Waveguide loss measurement- endfire coupling

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SUMMARY

The discussion focuses on measuring propagation loss in nanophotonic structures designed for telecommunications, specifically at a wavelength of 1550nm. The experiment utilizes a tapered lensed fiber for input coupling and an objective lens for output detection via a photodetector. The observed spectrum exhibits Fabry-Pérot oscillations, complicating the loss measurement due to mismatched dimensions between the fiber-chip facet and the chip's end facets. Participants emphasize the importance of using a 1550nm laser source for accurate total average power measurements instead of spectral loss calculations.

PREREQUISITES
  • Understanding of nanophotonics and waveguide structures
  • Familiarity with optical measurement techniques, specifically using photodetectors
  • Knowledge of Fabry-Pérot effects in optical systems
  • Experience with fiber optics, particularly tapered lensed fibers
NEXT STEPS
  • Research techniques for mitigating Fabry-Pérot effects in optical measurements
  • Learn about the design and optimization of tapered lensed fibers for improved coupling
  • Investigate methods for accurate propagation loss measurement in nanophotonic devices
  • Explore the use of broadband laser sources in telecommunications applications
USEFUL FOR

Researchers and engineers in the field of nanophotonics, optical engineers, and telecommunications professionals focused on waveguide design and performance optimization.

maxclark153
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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 _?
 
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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?