Yuting Huang,1 Yu Yao,1 Kais Al-Naimee, 1,2 and Claire
Gmachl1
1 – Department of Electrical Engineering and MIRTHE,
Princeton University, Princeton, NJ 08544 USA, and NSF-ERC,
USA
2 – Permanent address : National Institute of Applied Optics,
Phys. Dep., University of Florence, Florence, Italy
Why Investigate
Light Instability?

Power Instability has long been a known problem in traditional lasers but not in high
profile QC lasers. 1

Finding potential quasi-period behaviors of light instability can help make much more
powerful lasers by stabilizing them on the higher power state.

.
Fig 1. Zooming in on 7 sequential
light pulses out of 5000 pulses in P2 Laser3.
Fig 2 shows
around 100 light
pulses at I = 0.7
A, the current for
stable light
output.
Fig 3 shows around
160 light pulses at I =
2.4 A, the current for
extremely unstable
light output.
1. K.J. Franz, J.J.J. Raftery, P.Q. Liu, A.J. Hoffman, M.D. Escarra, S.S. Howard, Y. Dikmelik, J.B. Khurgin, X. Wang, J.-Y. Fan, C. Gmachl "Negative Differential Resistance and Pulse Instabilities in Minimalized Quantum Cascade
Laser Structures," Conference on Lasers and Electro-Optics (CLEO), Baltimore, MD, June 2009..
• (The figure above) Easy-to-use Matlab
interface monitors up to 5,000
sequential pulses
• plots light output instability in the
gate regions.
• In the right figure a laser holder is shown. The laser is opposite
to a light detector, a voltage generator, an oscilloscope and the
computer.
•
We choose the region of instability on
each pulse as the gate region.
• (In the above figure) Gate region is
between the red lines.
• (In the right figure) Data calculated by averaging the light power output in
the gate region on each pulse may reveal the light instability pattern hidden
in QC laser.
Conclusion
We succeeded in developing a real time, pulse by pulse measurement
system that allows monitoring laser dynamics and chaos.