The LEDGON is a benchtop goniometer for determining the angle-resolved spatial radiation properties of laser diodes. The VTC series of camera systems enable extensive characterization of the beam profile in the near- and far field, together with polarization properties. The pulsed VCSEL tester (PVT) is recommended for measurements in the nanosecond range. Major differences between the continuous and pulsed L/I curve are indicative of a poor die attachment or leakage current, and thus lower laser quality. SpecWin Pro supports the connection of an external temperature unit for tests from 15 to 150 degrees Centigrade.įor some applications, a pulsed operating mode of the VCSEL arrays is necessary. A temperature-dependent analysis is thus relevant for certain applications, e.g. The efficiency of laser diodes often declines significantly with rising temperature. Depending on laser type and requirement, further measurement technology is required. With increasing operating current, for a VCSEL this may mean a shift in the peak wavelength to higher wavelengths (see illustration). These sizes often demonstrate a dependence on operating current. In combination with a spectroradiometer, additional spectral properties of the laser diodes such as peak wavelength and FWHM half-band widths can be determined. LIV test systems usually consist of photodiodes, integrating spheres and source-measure-units (SMUs). If we use this to calculate the derivative functions, anomalies (kinks) in the laser diodes become easily recognizable. The V/I curve shows the voltage applied to the laser as a function of the operating current. The L/I curve shows the dependence of optical light intensity of the laser on the operating current and serves to determine the operating point and threshold current.

It combines two measurement curves in one graphic. The LIV test is a fast and simple method of determining the key performance parameters of laser diodes. The software application SpecWin Pro supports the characterization of laser diodes by integrating and precisely synchronizing all measuring instruments, as well as numerical and graphical analysis of the data. Laser diodes can be optically characterized in detail with the appropriate LIV test equipment – additionally consisting of integrating spheres, photodiodes, source-measure-units (SMUs) and temperature controllers.

Du skylder et liv by Steen Lassen