1,989 research outputs found
A phase-locked frequency divide-by-3 optical parametric oscillator
Accurate phase-locked 3:1 division of an optical frequency was achieved, by
using a continuous-wave (cw) doubly resonant optical parametric oscillator. A
fractional frequency stability of 2*10^(-17) of the division process has been
achieved for 100s integration time. The technique developed in this work can be
generalized to the accurate phase and frequency control of any cw optical
parametric oscillator.Comment: 4 pages, 5 figures in a postscript file. To appear in a special issue
of IEEE Trans. Instr. & Meas., paper FRIA-2 presented at CPEM'2000
conference, Sydney, May 200
Broadly, independent-tunable, dual-wavelength mid-infrared ultrafast optical parametric oscillator
We demonstrate a two-crystal mid-infrared dual-wavelength optical parametric
oscillator, synchronously pumped by a high power femtosecond Yb:fiber laser.
The singly-resonant ring cavity, containing two periodically poled lithium
niobate crystals, is capable of generating two synchronized idler wavelengths,
independently tunable over 30 THz in the 2.9 - 4.2 {\mu}m wavelength region,
due to the cascaded quadratic nonlinear effect. The independent tunability of
the two idlers makes the optical parametric oscillator a promising source for
ultrafast pulse generation towards the THz wavelength region, based on
different frequency generation. In addition, the observed frequency doubled
idler within the crystal indicates the possibility to realize a broadband
optical self-phase locking between pump, signal, idler and higher order
generated parametric lights
Cascaded half-harmonic generation of femtosecond frequency combs in mid-IR
For the growing demand of frequency combs in mid-infrared (mid-IR), known as
the "molecular fingerprint" region of the spectrum [1], down conversion of
near-IR frequency combs through half- harmonic generation offers numerous
benefits including high conversion efficiency and intrinsic phase and frequency
locking to the near-IR pump [2]. Hence cascaded half-harmonic generation
promises a simple path towards extending the wavelength coverage of stable
frequency combs. Here, we report a two-octave down-conversion of a frequency
comb around 1 {\mu}m through cascaded half-harmonic generation with ~64%
efficiency in the first stage, and ~18% in the second stage. We obtain
broadband intrinsically-frequency-locked frequency combs with ~50-fs pulses at
~2 {\mu}m and ~110-fs pulses at ~4 {\mu}m. These results indicate the
effectiveness of half-harmonic generation as a universal tool for efficient
phase- and frequency-locked down-conversion, which can be beneficial for
numerous applications requiring long-wavelength coherent sources
Generation of five phase-locked harmonics by implementing a divide-by-three optical frequency divider
We report the generation of five phase-locked harmonics, f_1: 2403 nm, f_2:
1201 nm, f_3: 801 nm, f_4: 600 nm, and f_5: 480 nm with an exact frequency
ratio of 1 : 2 : 3 : 4 : 5 by implementing a divide-by-three optical-frequency
divider in the high harmonic generation process. All five harmonics are
generated coaxially with high phase coherence in time and space, which are
applicable for various practical uses.Comment: 6 pages, 6 figure
All-Optical Quantum Random Bit Generation from Intrinsically Binary Phase of Parametric Oscillators
True random number generators (RNGs) are desirable for applications ranging
from cryptogra- phy to computer simulations. Quantum phenomena prove to be
attractive for physical RNGs due to their fundamental randomness and immunity
to attack [1]- [5]. Optical parametric down conversion is an essential element
in most quantum optical experiments including optical squeezing [9], and
generation of entangled photons [10]. In an optical parametric oscillator
(OPO), photons generated through spontaneous down conversion of the pump
initiate the oscillation in the absence of other inputs [11, 12]. This quantum
process is the dominant effect during the oscillation build-up, leading to
selection of one of the two possible phase states above threshold in a
degenerate OPO [13]. Building on this, we demonstrate a novel all-optical
quantum RNG in which the photodetection is not a part of the random process,
and no post processing is required for the generated bit sequence. We implement
a synchronously pumped twin degenerate OPO, which comprises two identical
independent OPOs in a single cavity, and measure the relative phase states of
the OPO outputs above threshold as a bit value. We show that the outcome is
statistically random with 99% confidence. With the use of micro- and nanoscale
OPO resonators, this technique offers a promise for simple, robust, and
high-speed on-chip all-optical quantum random number generators
Parallel generation of quadripartite cluster entanglement in the optical frequency comb
Scalability and coherence are two essential requirements for the experimental
implementation of quantum information and quantum computing. Here, we report a
breakthrough toward scalability: the simultaneous generation of a record 15
quadripartite entangled cluster states over 60 consecutive cavity modes
(Qmodes), in the optical frequency comb of a single optical parametric
oscillator. The amount of observed entanglement was constant over the 60
Qmodes, thereby proving the intrnisic scalability of this system. The number of
observable Qmodes was restricted by technical limitations, and we
conservatively estimate the actual number of similar clusters to be at least
three times larger. This result paves the way to the realization of large
entangled states for scalable quantum information and quantum computing.Comment: 4 pages + 7 supplemental-info pages, 6+1 figures, accepted by
Physical Review Letters. One minor revision to main text. One error corrected
in Eq. (18) of Supplemental informatio
Coherence properties of a broadband femtosecond mid-IR optical parametric oscillator operating at degeneracy
We study coherence properties of a χ^(2) optical parametric oscillator (OPO), which produces 2/3-octave-wide spectrum centered at the subharmonic (3120 nm) of the femtosecond pump laser. Our method consists of interfering the outputs of two identical, but independent OPOs pumped by the same laser. We demonstrate that the two OPOs show stable spatial and temporal interference and are mutually locked in frequency and in phase. By observing a collective heterodyne beat signal between the two OPOs we show that one can deterministically choose, by cavity length adjustment, between the two frequency states corresponding to the two sets of modes shifted with respect to each other by half of the laser pulse repetition rate. Moreover, we observe that the existence of two opposite phase states, a known common feature of a parametrically driven n = 2 subharmonic oscillator, reveals itself in our experiment as a common phase, 0 or π, being established through the whole set of some 300 thousand longitudinal modes
Frequency metrology by use of quantum interference
Quantum interference in the rate of two-photon excitation of the 6S1/2 → 6P3/2 → 6D5/2 transition in atomic cesium is exploited to demonstrate phase-sensitive frequency demodulation for an optical interval of 612.5 THz. By thus using atoms as ultrafast nonlinear mixing elements, we suggest and analyze a new avenue for absolute comparisons of a dense set of frequencies over the range of 200–2000 nm
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