LIght Detection And Ranging (LIDAR)

A typical LIDAR setups are based on Time of Flight (TOF) measurement where high power optical pulses (duration in order of nanoseconds) are bounced from objects in the environment. Accurate measurement of the time the pulses take to return to the sensor after reflection are computed to draw a 3D map of the surroundings.
As an example, below is a principle diagram for a MOPFA Lidar (Master Oscillator Power Fiber Amplifier) for wind monitoring application.

^{Fig. 2:  Coherently combined pulsed amplifier setup. Output O1 carrries the total power of outputs A1 and A2}

The Lidar performance depends strongly on the pulse characteristics: high energy pulses and beam quality (for longer reach), high repetition rate (for faster acquisition), narrow linewidth (for higher measurement resolution).
Unfortunately all the above characteritics are contributing to lower the threashold power level at which Stimulated Brillouin Scattering (SBS) becomes a limiting factor. Even at “eye safe” wavelengths, power densities in the core of the fiber prevent pulse peak power.
The solution: A highly doped, Large Mode Area (LMA), low NA, Polarisation Maintaining fiber with a pump guide to harness the power of high-power laser diode.
iXblue IXF-2CF-EY-PM-30-300 combines all the characteritics above enabling high power operation. SBS threasholds are reached only at very high power thanks to the large single mode area reducing the power density. The high absorption allows for short gain fiber length pushing further the SBS power threshold. The low NA allows for a good beam quality.
Actual detailed results can be seen in the following paper:

Three-Dimensional Wind Measurements with the Fibered Airborne Coherent Doppler Wind Lidar LIVE

Results with a 2m length of IXF-2CF-EY-PM-30-300 and 16 Watt of launched power:

• M²= 1,1
• 715 ns pulses with 14 kHz repetition ferquency, pulse energy of 410 μJ

Such a set up allowed windspeed measurement reach up to 16km.