Low-Phase-Noise Clock Recovery From NRZ Signal and Simultaneous NRZ-to-RZ Format Conversion
TL;DR: 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 is proposed and demonstrated.
Abstract: 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.
Citations
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TL;DR: A multifunctional optical switching unit based on the bidirectional liquid crystal on silicon (LCoS) and semiconductor optical amplifier (SOA) architecture and Add/drop, wavelength conversion, format conversion, and WDM multicast are experimentally demonstrated.
Abstract: We propose a multifunctional optical switching unit based on the bidirectional liquid crystal on silicon (LCoS) and semiconductor optical amplifier (SOA) architecture. Add/drop, wavelength conversion, format conversion, and WDM multicast are experimentally demonstrated. Due to the bidirectional characteristic, the LCoS device cannot only multiplex the input signals, but also de-multiplex the converted signals. Dual-channel wavelength conversion and format conversion from 2 × 25Gbps differential quadrature phase-shift-keying (DQPSK) to 2 × 12.5Gbps differential phase-shift-keying (DPSK) based on four-wave mixing (FWM) in SOA is obtained with only one pump. One-to-six WDM multicast of 25Gbps DQPSK signals with two pumps is also achieved. All of the multicast channels are with a power penalty less than 1.1 dB at FEC threshold of 3.8 × 10−3.
14 citations
TL;DR: In this paper, a frequency-doubling optoelectronic oscillator (FD-OEO) using tandem Mach-Zehnder modulators (MZMs) biased at the peak transmission point is proposed and experimentally demonstrated.
6 citations
TL;DR: In this paper, the authors proposed a novel notch-filtering scheme for bit-rate transparent all-optical NRZ-to-PRZ format conversion based on a two-degree-of-freedom optimally designed fiber Bragg grating.
Abstract: We propose a novel notch-filtering scheme for bit-rate transparent all-optical NRZ-to-PRZ format conversion. The scheme is based on a two-degree-of-freedom optimally designed fiber Bragg grating. It is shown that a notch filter optimized for any specific operating bit rate can be used to realize high-Q-factor format conversion over a wide bit rate range without requiring any tuning.
4 citations
TL;DR: 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.
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.
2 citations
11 Nov 2014
TL;DR: The dual-channel wavelength conversion and format conversion from 2×25 Gbps DQPSK signals to 2 × 12.5 Gbps DPSK based on FWM in SOA using only one pump is experimentally demonstrated.
Abstract: We experimentally demonstrate the dual-channel wavelength conversion and format conversion from 2×25 Gbps DQPSK signals to 2 × 12.5 Gbps DPSK based on FWM in SOA using only one pump. About 0.5-dB sensitivity improvement at FEC threshold for DPSK1 is achieved and 0.4-dB power penalty is paid for DPSK2.
References
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20 Sep 1998
TL;DR: In this paper, a simple all-optical regeneration technique is described, which suppresses the noise in "zeros" and the amplitude fluctuations in "ones" of return-to-zero optical data streams.
Abstract: A simple all-optical regeneration technique is described. The regenerator suppresses the noise in "zeros" and the amplitude fluctuations in "ones" of return-to-zero optical data streams. Numerical simulations and experimental results are presented.
515 citations
"Low-Phase-Noise Clock Recovery From..." refers background in this paper
...RZ format is also more frequently deployed than NRZ format in optical signal processing applications, which are essential for future all-optical networks, because its high peak power and low duty cycle are in favor of introducing sufficient nonlinearity in materials such as highly nonlinear fibers [3], or reducing inter-symbol interference in materials such as semiconductor optical amplifiers [4]....
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TL;DR: In this paper, a comprehensive treatment of optically preamplified direct detection receivers for non-return-tozero (NRZ) and return-to-zero (RZ) on/off keying modulation, taking into account the influence of different (N)RZ optical pulse shapes, specified at the receiver input, and filter transfer functions; optical Fabry-Perot filters (FPFs) and Bragg gratings as well as electrical fifth-order Bessel and first-order RC low-pass filters are considered.
Abstract: We present a comprehensive treatment of optically preamplified direct detection receivers for non-return-to-zero (NRZ) and return-to-zero (RZ) on/off keying modulation, taking into account the influence of different (N)RZ optical pulse shapes, specified at the receiver input, and filter transfer functions; optical Fabry-Perot filters (FPFs) and Bragg gratings as well as electrical fifth-order Bessel and first-order RC low-pass filters are considered. We determine optimum optical and electrical filter bandwidths and analyze the impact of bandwidth deviations on receiver sensitivity. Optimum receiver performance relies on a balance between noise and intersymbol interference (ISI) for NRZ transmission, while for RZ reception detection noise has to be traded against filter-induced signal energy rejection. Both for NRZ and 33% duty cycle RZ, optical filter bandwidths of around twice the data rate are found to be optimum. Receivers using RZ coding are shown to closely approach the quantum limit, and thus to outperform NRZ-based systems by several decibels. We further analyze the impact of important degrading effects on receiver sensitivity and optimum receiver bandwidths, including receiver noise, finite extinction ratio, chirp, and optical carrier frequency (or optical filter center frequency) fluctuations.
170 citations
"Low-Phase-Noise Clock Recovery From..." refers background in this paper
...NON-RETURN-TO-ZERO (NRZ) and return-to-zero (RZ) data formats may be selectively employed in optical networks demanding high reliability and low cost [1], [2]....
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TL;DR: A clock extraction scheme was demonstrated using an optoelectronic oscillator from high-speed nonreturn-to-zero (NRZ) signal and a theoretical model on the locking range of the oscillator was presented.
Abstract: A clock extraction scheme was demonstrated using an optoelectronic oscillator from high-speed nonreturn-to-zero (NRZ) signal A theoretical model on the locking range of the oscillator was presented A 10-GHz clock with a timing jitter of 04 ps was extracted from 10-Gb/s NRZ signal and a locking range of 800 kHz was achieved NRZ to return-to-zero (RZ) data format conversion was also performed simultaneously with the NRZ clock extraction
73 citations
TL;DR: The feasibility of all-optical clock recovery from non-return-tozero (NRZ) data with a simple NRZ-to-pseudo-RZ (PRZ) converter based on the self-phase modulation (SPM) of a semiconductor optical amplifier (SOA) is empirically presented in this article.
Abstract: The feasibility of all-optical clock recovery (CR) from non-return-to-zero (NRZ) data with a simple NRZ-to-pseudo-RZ (PRZ) converter based on the self-phase modulation (SPM) of a semiconductor optical amplifier (SOA) is empirically presented The SPM induces a frequency chirp at every leading edge of the NRZ data passing through the SOA The SPM-induced chirp component is extracted by an optical grating bandpass filter and then transformed to PRZ data with a low polarisation dependency of ~07 dB By transmitting the PRZ data into a mode-locked Er-doped fibre laser, all-optical CR has been achieved at 25 Gbit/s
46 citations
"Low-Phase-Noise Clock Recovery From..." refers background in this paper
...sively investigated for decades and are usually demonstrated separately [2], [5], which tremendously increase the system complexity and system cost....
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TL;DR: In this paper, a dual-output intensity modulator (IM) is implemented using a polarization modulator, which modulates the later injected continuous-wave (CW) probe and the NRZ signal.
Abstract: Optical signal processing, including clock recovery, nonreturn-to-zero (NRZ) to return-to-zero (RZ) or to carrier-suppressed return-to-zero (CSRZ) format conversions, serial-to-parallel conversion, and optical regeneration in NRZ systems using a frequency-doubling optoelectronic oscillator (OEO) is investigated. The key device in the OEO is a dual-output intensity modulator (IM), which is implemented using a polarization modulator (PolM). If a continuous-wave (CW) probe along with a multichannel NRZ signal is injected into the OEO, an electrical clock at half the data rate of the NRZ signal will be generated. When the electrical clock is fed back into the PolM-based IM, it will modulate the later injected CW probe and the NRZ signal, thus carving the NRZ signal to be an RZ/CSRZ signal at the same data rate or an RZ signal at half the data rate of the NRZ signal. Meanwhile, the CW probe is also carved to be an optical pulse train with a frequency equal to the data rate or half the data rate of the NRZ signal. Multichannel line-rate and prescaled clock recovery, NRZ-to-RZ/CSRZ conversion, 1:2 serial-to-parallel conversion, and synchronous-modulation-based regeneration are thus realized. An experiment is performed with all the aforementioned signal processing functions verified.
44 citations
"Low-Phase-Noise Clock Recovery From..." refers methods in this paper
...Thus, optoelectronic oscillator (OEO) based schemes are employed [6], [7] for the inherent merits of simple, robust and simultaneous operation of CR from NRZ signal and NRZ-to-RZ format conversion....
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...Compared to the conventional MZI or polarization modulator (PolM) based schemes [6], [7], the proposed one can realize simultaneous CR and NRZ-to-RZ format conversion with a lower duty cycle of 25% with the incident NRZ signal....
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