Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum.
Progress rept. no. 36, 1 Oct 85-30 Sep 86,
COLUMBIA RADIATION LAB NEW YORK
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New developments have been achieved in the quantum generation and detection of light. The usual semiclassical theory of light detection turns out to be incomplete. The theory has been extended to include the possibility of feedback from the detector to the source which changes the theory substantially. In the revised theory the noise at the output of a detector can be below shot noise even though the incident light is classical, i.e., above shot noise. However, the action of such an electron current configured in an external feedback loop can be useful for converting Poisson light into amplitude-squeezed sub-Poisson light. A configuration making use of transitions between the energy levels of a quantum-well heterostructure has been developed. The noise properties of superlattice avalanche photodiodes SAPDs have been compared with those of conventional avalanche photodiodes CAPDs for the detection of both amplitude-squeezed light and conventional light. SAPDs are heterostructure devices constructed in such a way that principally one kind of carrier impact-ionizes. Performance and time response have been evaluated for lightware communication systems. These detectors exhibit promising characteristics.
- Optical Detection and Detectors
- Radiofrequency Wave Propagation