Article

An ultraviolet nanosecond light pulse generator using a light emitting diode for test of photodetectors

Review of Scientific Instruments (Impact Factor: 1.58). 02/1997; 68(3):1365-1368. DOI: 10.1063/1.1147943

ABSTRACT An optical function pulse generator that emits (1) short pulse of 1 ns duration, (2) double pulse with variable time interval, and (3) square waveform pulse of variable width in nanosecond range is devised using an InGaN/AlGaN double heterostructure light emitting diode (LED). Although the LED emits a 450 nm (blue) light under conventional dc operation below 30 mA, 380 nm light due to the InGaN/AlGaN component appears when a current larger than 50 mA is applied. This phenomenon is used to realize a pulsed ultraviolet light source. Under large nanosecond current pulsing (peak current >1 A), an intense pulsed emission of 380 nm is obtained. Pulse waveform of the LED emission can be adjusted electrically by applying a shaped current to the LED. To evaluate the potential of the pulse generator as a test source of photodetectors, the response waveforms of photomultiplier tubes were measured. © 1997 American Institute of Physics.

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    • "Figure 3 shows a typical instrumental pulse recorded using an IBH TBX-04 detector under TCSPC conditions at a time calibration of 27 ps per channel, as used for all the time-domain measurements. The ∼600 ps full width at half maximum (fwhm) is significantly faster than previous reports with visible LEDs [3] [4] [5] [6] and compares very favourably with a typical hydrogen flashlamp pulse also shown. Figure 4 shows the emission spectrum of HSA in an alcohol-free hydrated sol–gel matrix of tetramethylorthosilicate (TMOS) prepared at pH 7.5 using standard hydrolysis and condensation reactions [14] and "
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    • "The technical specifications of this LED are: central wavelength = 365nm, full width at half the maximum spectral width (FWHM) = 9nm, maximum operational current (CC) = 700mA, maximum dissipation power = 3.3W [10]. In order to operate the UV LED in the pulsed mode we built a pulse generator for current (PGC) [14]. This generator is externally triggered in a range of 10 to 20 kHz (figure 2.a). "
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