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B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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LED based powerful nanosecond light sources for calibration systems of
deep underwater neutrino telescopes
B.K.LubsandorzhievInstitute for Nuclear Research
Moscow RussiaUniversity of Tuebingen
Tuebingen Germany
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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Ultra Bright Blue LEDs
S.Nakamura NICHIA 1993
Single quantum well InGaN/GaN structure
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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0 5 10 15 20 25 30 35
0,01
0,1
1
Time, ns
W, a.u.
0 5 10 15 20 25 30 35 40 45
0,01
0,1
1
W, a.u.
Time, ns0 10 20 30 40 50 60 70 80 90 100 110
0,01
0,1
1
W, a.u.
Time, ns
0 10 20 30 40 50 60 70 80 90 100 110
0,01
0,1
1
W, a.u.
Time, ns
Ultra bright LEDs emission kinetics
Fast LEDs(Nichia «old», G-nor, YolDal) Intermediate LEDs
Slow LEDs Nichia «old» and «new» LEDs
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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NSPB500S NICHIA CHEMICAL KINGBRIGHT L7133NBCslow L7113PBC
«old» - 1.8 ns width«new» - 4ns width τ~10ns
«old» - 1.8 ns width«old» - 4.5 ns width τ~16ns
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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G-nor GNL3014BC
The fastest LED0.6 ns width!Without tail!
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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• Drivers with single LEDs provide 1 ns width (FWHM) light pulses with up to 109 photons per pulse.
• How to increase light yield keeping emission kinetics fast?
• To assemble LEDs in a matrix.• Problems: Light emission kinetics of the whole matrix?• LEDs in the matrix should be selected thoroughly.• They should be identical in their emission kinetics and
intensity• If several drivers - they should electronically tuned
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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LED Matrix. One driver for a Matrix of LEDs
Nearly identical (in emission kinetics, spectrum and light intensity) LEDsare selected for the matrix. The light pulses of individual LEDs coincidewith each other with an accuracy of ≤50 ps.
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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Matrix of LED drivers
Each LED of the matrix has its own driver based on avalanche transistor. LEDs and their drivers are thoroughly tuned to be identical in timing and intensity. The light pulses of individual drivers coincide with each other with an accuracy of ≤50 ps.
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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LED stability and life time
109 10100,9
1,0
1,1
?enei eiioeunia
Naaoiauoia, ioi. aa.
(a)
109 10101,5
2,0
2,5
Длительность импульса tFWHM, нс
?enei eiioeunia
(a)
Pulse width (left, ns) and light yield (right, a.u) vs
the total number of pulses
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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Driver’s parameters temperature dependences
-10 0 10 20 30 40 500,9
1,0
1,1Naaoiauoia, ioi.aa.
Oaiia?aoo?a, 0C
(a)
-10 0 10 20 30 40 501,5
2,0
2,5
Длительность импульса tFWHM, нс
Oaiia?aoo?a, 0N
(a)
Pulse width (left, ns) and light yield (right, a.u)vs
temperature
Temperature coeff. - 0.14%/C in the range of -3 ÷ 45 C
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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Cluster of n matrixes of ultra bright blue LEDs
light pulses with ≥1011 photons per pulse with 1-2 ns width
B.K. Lubsandorzhiev VLVnT08 Toulon 24 April 2008
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High power LEDs
1011 -1012 photons per pulse6-10 ns width
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• Ultra bright blue LEDs give excellent opportunities to design powerful, fast light sources for calibration systems of astroparticle physics experiments based on Cherenkov and scintillation techniques
• Using matrixes of ultra bright blue LEDs it’s possible to have light sources with 1-2 ns width (FWHM) and intensity of up to 1010 photons per pulse and even more, and with a cluster of matrixes - 1011 photons per pulse.
CONCLUSION
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• New ultra high power blue LEDs allow to have light sources intensity of ≥1012 photons per pulse with a single LED but their emission kinetics relatively slow - ~5-10 ns (FWHM).
• Powerful light sources based on ultra bright blue LEDs have very high long-term stability abd very long life time.
• They are powerful, fast, stable, reliable, cheap and very simple in operation.
• They are in many respects very good competitor to laser systems.