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Light Detection And Ranging
LIDAR
Exail can deliver a wide range of optical components for the design of high-power laser sources (in pulsed regime) for lidar applications: windmills for wind speed measurements, autonomous vehicles for the mapping of their environment, and even lidars in space.
Lithium niobate (LiNbO
3) phase and intensity modulators and the latest generation of Er/Yb doped fibers are particularly optimized to enable higher efficiency with lidar laser sources. On the detection side, Exail customized micro-optical benches can be useful whether the lidar systems rely on “time-of-flight” measurement with scan capability (distance measurement) or is dedicated to measure wind speed.
Typical LIDAR SETUPS are based ON TIME OF FLIGHT (TOF) MEASUREMENT
The generic term of LIDAR for LIght Detection And Ranging finds its use nowadays in many different systems and applications. Applications range from the scanning of surroundings to create a 3-D digital map of obstacles (for instance in autonomous driving applications) to atmospheric Lidars that detect gases or aerosol particules (for instance in environmental applications). Another well spread application is the detection of atmospheric turbulences to secure wind-turbines operation or airports.
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.
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.
Exail
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:
https://www.mdpi.com/2073-4433/10/9/549
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 frequency, pulse energy of 410 μJ
- Such a set up allowed windspeed measurement reach up to 16km.
Dedicated Products
 |  |
|---|---|
Core Diameter | Core Diameter |
Cladding Diameter
| 300 µm |
NA | 0.09 |
Clad Absorption | >2.8 dB/m @915nm |
Clad Absorption | >11.0dB/m @976nm |
Clad Absorption | >70 dB/m @1536nm |
Matching passive fibers
- PM large core single clad fiber > IXF-PAS-PM-30-300-0.08_edA Preliminary
- PM large core single clad fiber > IXF-2CF-PAS-PM-30-300-0.08_edA double clad passive pm fiber
Other references of optical fibers
Er/Yb Doped Fibers | ||
|---|---|---|
12 µm core diameter | 55 dB/m absorption at 1536 nm | |
12 µm core diameter | 70 dB/m absorption at 1536 nm | |
12 µm core diameter | 65 dB/m absorption at 1536 nm | |
25 µm core diameter | ||
30 µm core diameter | ||
5 µm core diameter | All Glass High Temperature Coating | |
8.5 µm core diameter | All Glass High Temperature Coating | |
12 µm core diameter | All Glass High Temperature Coating | |
Er/Yb Doped Fibers | ||
C & L Band | 18 dB/m absorption at 1530 nm | |
C & L Band | 24 dB/m absorption at 1530 nm | |
C & L Band | 30 dB/m absorption at 1530 nm | |
Latest Er/Yb Doped Fibers | ||
10 µm core diameter
| High Power Amplifier | |
13 µm core diameter
| High Power Amplifier | |
Lithium Niobate (LiNbO3) phase & intensity modulators
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