3,508 research outputs found
Unbiased All-Optical Random-Number Generator
The generation of random bits is of enormous importance in modern information
science. Cryptographic security is based on random numbers which require a
physical process for their generation. This is commonly performed by hardware
random number generators. These exhibit often a number of problems, namely
experimental bias, memory in the system, and other technical subtleties, which
reduce the reliability in the entropy estimation. Further, the generated
outcome has to be post-processed to "iron out" such spurious effects. Here, we
present a purely optical randomness generator, based on the bi-stable output of
an optical parametric oscillator. Detector noise plays no role and no further
post-processing is required. Upon entering the bi-stable regime, initially the
resulting output phase depends on vacuum fluctuations. Later, the phase is
rigidly locked and can be well determined versus a pulse train, which is
derived from the pump laser. This delivers an ambiguity-free output, which is
reliably detected and associated with a binary outcome. The resulting random
bit stream resembles a perfect coin toss and passes all relevant randomness
measures. The random nature of the generated binary outcome is furthermore
confirmed by an analysis of resulting conditional entropies.Comment: 10 pages, 4 figure
Modelocked mid-infrared frequency combs in a silicon microresonator
Mid-infrared (mid-IR) frequency combs have broad applications in molecular
spectroscopy and chemical/biological sensing. Recently developed
microresonator-based combs in this wavelength regime could enable portable and
robust devices using a single-frequency pump field. Here, we report the first
demonstration of a modelocked microresonator-based frequency comb in the mid-IR
spanning 2.4 {\mu}m to 4.3 {\mu}m. We observe high pump-to-comb conversion
efficiency, in which 40% of the pump power is converted to the output comb
power. Utilizing an integrated PIN structure allows for tuning the silicon
microresonator and controling modelocking and cavity soliton formation,
simplifying the generation, monitoring and stabilization of mid-IR frequency
combs via free-carrier detection and control. Our results significantly advance
microresonator-based comb technology towards a portable and robust mid-IR
spectroscopic device that operates at low pump powers.Comment: 8 pages, 5 figure
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