Waveguide loss measurement- endfire coupling

[maxclark153]

Hi, I am doing an experiment to investigate the propagation loss in some nanophotonics structures.

The laser light is coupled to the input of the DUT chip via a tapered lensed fiber and the output of the chip is go through a objective then a photodetector.

The chip is design for telecommunication propose, so wavelength of interest is around 1550nm.

I did a spectrum scan for 1500 - 1600 nm and obtained the spectrum as below..

http://img134.imageshack.us/img134/7893/clipboard01ww2.th.jpg

Unfortunately , the spectrum is with the fabry perot effect.. (the oscillation), i try to calculated the path from the spectrum , but the calculated dimension doesnot match the fiber-chip facet or both end facet of chip .

So if you gurus outthere can help _?

 

[n0_3sc]

I'm not quite sure what your question is exactly.

There are some things that you should clear up:
- What wavelength laser are you putting into your chip? Is it broadband?
- The fabry-perot effect is arising from the reflections within the chip?
- If the chip is designed for 1550nm, why are you trying to measure spectral losses? Why can't you use a 1550nm source and just measure the total average power at the output?