In this paper, we introduce an innovative proposal for a low cost micro Raman spectrometer for non-invasive glucose monitoring. In this design, an Array Waveguide Grating (AWG) chip integrated with PIN photodiodes and a prism coupling are proposed to replace fiber micro alignment in packaging and to reduce system cost. Experiments were designed and conducted to evaluate the impact of thickness of the waveguides and the incident angle of the laser beam on the efficiency of the prism coupling. Considerable light coupling was observed when the waveguide core is 2mm thick. An updated fabrication process was designed and test chip was also fabricated to determine the critical feature size to solve the problem of air bubble resulted in trench filling.
The standard Findlay Clay Analysis cannot be applied to diode side-pumped Nd:YAG lasers because both the pump wavelength as well as the gain change with the diode current and the cooling water temperature. We have developed a modified method which is based on the variation of the cooling water temperature to determine the lowest threshold for each output coupler. We have applied this technique to a 300 Watt class side Nd:YAG rod laser. The resulting Findlay Clay plot exhibits very good linearity and the measured gain and loss were confirmed by comparing measured output power at different cooling water temperatures with theoretical values provided by a Rigrod power model.