NanoTest VCSEL measures VCSEL on wafer level or Chip on Carrier regarding their optical and electrical characteristics. The tester accommodates wafers with a diameter of up to 6 inches (150 mm), as an option also larger diameters can be integrated. A special interface mounted to the chuck also allows for testing Chip on Carrier devices.
A high-precision motion system with XYZ and rotary adjustment brings the wafer chuck in the respective measurement position. First, electrical contacting takes place supported by a sideview camera. A high-precision current source delivers the operating current for the VCSEL under test.
The central camera above the wafer chuck utilizes automated machine vision for the correct positioning of the respective VCSEL. A multimode fiber with 50 µm core diameter collects the emitted optical radiation and brings it to the measurement channel for optical power measurement.
The recording of the LVI curve is the basic routine which determines the quality of the VCSEL. An optical spectrum analyzer measures the spectral characteristics. With a network analyzer, the modulation behavior of the VCSEL can be calculated. Last but not least the relative intensity noise (RIN) can be evaluated.
In order to take measurements at various temperature, the chuck can be adjusted between -10° C and 100° C.
The software package TestMaster monitors all functions of the test station and schedules the measurement procedures. A local database stores the values which are available for further analysis. The local calculation of the data and the quality assessment can be shown as a color map. In this way, the usable zones on the wafer can be easily found.
In the standard configuration, TestMaster offers already a series of interfaces for the integration of external instrumentation, such as optical spectrum analyzers, source meters and network analyzers.
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