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Description
In this work, we present a customized pn depletion type Mach-Zehnder modulator (MZM) as well as a fully integrated wavelength division multiplexing (WDM) transmitter design with the merits of high bandwidth and radiation hardness, aiming to upgrade the optical data transmission of future detector systems. A detailed characterization of the modulators on modulation efficiency and RF response was carried out. Based on this work, the first optical link with a data rate of 11.3 Gb/s was set up transmitting 6x10
Summary
The number of detector read-out channels as well as the data rate of each individual channel are rapidly increasing in detector instrumentation. Optical links exploited in current large-scale detector systems use directly modulated laser diode based transmitter units. In this scheme, each transmitter is connected by an individual optical fiber with an off-detector receiver. The most viable way to cope with ever increasing data throughput is adding more and more fibers at the price of increased mass and space requirements. In contrast we propose an integrated WDM transmission system with which the data transmission bandwidth of each fiber can be greatly enhanced. The system also addresses the problem of limited radiation hardness of the laser diodes as they will be placed outside of the radiation area.
According to the radiation hardness study of CERN [1], we fabricated radiation-hardened MZMs with customized etch depth and doping concentration. From steady state measurements, we found the driving voltage on one 3 mm long arm to get a phase shift of
Considering the DC measurement results, RF measurements were carried out by applying a reverse bias voltage of 2.5 V and an RF amplitude of 2
Furthermore a complete transmission experiment was set up based on an FPGA as high-speed data source, a two-stage amplifier to drive the modulator with an amplitude of up to 7
[1] M. Zeiler, S. Seif El Nasr-Storey, S. Detraz, A. Kraxner, L. Olantera, C. Scarcella, Ch. Sigaud, C. Soos, J. Troska, F. Vasey, “Radiation Damage in Silicon PhotonicMach–Zehnder Modulators and Photodiodes”, IEEE Trans. on Nuclear Science, vol. 64, no. 11, Nov. 2017, pp. 2794