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All-optical modulation format conversion from PSK to ASK based on phase-sensitive amplification
Abstract
With the development of the optics communication system and optical signal modulation technology, the amplitude-shift keying (ASK) and phase-shift keying (PSK) are both used in different optical communication sub-networks. In this paper, a novel all-optical modulation format from PSK to ASK based on phase-sensitive amplification is proposed and demonstrated. Using the nonlinear interference of the single-pump phase-sensitive amplification, the signal wavelength can be preserved while the modulation format is conversed. The proposed scheme provides the flexible intermediate node interface transformation in future optical networks.
... Previous experimental studies have reported the coherent detection of the output of de-aggregation into two non-OOK signals, including (a) de-aggregation of a QPSK signal into two binary phase-shift keying (BPSK) signals [11][12][13][14][15] and (b) deaggregation of a 16-QAM signal into two 4-APSK (amplitudeand phase-shift keying) signals [11,16]. Another experimental demonstration using coherent detection showed the conversion of an input BPSK signal to a single OOK signal [17] based on constellation biasing [18,19]. However, several simulation studies have shown the de-aggregation of a single higher-order modulation format into two lower-order modulation formats, with one of the outputs being OOK [4,20]. ...
Optical data format de-aggregation enables the conversion from a single higher-order phase-encoded data channel coming from a high-bandwidth network into two amplitude-modulated signals that may be commonly used in lower-bandwidth local information systems. We experimentally demonstrate the optical de-aggregation of a 10-Gbit/s quadrature phase-shift keyed (QPSK) signal into two 5-Gbit/s on-off keyed (OOK) signals. Using wave mixing in a highly nonlinear fiber (HNLF), we apply two optical effects simultaneously to the input signal: (a) constellation squeezing, in which the 10-Gbit/s QPSK signal is de-aggregated into two different 5-Gbit/s binary phase-shift keying (BPSK) signals, and (b) constellation biasing, in which the coherent addition of a continuous-wave (CW) bias and the two BPSK signals shifts the data constellation points, resulting in only amplitude modulation and two different 5-Gbit/s OOK signals. The optical signal-to-noise ratio (OSNR) differences at a bit error rate (BER) of 3.8·10⁻³ between the back-to-back (B2B) transmitted OOK signal and the two recovered OOK signals using direct detection are 1.9 dB and 3.2 dB.
... Advanced modulation formats, such as M-ary quadrature amplitude modulation and M-ary phase-shift keying (M-PSK), are widely used in EON as they have ameliorated transmission capacity and spectral efficiency, whereas simple modulation formats have their own characteristics such as high reliability and simplicity. 11,12 Several modulation format conversion techniques have been analyzed by researchers for channel aggregation and deaggregation, for example, conversion from phase-shift keying (PSK) to amplitude shift keying using phase-sensitive amplification (PSA), 13 conversion from on-off keying (OOK) to quadrature phase-shift keying (QPSK) and from binary PSK to 8-PSK as well. 14 Various other modulation format conversions of the 8-PSK signal to two simultaneous QPSK signals at 30 Gb∕s based on PSA, 15 OOK-to 16-quadrature amplitude modulation based on non-linear optical loop mirror, 16 have also been proposed by the researchers. ...
... So, all the PSK signals have similar variances as the QPSK signal. However, there are some research on modulation format conversion [21,22]. If the PSK signals can be converted into the corresponding QAM signals, the proposed MFI method can identify the PSK formats. ...
Blind modulation format identification (MFI) is essential in an elastic optical network (EON) due to unknown modulation format of the received signals. We propose an MFI method for square and non-square quadrature amplitude modulation (QAM) signals, quadrature phase-shift keying (QPSK), 8-QAM, 16-QAM, 32-QAM, 64-QAM, 128-QAM, 256-QAM, 512-QAM, 1024-QAM, and 2048-QAM. We identified these modulation formats by using two identification factors such as the amplitude variance and the optical signal-to-noise ratio (OSNR) of the received signal. The simulation results based on a look-up-table (LUT) and a neural network, respectively, show that the modulation format of the received signals can be identified correctly in the OSNR range of a bit error rate (BER) for communication, better than 10⁻². We also investigate effects of both ONSR measurement errors and residual chromatic dispersion (CD) on the MFI performance.
High-dimensional modulation schemes have become the preferred choice for high data rate transmission. Compared to the conventional square 16QAM, hexagonal 16QAM configuration is less vulnerable to noise. This paper presents a theoretical error performance of uncoded hexagonal 16QAM using a lower computational complex approach.
We proposed and demonstrate an all-optical demodulation and format conversion scheme for multi-channel (carrier suppressed) return-to-zero differential phase shift keying ((CS)RZ-DPSK) signals. By utilizing a single delay interferometer (DI) with half bit delay, multi-channel (CS)RZ-DPSK signals can be demodulated simultaneously at the destructive port of the DI, with the corresponding converted nonreturn-to-zero differential phase shift keying (NRZ-DPSK) signals obtained at the constructive port. The proposed multi-channel operation has been demonstrated for 6*20 Gb/s RZ-DPSK and 6*40 Gb/s CSRZ-DPSK signals, with ~0.8 and 1.2 dB average power penalties for the format conversions respectively.
Phase-sensitive amplification (PSA) has the potential to improve significantly the performance of optical communication systems. PSA is known to occur in χ ⁽²⁾ devices, and in a fiber interferometer, which is an example of a χ ⁽³⁾ device. In this report some four-wave mixing processes are described, which produce PSA directly in fibers.
In this paper, an efficient sparse representation-based method is presented for detecting surface defects. The proposed method uses the sparse degree of coefficient in the redundant dictionary for checking whether the test image is defective or not, and the binary representation of the defective images is obtained, according to the global coefficient feature. Owing to the requirements for the efficiency and detecting quality, the block proximal gradient operator is introduced to speed up the online dictionary learning. Considering the correlation among the testing samples, prior knowledge is applied in the orthogonal-matching-pursuit sparse representation algorithm to improve the speed of sparse coding. Experimental results demonstrate that the proposed detection method can effectively detect and extract the defects of the surface images, and has broad applicability.
A novel advanced modulation format based on Manchester signalling is proposed and assessed for high-speed optical communication systems. The new advanced modulation format known as modified Manchester derived from the combination of Manchester and vestigial sideband (VSB) techniques. Its performance assessed and compared in terms of spectral efficiency, chromatic dispersion tolerance and receiver sensitivity against conventional Manchester, return-to-zero (RZ) and non-RZ (NRZ) (with the same spectral width). The optimisation of the optical filter that performed the VSB filtering on the Manchester signal and its detuning frequency results in the compression of the spectral width of the Manchester signal and thereby enhanced the spectral efficiency of the modified Manchester to about 31.3%. This results in the improvement of dispersion tolerance to ~140 ps/nm. In comparison with conventional modulation formats, the proposed system can improve the dispersion tolerance by three times more than conventional Manchester, which is 44 ps/nm, and twice more than NRZ, which is 51.8 ps/nm and has a better dispersion tolerance of 31 ps/nm than RZ with dispersion tolerance of 109 ps/nm at a bit-error-rate of 10⁻⁹. The improvement in the proposed modulation performance achieved without utilisation of any dispersion compensation module or electronic equalisation.
As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit (ONU) and to perform complex services awareness from the whole view of system in optical line terminal (OLT). Simulation results show that the proposed scheme is able to achieve better quality of services (QoS), in terms of packet loss rate and time delay.
In this paper, a phase erasure and format conversion of phase-shift keying (PSK) to conventional on-off keying (OOK) is proposed and demonstrated theoretically and experimentally. Using a single-pump nondegenerate phase sensitive amplification process in a highly nonlinear fiber, the 0 and 1-bits of the PSK signal obtain different gains through amplification and de-amplification. As a result, the modulation information is transferred onto the amplitude. With an optimized input power difference between the signal and idler, the signal phase information is erased with wavelength preservation after the PSA. The output constellation and eye diagrams show an effective phase erasure and format conversion of PSK to conventional OOK. The error vector magnitude is utilized to evaluate the scheme performance. The proposed scheme provides the flexibility and resiliency for future photonic networks.
As a tunable optical filter, angle-tuned thin film narrowband filter is
widely used in dense wavelength division multiplexing (DWDM) system. In
oblique incidence, the transmitting facular broadens obviously, which
will cause a decrease in transmissivity and rectangular degree of the
filter. The transmitting spectrum characteristics and the transmitting
facular broadening are also influenced by the non-parallel incident and
emergent interfaces' wedge angle of the wedge filter. In the present
paper, the transmitting intensity distribution in different incident
angle of the wedge filter has been calculated, and the influences of the
wedge angle to the transmissivity and the half bandwidth are also
analyzed. The proper wedge angle and incident orientation will improve
the characteristics of the transmitting spectrum. A 100 GHz DWDM
angle-tuned wedge filter was fabricated which has a wedge angle of
0.8°. Compared with the parallel angle-tuned filter, the wedge
filter can enhance the transmissivity and the rectangular degree in
oblique incidence and its tunable wavelength range will increase 10 nm.
Angle-tuned thin film bandpass filter is widely used in DWDM system. In oblique incidence, the bandwidths and central wavelengths of the P-polarization and S-polarization light will separate obviously, which will cause serious polarization dependent loss. These phenomena of the polarization sensitivities are analyzed and a novel non-polarization 100 GHz four-cavity narrowband dielectric thin film stack used in oblique incidence is proposed. The simulation results show that it can eliminate the polarization bandwidths and central wavelengths separation within the incident angle from 0 to 25 and its tunable range can cover the whole C-band.
We propose and demonstrate an improved optoelectronic oscillator based on a dual-parallel Mach-Zehnder modulator for simultaneous low-duty-cycle and low-phase-noise clock recovery from NRZ signal and wavelength-preserved NRZ-to-RZ format conversion. A 25-GHz optical clock with a 25% duty cycle and a 22.5-dB extinction ratio is successfully extracted from the incident 25-Gb/s NRZ signal. Benefiting from the intrinsic property of the optoelectronic oscillator, an electrical clock with a 174-fs root-mean-square timing jitter (100 Hz-10 MHz) is also achieved. Simultaneously, error-free wavelength-preserved NRZ-to-RZ format conversion with a -2-dB power penalty at a bit error rate of 10-9 is demonstrated.
640 Gb/s all-optical ON-OFF keying signal regeneration based on nonlinearities in a periodically poled lithium niobate (PPLN) waveguide is demonstrated and characterized. The data are transferred from the distorted original optical time division multiplexing (OTDM) signal onto a high quality and locally generated 640 GHz clock by pump depletion simultaneously operating a wavelength conversion. The thresholding behavior and the saturation effect of pump depletion in the PPLN waveguide for low and high pump power values, respectively, allow for a noise compression on the wavelength-converted replica of the original signal. The use of a stable clock with a shorter pulsewidth also allows for a sort of sampling of the original OTDM frame in the bit time center, resulting in a pulse reshaping that eliminates all noise contributions on the pulse tails. This operation produces a reduction of the original time jitter of the signal. The sampling operation also results in a compression of the new OTDM frame pulses compensating for the residual chromatic dispersion effects. After having characterized the transfer function of the proposed regeneration scheme, we evaluate its effectiveness as a function of optical signal-to-noise ratio (OSNR), pulse broadening, and time jitter of the input signal. Regeneration performance is measured in terms of bit error rate (BER) and power penalty @ BER = 10-9. Error-free operation can be recovered and maintained over an input signal OSNR range of 8 dB. This results in a BER improvement up to several orders of magnitude, obtained when the input OSNR is reduced by 20 dB with respect to the baseline. The time jitter of input signals with original jitter values from 100 to 300 fs has been reduced of nearly one order of magnitude to values lower than 40 fs. We also demonstrate that a pulse broadening up to 20% of the original pulsewidth can be compensated. Finally, wavelength tunability of the regenerator input and output signal can be, in princi- le, guaranteed over the whole C-band and beyond.
We propose a novel all-optical NRZ-OOK/RZ-BPSK format conversion scheme, using cross-phase modulation effects in a MZI-SOA. We experimentally demonstrate error free conversion at 10.7 Gb/s with a negative power penalty of 2.9 dB
ADS Article Google Scholar
- H F Bai
Article Google Scholar
- J Parra-Cetina
- S Latkowski
- R Maldonado-Basilio
- P Landais