Fast Univeral Tunable Optical Filter – FASTUNE

The design is carried out using the following design / modeling means: - Optical calculations on ZEMAX - Mechanical CAD on SOLIDWORKS - Electronic simulations on LTSPICE, ADISIMPE, TINA - Electronic CAD on ALTIUM DESIGNER The measurement chain is controlled by LABVIEW

Realization and assembly of 3 complete modules: - Optomechanical mount - Fiber coupling optics - Peltier + Radiator effect module - Tunable filter - Connector support - Insulating block Implementation of a characterization bench with SLED (1550nm) and optical spectrum analyzer for characterization of the wavelength filter Implementation of a second bench for temporal characterization

Realization of 3 complete FBG interrogators Here are the steps: - Finalization of electronic circuits for detection, filter control and thermostatisation - Packing - Choice of embedded electronics for interfacing - Realization of an HMI - Tests and characterization

FASTUNE has not yet published An article or a conference will be expected for the last part of the project

In this project, we propose to realize an optical filter based on an innovative and powerful technology. This fibred device use a new tunable interferometric cavity with electrostatic actuation, which can reach wavelength shifts greater than 100 nm and sweeping frequency up to 40 kHz. This component has optical characteristics compatible with many applications such as:

• spectral analyser within interrogator of optical sensors Bragg filter (FBG),
• interferometer for Optical Coherence Tomography (OCT),
• tunable filter for gas Spectroscopic analysis (absorption or Raman), multispectral imaging or for Telecom using the WDM

In this project, we selected the analysis of FBG sensors as the relevant application to demonstrate the potential of such a component. This filter associated with a source of wide spectral band and a circulator "3 ports' allows to analyze the reflected optical signal to the sensors. We propose to improve measurement performance, compactness, and reduce the cost of optical sensing interrogator, due to a new approach based on this kind of tunable filter manufactured using this new technology. The originality of this device comes from the simple and minimalist configuration of the optical system. Thus, compared to the state of the art, this project clearly represents a significant progress in conceptual term for a new design of interrogators and indeed, we expect a high market penetration for this instrument in relation to the existing available, and on numerous market sectors, such as embedded systems.
This measurement system is essential for managers in civil engineering or rail operators, or more generally in the transport, to increase the quality of structures monitoring, user safety and simultaneously reduce the use and maintenance costs associated.
This type of interrogator is therefore based on a spectral analyzer having high performances! In fact, besides the compactness needed for some embedded application and easy handling / address wavelength, the spectral resolution of the interrogator must typically be 1 pm with a sweeping rate of several tens of kHz in specific application. This is due to the fact that only a measurement with occuracy of 1pm ensures a thermal resolution of 1/10 ° C and a resolution of 1 µm/m measurement distortions, commonly values ??targeted by users.
The consortium is composed of a public Engineer school teaching-research institution (telecom Britain) a research center (CEA LIST) and SME (EVOSENS). Telecom Bretagne is responsible for the fabrication and characterization of the filter. Evosens has in charge the mechanical optics and electronics integration of filter in the interrogator. CEA will be responsible for developing the measurement tool and characterization of device with a set of sensors. The aim is to achieve an operational interrogator corresponding to a TRL6 (or TRL7).
The interrogator is designed within the compact tunable filter. We plan to develop a compact packaging, typically in a volume not exceeding 10 × 10 × 10 cm 3, or 1 liter, which is small enough to fit in the palm of the hand, and 3 to 4 times more compact than current competition. This unit will be compact with no moving parts and capable of addressing typically fifty Bragg grating sensors. This type of interrogator is primarily designed to achieve physical measurements, and it can be installed on any any area of land with great energy autonomy.