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Message ID: 10240     Entry time: Sat Jul 19 01:59:34 2014
Author: Harry 
Type: Update 
Category: General 
Subject: Fiber Mode Measurement 

Purpose 

We wanted to measure the mode coming out of the fibers, so we can later couple it to experimental setups for measuring different noise sources within the fiber. i.e. Polarization Extinction Ratio, Frequency Noise, Temperature Effects.

Methods

I used the beamscan mounted on a micrometer stage in order to measure the spot sizes of the fiber coupled light at different points along the optical axis, in much the same way as in the razorblade setup I used earlier in the summer.

fiberModeMeasurement.png

Analysis

I entered my data (z coordinates, spot size in x, spot size in y) into a la mode to obtain the beam  profile (waist size, location)

 fiberModeMeasurement1.png 

Code is attached in .zip file.

Moving Forward

After I took these measurements, Manasa pointed out that I need points over a longer distance. (These were taken over the range of the micrometer stage, which is 0.5 inches.)

I will be coming in to the 40m early on Monday to make these measurements, since precious beamscan time is so elusive.

Eventually, we will use this measurement to design optical setups to characterize Polarization Extinction Ratio, Frequency Noise, and temperature effects of the fibers, for further use in FOL.

Attachment 3: fiberModeMeasurement1.zip  44 kB
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