44 research outputs found
Effects of Raman scattering and attenuation in silica fiber-based parametric frequency conversion
Four-wave mixing in the form of Bragg scattering (BS) has been predicted to
enable quantum noise less frequency conversion by analytic quantum approaches.
Using a semi-classical description of quantum noise that accounts for loss and
stimulated and spontaneous Raman scattering, which are not currently described
in existing quantum approaches, we quantify the impacts of these effects on the
conversion efficiency and on the quantum noise properties of BS in terms of an
induced noise figure (NF). We give an approximate closed-form expression for
the BS conversion efficiency that includes loss and stimulated Raman
scattering, and we derive explicit expressions for the Raman-induced NF from
the semi-classical approach used here.Comment: 14 single col pages, 11 figure
Temporal mode selectivity by frequency conversion in second-order nonlinear optical waveguides
We explore theoretically the feasibility of using frequency conversion by
sum- or difference-frequency generation, enabled by three- wave-mixing, for
selectively multiplexing orthogonal input waveforms that overlap in time and
frequency. Such a process would enable a drop device for use in a transparent
optical network using temporally orthogonal waveforms to encode different
channels. We model the process using coupled-mode equations appropriate for
wave mixing in a uniform second- order nonlinear optical medium pumped by a
strong laser pulse. We find Green functions describing the process, and employ
Schmidt (singular- value) decompositions thereof to quantify its viability in
functioning as a coherent waveform discriminator. We define a selectivity
figure of merit in terms of the Schmidt coefficients, and use it to compare and
contrast various parameter regimes via extensive numerical computations. We
identify the most favorable regime (at least in the case of no pump chirp) and
derive the complete analytical solution for the same. We bound the maximum
achievable selectivity in this parameter space. We show that including a
frequency chirp in the pump does not improve selectivity in this optimal
regime. We also find an operating regime in which high-efficiency frequency
conversion without temporal-shape selectivity can be achieved while preserving
the shapes of a wide class of input pulses. The results are applicable to both
classical and quantum frequency conversion.Comment: 24 pages, 20 figure
Entanglement swapping for generation of heralded time-frequency-entangled photon pairs
Photonic time-frequency entanglement is a promising resource for quantum
information processing technologies. We investigate swapping of
continuous-variable entanglement in the time-frequency degree of freedom using
three-wave mixing in the low-gain regime with the aim of producing heralded
biphoton states with high purity and low multi-pair probability. Heralding is
achieved by combining one photon from each of two biphoton sources via
sum-frequency generation to create a herald photon. We present a realistic
model with pulsed pumps, investigate the effects of resolving the frequency of
the herald photon, and find that frequency-resolving measurement of the herald
photon is necessary to produce high-purity biphotons. We also find a trade-off
between the rate of successful entanglement swapping and both the purity and
quantified entanglement resource (negativity) of the heralded biphoton state.Comment: 17 pages and 9 figures. Version 3 corrects an error in the count rate
theory and calculations, fixes a few grammatical and typographical errors,
improves formatting, and adds the journal referenc