Due to small refractive change, it is difficult to obtain high confined glass integrated waveguide. A proposed solution is to make firstly a planar waveguide by ion exchanged and then to use an optical grade dicing to realize two separated grooves. The cutting and the polishing of the glass are made at the same time. Monomode ridge waveguide with a smallest width of 4 μm and a height of tens micrometers are characterized, either in the near-infrared domain or in the visible domain. The propagation losses can be smaller than 1 dB/cm with fiber coupling losses around 2 dB depending on the fiber used to excite the waveguide.
Proc. SPIE. 7268, Smart Structures, Devices, and Systems IV
KEYWORDS: Electronics, Microsystems, Signal processing, Structural health monitoring, Smart structures, Thermoelectric materials, Chemical elements, Aircraft structures, Instrument modeling, Current controlled current source
Vibration harvesting has been intensively developed recently and systems have been simulated and realized, but real-life situations (including aircraft Structure Health Monitoring (SHM)involve uneven, low amplitude, low frequency vibrations. In such an unfavorable case, it is very likely that no power can be harvested for a long time. To overcome this, multi-source harvesting is a relevant solution, and in our application both solar and thermal gradient sources are available. We propose in this paper a complete Microsystem including a piezoelectric vibration harvesting module, thermoelectric conversion module, signal processing electronics and supercapacitor. A model is proposed for these elements and a VHDL-AMS simulation of the whole system is presented, showing that the vibration harvesting device alone cannot supply properly a SHM wireless node. Its role is nevertheless important since it is a more reliable source than thermoelectric (which depends on climatic conditions). Moreover, synergies between vibration harvesting and thermoelectric scavenging circuits are presented.