Extrinsic Active Waveguides and IWAOs

System B is based on the deposition of a specific 4-p,m-thick polymeric active waveguide over a micromachined silicon circuit of curved ARROW waveguides. 

The optical source is a diode laser and fiber-emitter and fiber-detector coupling is accomplished using standard optical fiber connectors. The detector is a PIN photodiode connected to a transimpedance preamplifier and the signal is amplified and filtered using a lock-in amplifier that also tunes the modulation frequency of the laser source. The analytical signal is collected and treated by a PC. 

The latter system has been called an IWAO and the results obtained have demonstrated its suitability to be employed as a sensing platform, which confers versatility, robustness and mass-production capabilities besides high sensitivity on conventional bulk optodes. For these reasons it is going to be described in more detail next. 

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