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Entry  Mon Jul 21 10:30:38 2014, Harry, Update, General, Fiber Mode Measurement fiberModeMeasurement.pngfiberModeFit2.pngfiberModeMeasurement2.zip
    Reply  Mon Jul 21 18:08:19 2014, Harry, Update, General, Fiber Mode Measurement fiberModeMeasurement3.png
    Reply  Tue Jul 22 16:26:04 2014, Harry, Update, General, Fiber Mode Measurement fiberModeProfile3.pngfiberModeMeasurement4.zip
Message ID: 10244     Entry time: Mon Jul 21 10:30:38 2014     Reply to this: 10249   10255
Author: Harry 
Type: Update 
Category: General 
Subject: Fiber Mode Measurement 

 Purpose

The idea was to measure the profile of the light coming out of the fiber, so we could have knowledge of it for further design of measurement apparatuses, for characterization of the fibers' properties.

Methods

The method was the same as the last time I tried to measure the fiber mode.

This time I moved the beam profiler in a wider range along the z-axis.

Additionally, I adjusted the coupling until it gave ~1mW through the fiber, so the signal was high enough to be reliably detectable.

Measurements were taken in both X and Y transections of the beam.

The range of movement was limited by the aperture of the beam profiler, which cuts off at 9mm. My measurements stop at 8.3mm, as the next possible measurement was beyond the beam profiler's range.

fiberModeMeasurement.png

Analysis

I entered my data into A La Mode, which gave me a waist of 5um, at a location of z = -0.0071 m, that is to say, 7.1mm inside the fiber.

Note that in the plot, data points and fits overlap, and so are sometimes hard to distinguish from each other.

Code is attached.

fiberModeFit2.png

Moving Forward

Using this data, I will begin designing setups to measure fiber characteristics, the first of which being Polarization Extinction Ratio.

Eventually, the data collected from these measurements will be put to use in the frequency offset locking setup.

Attachment 3: fiberModeMeasurement2.zip  43 kB  Uploaded Mon Jul 21 11:35:58 2014
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