Waveguide loss measurement- endfire coupling

In summary, the conversation discusses an experiment investigating the propagation loss in nanophotonics structures using a tapered lensed fiber and a photodetector. The chip is designed for telecommunication purposes at a wavelength of 1550nm. However, the obtained spectrum shows the Fabry-Perot effect, causing confusion on how to calculate the path from the spectrum. The person asks for clarification on some details, such as the wavelength of the laser and the purpose of measuring spectral losses instead of total average power.
  • #1
maxclark153
8
0
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 wavelenght 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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  • #2
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?
 
  • #3


Hello, thank you for sharing your experiment and results with us. From your description, it seems like you are investigating the propagation loss in nanophotonics structures using a laser light source at a wavelength of 1550nm. Your setup involves coupling the light into the input of the device under test (DUT) using a tapered lensed fiber and then measuring the output using an objective and photodetector.

I understand that you have encountered some issues with your experiment, specifically with the Fabry-Perot effect in your spectrum scan. This effect is caused by multiple reflections between the input and output facets of the device, resulting in oscillations in the spectrum. This can make it difficult to accurately calculate the path length of the light within the device.

In order to address this issue, I would suggest trying to minimize the reflections at the facet interfaces by using anti-reflection coatings or angled facets. Additionally, you may want to consider using a different measurement technique, such as time-domain measurements, to avoid the Fabry-Perot effects.

I hope this helps and good luck with your experiment!
 

What is waveguide loss measurement?

Waveguide loss measurement is the process of quantifying the amount of power lost as a signal travels through a waveguide. This is an important measurement in the field of microwave and RF engineering, as it helps determine the efficiency of a system and can identify any potential issues or flaws.

What is endfire coupling in waveguides?

Endfire coupling is a method of coupling a signal into a waveguide by placing the source directly at the end of the waveguide. This results in a more direct and efficient transfer of energy compared to other coupling methods.

What factors affect waveguide loss in endfire coupling?

The main factors that affect waveguide loss in endfire coupling are the length and material of the waveguide, the frequency of the signal, and any imperfections or misalignments in the coupling process. Other environmental factors such as temperature and humidity can also play a role in loss measurement.

How is waveguide loss measured in endfire coupling?

Waveguide loss can be measured using specialized equipment such as a vector network analyzer, which can measure the amount of power lost in the waveguide by comparing the input and output signals. This measurement is typically expressed in decibels (dB) and can be used to calculate the overall system efficiency.

Why is waveguide loss measurement important in endfire coupling?

Accurate waveguide loss measurement is crucial in endfire coupling as it helps engineers understand the performance of a system and identify any potential issues that may need to be addressed. It also allows for optimization and improvement of the system's efficiency, making it an important aspect of microwave and RF engineering.

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