ConclusionWe have shown that a practical solution for an autonomous self-powered dynamic pupil is possible, given the constraints of size, fabrication process, weight, cost and manufacturability on a mass scale. We envision that the LCD could be mass produced, and only the final steps for the integration of the iris matched to a patient would be necessary before assembly using standard processing steps for the production of the prosthesis. Using a clinical trial, we hope to demonstrate that the dynamic pupil will have a positive impact on the quality of life of patients.

Stimulated Brillouin scattering in multi-mode fiber for sensing applications

We present measurements and characterization of stimulated Brillouin scattering (SBS) in multi-mode fiber (MMF) in comparison with single-mode fiber (SMF). As can be expected, the threshold for SBS was measured to be much higher in MMF (105 mW) compared with SMF (15 mW). A difference of 525 MHz was observed in the SBS frequency shift between both types of fibers. An increase in the gain bandwidth, which was measured to be 17 MHz for MMF compared to 8 MHz in SMF and which is due to several modes present in the MMF. Temperature dependence of the frequency shift was also investigated and was shown to be the same (1 MHz/°C) for both types of fibers. Several applications are therefore proposed using SBS in multi-mode fiber.

High sensitivity inline fiber Mach-Zehnder interferometer bend sensor using a twin core fiber

A novel Mach-Zehnder interferometer based on a multimode fiber combined with a twin-core fiber is proposed. The section of twin-core fiber is spliced between a section of multimode fiber and a single mode fiber. The curvature induced wavelength shifts on the interference fringes is experimentally monitored. A blue shift is observed. This device is simple to fabricate, and is used as a bend sensor with good sensitivity.

An ocular prosthesis which reacts to light

The realism of an ocular prosthesis is limited by the immobility of the pupil. Our method to solve this problem is to use a liquid crystal display (LCD) to control the pupil size as a function of the ambient light. This study demonstrates the first LCD to our knowledge surviving the ocular prosthetic manufacturing steps. The dynamic pupil is controlled by a novel, entirely autonomous and self-powered passive electronic circuit using photodiodes in a high voltage configuration. Future work for a complete prosthesis with a dynamic pupil is discussed. Finally, a standard device for the mass production of ocular prostheses is presented.

Complex optical microcomponents for integrated-optic applications fabricated by laser ablation

Complex concatenated channel waveguides and multimode interference devices have been fabricated by laser ablation of silica-on-silicon substrates for the first time to our knowledge. The technique is based on a tightly focused carbon dioxide laser beam that modifies the refractive index of the area sorrounding the optical waveguide; the process is fast (a few seconds) without any subsequent mechanical or chemical treatment, and the writing speed is about 500 times faster than with UV or femtosecond writing. The results are encouraging for prototyping for the development of an optical sixport device, the equivalent of the widely known microwave technique for amplitude and phase measurements.

A Simple Bend Sensor based on multimode interference and a Twin Core Fiber Mach-Zehnder Interferometer

An optimized Bend Sensor based on a multimode interference combined with a twin-core fiber is proposed. The bend induced wavelength shifts on the interference fringes is experimentally monitored. Losses in multimode fiber are studied.

Optical fiber tissue elasticity sensor

This paper demonstrates a highly sensitive force sensor for bio-medical applications, using a reduced diameter fiber Bragg grating probe in a capillary tube.

LPG on Tapered Fiber Fabricated by Holographic Technique and 10.6µm Radiation

LPG on tapered fiber are fabricated by use 10.6 µm radiation and a phase mask. A laser is incident normally on the phase mask and imprints a thermally induced periodic modulation into the tapered fiber.