Advanced receiver technology for commercial threat warning systems
Advanced threat warning technology will begin to play a more significant role for Homeland defense and National security. Of particular concern are landing and take-off patterns of slow moving commercial airliners here and abroad. Recognizing this vulnerability has triggered renewed interest in high sensitivity internal gain optical detectors and 2D arrays. Avalanche photo detectors (APD’s) are the most highly sought after low-noise, high-gain photo sensors. They are being developed for highly sensitive LADAR receiver systems in autonomous munitions and for data communications (for example) and will be the “eyes” of modern commercial threat warning systems. This paper reviews several LADAR technologies and the corresponding requirements placed on APD’s. Performance of commercial and experimental APD’s will be discussed. Recent results on large format InAlAs APD arrays fabricated by the authors will also be presented.
Monte Carlo simulations of the bandwidth of InAlAs avalanche photodiodes
We present a Monte Carlo simulation of the bandwidth of an InAlAs avalanche photodiode with an undepleted absorber. The carrier velocities are simulated in the charge layer and the multiplication region. It is shown that the velocity overshoot effect is not as significant as simpler models have suggested. At high electric field intensity, the electron effective saturation velocity is only slightly higher when impact ionization is significant, compared with when impact ionization is absent. The simulated 3 dB bandwidth is consistent with experiments for gains up to 50.
Pedagogy of the “Not”: Negation, Exodus, and Postdigital Temporal Regimes
Postdigital capitalist time is an incessant acceleration that acts to homogenize time and wed us to the present, to which we have to constantly catch up. While the impulse of this is no doubt economic (the realization of value), it is crucially undergirded by a pedagogical logic wherein we have to perpetually learn and re-learn the latest apps, social media configurations, operating systems, and so on. Political strategies of resistance thus need to be bolstered by an alternative mode of educational life, and I propose a pedagogy of the “not” as one possibility. Such a pedagogy is an act of suspension that sustains a detachment from the present, clearing out oppositions and thereby exposing us to a radical indeterminacy and potentiality that is always untimely. Suspension is the praxis of negation, which means that negation operates by keeping sense indeterminate to meaning and signification. Rather than suppressing, disavowing, or annihilating the stated content, negation retains even that which is negated. While this would appear as a form of exopedagogy, which withdraws from the dialectic of the private/public, I instead argue that it redefines the terms of any dialectic, redefining the very categories exopedagogy withdraws from. Before concluding, I spend some time with Sandy Grande’s important critiques of Eurocentrism and progress in Western critical education, demonstrating how negation as suspension circumvents these errors through its accommodation of—or, better, insistence on—variegated temporalities and forms of life.