106 research outputs found
Broadband wavelength conversion at 40Gb/s using long serpentine As2S3 planar waveguides
We demonstrate broadband wavelength conversion of a 40 Gb/s
return-to-zero signal by cross-phase modulation in a newly developed
chalcogenide glass waveguide based photonic chip. These new serpentine
As2S3 waveguides offer a nonlinear coefficient ≈1700 W-1km-1 with 5×
lower propagation loss over a length of 22.5 cm which ensures the full
propagation length contributes towards the nonlinear process. This reduces
the peak operating power thereby allowing a ×4 increase in the data rate
compared with previous results. Spectral measurements show the device
operates over a span of 40 nm while system measurements show just over 1
dB of power penalty at a bit-error rate of 10-9. This is primarily due to the
compact planar waveguide design which minimizes the effect of groupvelocity
dispersion
Dispersion engineered As2S3 planar waveguides for broadband four-wave mixing based wavelength conversion of 40 Gb/s signals
We demonstrate broadband wavelength conversion of a 40 Gb/s
return-to-zero signal using four-wave-mixing (FWM) in a dispersion
engineered chalcogenide glass waveguide. The 6 cm long planar rib
waveguide 2 μm wide was fabricated in a 0.87 μm thick film etched 350nm
deep to correspond to a design where waveguide dispersion offsets the
material leading to near-zero dispersion in the C-band and broadband phase
matched FWM. The reduced dimensions also enhance the nonlinear
coefficient to 9800 W-1km-1 at 1550 nm enabling broadband conversion in a
shorter device. In this work, we demonstrate 80 nm wavelength
conversions with 1.65 dB of power penalty at a bit-error rate of 10-9.
Spectral measurements and simulations indicate extended broadband
operation is possible
Long, low loss etched As2S3 chalcogenide waveguides for all-optical signal regeneration
We report on the fabrication and optical properties of etched
highly nonlinear As2S3 chalcogenide planar rib waveguides with lengths up
to 22.5 cm and optical losses as low as 0.05 dB/cm at 1550 nm - the lowest
ever reported. We demonstrate strong spectral broadening of 1.2 ps pulses,
in good agreement with simulations, and find that the ratio of nonlinearity
and dispersion linearizes the pulse chirp, reducing the spectral oscillations
caused by self-phase modulation alone. When combined with a spectrally
offset band-pass filter, this gives rise to a nonlinear transfer function
suitable for all-optical regeneration of high data rate signals
Single parameter optimization for simultaneous automatic compensation of multiple orders of dispersion for a 1.28 Tbaud signal
We report the demonstration of automatic higher-order dispersion compensation for the transmission of 275 fs pulses associated with a Tbaud Optical Time Division Multiplexed (OTDM) signal. Our approach achieves simultaneous automatic compensation for 2nd, 3rd and 4th order dispersion using an LCOS spectral pulse shaper (SPS) as a tunable dispersion compensator and a dispersion monitor made of a photonic-chip-based all-optical RF-spectrum analyzer. The monitoring approach uses a single parameter measurement extracted from the RF-spectrum to drive a multidimensional optimization algorithm. Because these pulses are highly sensitive to fluctuations in the GVD and higher orders of chromatic dispersion, this work represents a key result towards practical transmission of ultrashort optical pulses. The dispersion can be adapted on-the-fly for a 1.28 Tbaud signal at any place in the transmission line using a black box approach
Highly-nonlinear chalcogenide glass devices for high-speed signal processing and characterization
We review the latest advances in dispersion-shifted Chalcogenide waveguides enabling highly nonlinear and low dispersion planar rib circuits of centimetre length. Its performance advantages for more broadband and higher speed nonlinear signal processing are shown
Terahertz bandwidth RF spectrum analysis of femtosecond pulses using a chalcogenide chip
We report the first demonstration of the use of an RF spectrum
analyser with multi-terahertz bandwidth to measure the properties of
femtosecond optical pulses. A low distortion and broad measurement
bandwidth of 2.78 THz (nearly two orders of magnitude greater than
conventional opto-electronic analyzers) was achieved by using a 6 cm long
As2S3 chalcogenide waveguide designed for high Kerr nonlinearity and near
zero dispersion. Measurements of pulses as short as 260 fs produced from a
soliton-effect compressor reveal features not evident from the pulse’s
optical spectrum. We also applied an inverse Fourier transform numerically
to the captured data to re-construct a time-domain waveform that resembled
pulse measurement obtained from intensity autocorrelation
Simultaneous multi-impairment monitoring of 640 Gb/s signals using photonic chip based RF spectrum analyzer
We report the first demonstration of simultaneous multiimpairment
monitoring at ultrahigh bitrates using a THz bandwidth
photonic-chip-based radio-frequency (RF) spectrum analyzer. Our approach
employs a 7 cm long, highly nonlinear (γ ≈9900 /W/km), dispersion
engineered chalcogenide planar waveguide to capture the RF spectrum of an
ultrafast 640 Gb/s signal, based on cross-phase modulation, from which we
numerically retrieve the autocorrelation waveform. The relationship
between the retrieved autocorrelation trace and signal impairments is
exploited to simultaneously monitor dispersion, in-band optical signal to
noise ratio (OSNR) and timing jitter from a single measurement. This novel
approach also offers very high OSNR measurement dynamic range (> 30
dB) and is scalable to terabit data rates
Chip-based Brillouin processing for carrier recovery in coherent optical communications
Modern fiber-optic coherent communications employ advanced
spectrally-efficient modulation formats that require sophisticated narrow
linewidth local oscillators (LOs) and complex digital signal processing (DSP).
Here, we establish a novel approach to carrier recovery harnessing large-gain
stimulated Brillouin scattering (SBS) on a photonic chip for up to 116.82
Gbit/sec self-coherent optical signals, eliminating the need for a separate LO.
In contrast to SBS processing on-fiber, our solution provides phase and
polarization stability while the narrow SBS linewidth allows for a
record-breaking small guardband of ~265 MHz, resulting in higher
spectral-efficiency than benchmark self-coherent schemes. This approach reveals
comparable performance to state-of-the-art coherent optical receivers without
requiring advanced DSP. Our demonstration develops a low-noise and
frequency-preserving filter that synchronously regenerates a low-power
narrowband optical tone that could relax the requirements on very-high-order
modulation signaling and be useful in long-baseline interferometry for
precision optical timing or reconstructing a reference tone for quantum-state
measurements.Comment: Part of this work has been presented as a postdealine paper at CLEO
Pacific-Rim'2017 and OSA Optic
Breakthrough switching speed with an all-optical chalcogenide glass chip: 640 Gbit/s demultiplexing
We report the first demonstration of error-free 640 Gbit/s
demultiplexing using the Kerr non-linearity of an only 5 cm long
chalcogenide glass waveguide chip. Our approach exploits four-wave
mixing by the instantaneous nonlinear response of chalcogenide. Excellent
performance is achieved with only 2 dB average power penalty and no
indication of error-floor. Characterisation of the FWM efficiency for the
chalcogenide waveguide is given and confirms the good performance of the
device
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