Exploring the Cut-Back Method: How to Measure Propagation Losses

[nordmoon]

How does the Cut-Back method work experimentally? The Cut-Back Method is a method to determine the propagation losses of fibers or waveguides. I have found tons of articles stating they used this method in comparison but no detailed information on how one can execute it successfully?

Anything you have to consider when executing this method on a optical waveguide?

 

[Claude Bile]

The cut-back method is a way to separate the propagation loss through the waveguide from the coupling losses that occur at the input and output. It is applied by changing the length of the waveguide and observing the change in loss. The propagation loss (in dB/cm) is the change in measured loss (in dB) divided by the change in length in the waveguide (in cm).

The main thing to consider is to keep the coupling losses consistent across both loss measurements; this is relatively straightforward for optical fibres, but can be tricky for other types of waveguides - particularly those that are difficult to cleave, or require polishing or some other post-processing to obtain a clean facet.

Claude.