250 research outputs found
Optimal WDM Power Allocation via Deep Learning for Radio on Free Space Optics Systems
Radio on Free Space Optics (RoFSO), as a universal platform for heterogeneous
wireless services, is able to transmit multiple radio frequency signals at high
rates in free space optical networks. This paper investigates the optimal
design of power allocation for Wavelength Division Multiplexing (WDM)
transmission in RoFSO systems. The proposed problem is a weighted total
capacity maximization problem with two constraints of total power limitation
and eye safety concern. The model-based Stochastic Dual Gradient algorithm is
presented first, which solves the problem exactly by exploiting the null
duality gap. The model-free Primal-Dual Deep Learning algorithm is then
developed to learn and optimize the power allocation policy with Deep Neural
Network (DNN) parametrization, which can be utilized without any knowledge of
system models. Numerical simulations are performed to exhibit significant
performance of our algorithms compared to the average equal power allocation
Mid-infrared frequency comb spanning an octave based on an Er fiber laser and difference-frequency generation
We describe a coherent mid-infrared continuum source with 700 cm-1 usable
bandwidth, readily tuned within 600 - 2500 cm-1 (4 - 17 \mum) and thus covering
much of the infrared "fingerprint" molecular vibration region. It is based on
nonlinear frequency conversion in GaSe using a compact commercial 100-fs-pulsed
Er fiber laser system providing two amplified near-infrared beams, one of them
broadened by a nonlinear optical fiber. The resulting collimated mid-infrared
continuum beam of 1 mW quasi-cw power represents a coherent infrared frequency
comb with zero carrier-envelope phase, containing about 500,000 modes that are
exact multiples of the pulse repetition rate of 40 MHz. The beam's
diffraction-limited performance enables long-distance spectroscopic probing as
well as maximal focusability for classical and ultraresolving near-field
microscopies. Applications are foreseen also in studies of transient chemical
phenomena even at ultrafast pump-probe scale, and in high-resolution gas
spectroscopy for e.g. breath analysis.Comment: 8 pages, 2 figures revised version, added reference
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