Speaker
Description
Summary
Keywords: Laser, VCSEL, model, Verilog-A, transceiver, radiation hard.
SUMMARY
The versatile transceiver under development for the Super Large Hadron Collider (SLHC) experiment will have to endure severe radiation conditions while providing multiple gigabit per second data transmission capability to cover the experiments requirements [1, 2]. For this, characterization and modeling of the electro-optic components (in particular the semiconductor laser), are of upmost importance as they will enable the correct design and optimization of the transceiver [3]. They will also enable to evaluate the link performance when the physical characteristics of the device change due to the environmental circumstances.
A measurement methodology will be presented whose results lead to the implementation of a model with broad validity. This model accommodates several different laser types (Fabry-Perot, Distributed Feedback, Vertical Emission) [4-7]. The laser model is implemented in Verilog-A for ease of use by integrated circuit designers, and it aims at easing the design of robust systems capable of complying with the demanding requirements of high energy physics experiments.
Since the impedance mismatch between the driver and the laser should be kept as low as possible to decrease inter-symbol interference, jitter and power loss, a very accurate model of the laser chip input and parasitic network was developed. It will be shown that the theoretical model is in good agreement with experimental data and that it enables correct design of the transmitter circuitry of the laser driver. The results of the study of an impedance matching network and signal pre-emphasis will be shown.
Current work is focusing on the use of the model to predict the performance degradation with environmental conditions and analyses of the system sensitivity to manufacturing parameter deviations [8].
REFERENCES
[1] Hessey, N. (2008), “Overview and Electronics Needs of ATLAS and CMS High Luminosity Upgrades”, Proceeding of the TWEPP2008, Naxos, Greece.
[2] Amaral, L. et al (2008), “Evalutation of Multi-Gbps Optical Transceivers for Use in Future HEP Experiments”, Proceeding of the TWEPP2008, Naxos, Greece.
[3] Tucker, R.; Kaminow, I., "High-frequency characteristics of directly modulated InGaAsP ridge waveguide and buried heterostructure lasers", Journal of Lightwave Technology, vol.2, no.4, pp. 385-393, Aug 1984.
[4] Morton, P. A.; et. al, “Frequency response subtraction for simple measurement of intrinsic laser dynamic properties,” IEEE Photon. Technol. Lett., vol. 4, pp. 133–136, Feb. 1992.
[5] Salgado, H. M.; and O’Reilly, J. J.; “Volterra series analysis of distortion in semiconductor laser diodes,” Proc. Inst. Elect. Eng. J., vol. 138, no. 6, pp. 379–382, Dec. 1991.
[6] Cartledge, J.C.; Srinivasan, R.C. (1997), "Extraction of DFB laser rate equation parameters for system simulation purposes", Journal of Lightwave Technology, vol.15, no.5, pp.852-860.
[7] Bruensteiner, M.; Papen, G.C. (1999), "Extraction of VCSEL rate-equation parameters for low-bias system simulation," IEEE Journal of Selected Topics in Quantum Electronics, vol.5, no.3, pp.487-494.
[8] Blokhin, S. A. et al (2006), “Experimental Study of Temperature Dependence of Threshold Characteristics in Semiconductor VCSELs Based on Submonolayer InGaAs QDs”, Journal of Semiconductors, Vol. 40, pp1232-1236.
