Two-photon absorption autocorrelation of visible to ultraviolet femtosecond laser pulses using ZnS-based photodetectors

In this letter, we demonstrated an autocorrelator based on two-photon absorption (TPA) of ZnSSe photodetectors, which is capable of measuring femtosecond laser pulses from 800 to 400 nm. This broad bandwidth autocorrelator has high sensitivity and is capable of measuring laser pulses as short as 27...

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Bibliographic Details
Published in:IEEE photonics technology letters 2002-01, Vol.14 (1), p.86-88
Main Authors: Sun, T., Fung, B.K.K., Sou, I.K., Wong, G.K.L., Wong, K.S., Lanzani, G.
Format: Article
Language:English
Subjects:
Autocorrelation
Bandwidth
Detectors
Electromagnetic wave absorption
Energy measurement
Femtosecond
Impurities
Lasers
Optical pulses
Photodetectors
Pulse measurements
Spectra
Ultraviolet
Wavelength measurement
Wavelengths
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Summary:In this letter, we demonstrated an autocorrelator based on two-photon absorption (TPA) of ZnSSe photodetectors, which is capable of measuring femtosecond laser pulses from 800 to 400 nm. This broad bandwidth autocorrelator has high sensitivity and is capable of measuring laser pulses as short as 27 fs and pulse energy of a few picojoules. These results could lead to cost-effective ultrafast autocorrelator with a single detector head to cover the whole visible to near ultraviolet spectral region. Our TPA measurement shows that the defect and impurity states below the bandgap (E/sub g/) have detrimental effect for excitation wavelengths near the bandedge, however, these states are also beneficial by extending the operation wavelengths of the detector beyond E/sub g//2. Using a ZnMgS photodetector with a larger E/sub g/ enables the autocorrelator to be more sensitive at 400 nm, and extends the responsivity further into the ultraviolet wavelengths.
ISSN:1041-1135
1941-0174
DOI:10.1109/68.974170