DETDET

Present status of

LAPP – 10 / 03 / 2010

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Previous photodiodes

● Virgo set of photodiodes • Hammamatsu

• InGaAs

• Ø = 3mm

• η > 95 % typ.

• Idark <10 nA @ Vbias = 10 V

• Brkdown volt. = 50 V

• Imax ~ 100 mA

• fc ~ 70 MHz– Rs ~ 8 – 10 Ω

– Cs < 280 pF @ Vbias = 10 V

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Advanced requirements

● Increase of the modulation frequency• fmax ~ 2 x 70 Mhz

● Increase of incident power • Photodiodes should handle ~ 200 mW

● Resulting requirements for AdV photodiodes• Basically the same as for Virgo

• Plus :– lower Cs (with the same Ø)

– Increase Imax

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Review of current photodiodes

● Exhaustive review of commercial solutions• 8 manufacturers

– Hammamatsu, Perkin Elmer, Roithner, Fermionics, GPD, eGtran, EOS, Judson

• No major tech improvements for 10 yrs

• Pre selection :– Only 3 remaining manufacturers from which we bought samples

Perkin Elmer (x 5) Fermionics (x 3) Judson (x 2)

• Those samples are under characterization– use of Virgo preamp.

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I Dark

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Equivalent electrical scheme

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● LCR meter

● Perkin Elmer● fc ~ 93 MHz

● Fermionics● fc ~ 41 MHz

● Judson● fc ~ 468 MHz

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DC Linerarity measurements

● Measurement are made by varying the source intensity• beam splitter• the emitted power is measured using a powermeter

● At present• met some difficulties to obtain a reliable absolute measurement

– comparison of several pwm are out of the +/- 4% measurement accuracy

• no coating

● First estimation of η• Perkin Elmer ~ 80 %• Fermionics ~ 60 %• Judson ~ 40 %

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Frequency response

● We investigate several way of modulating the intensity beam on a wide range of frequency (typ 1- 100 MHz)• AOM (fiber or not)

– high frequency limited

• pockels cells– difficulties to reach good modulation index on the whole frequency

range

● Commercial solution from photline• fiber EOM

• from 100 kHz up to 250 MHz

• delivered within 5 weeks

• output power limited to some 10mW

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PE0794

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PE0795

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PE0796

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PE0797

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PE0798

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F1

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F2

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F3

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J1

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J2

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Commandes passées

● Perkin Elmer

• 5 photodiodes – 1950 € HT

• Commandées le 03/11/09

• Livraison : 8 à 14 semaines

● Fermionics

• 3 photodiodes – 802 € HT

• Commandées le 05/11/09

• Livraison : 1 à 2 semaines

● Judson

• 2 photodiodes – 1861 € HT

• Commandées le 12/11/09

• Livraison : 2 à 4 semaines

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