168-Gb/s all-optical wavelength conversion with a symmetric-Mach-Zehnder-type switch
Summary (1 min read)
I. INTRODUCTION
- T HE SCHEME of ultrafast optical networks based on optical-time-division multiplexing (OTDM) technology attracts much attention in terms of not only high capacity but also high flexibility.
- In such networks, the expected bit rates per wavelength channel are over 100 Gb/s, and thus various signal processing at these ultrahigh bit rates will be done in the optical domain.
- Recently, error-free 168-Gb/s DEMUX with the hybrid-integrated SMZ (HI-SMZ) switch [7] has also been demonstrated.
- To utilize the SMZ switches for a wider range of applications such as logic, regeneration [8] , or wavelength conversion [9] , operation excited by higher repetition data-modulated optical pulses is required on top of being ultrafast.
- The wavelength converter operates without logic inversion and keeps the pulse duration almost unchanged from input to output.
II. EXPERIMENTAL SETUP
- The experimental setup for 168-Gb/s wavelength conversion is shown schematically in Fig. 1 .
- The 168-Gb/s signal pulses were generated by modulating the output of the fiber laser with a pseudorandom bit sequence (PRBS) with a length of 2 and then passively multiplexing the modulated pulses.
- The average powers of the signal pulses and of the CW light at the input of the SOA module were 10 and 16 dBm, respectively.
- The time delay provided by the birefringence of the calcite was set to 2.0 ps, which determined the duration of the output pulse.
- Thus, the pulse duration was kept almost unchanged before and after wavelength conversion.
III. RESULTS AND DISCUSSION
- Fig. 2(a) shows the 168-Gb/s output waveform of the DISC measured by a streak camera.
- The trace was recorded as the accumulation of many PRBS pulses, and thus was observed as a regular pulse sequence.
- For 84-Gb/s operation, the power penalty for MUX and DEMUX was estimated to be about 2.5 dB from a separate experiment [7] .
- These power penalties for wavelength conversion are mainly due to a residual pattern effect induced in the SOA by the data-modulated signal pulses.
- The mechanism of suppressing the pattern effect by using the relatively high average power of the CW light is interpreted by the effective reduction in the carrier lifetime of the SOA [4] , [12] .
IV. CONCLUSION
- The authors have achieved error-free all-optical wavelength conversion at 168 Gb/s, which is the highest repetition rate ever reported, with the Delayed Interference Signal-wavelength Converter.
- Low-power-penalty 84-Gb/s operation has also been achieved.
- The authors believe that the present operation is more complete than earlier 100-Gb/s-level experiments because the pulse duration is kept nearly unchanged, logic is noninverted, and high extinction ratio output is obtained.
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Citations
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Cites methods from "168-Gb/s all-optical wavelength con..."
...For example with the UNI configuration (Ultrafast-Nonlinear Interferometer), 80 Gb/s wavelength conversion has been realized and with in the DISC configuration (Delayed-Interference Signal-wavelength Converter) 168 Gb/s has been shown [31, 32]....
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2 citations
2 citations
Cites background from "168-Gb/s all-optical wavelength con..."
...In this extended abstract, two examples are given that indicating how optical signal processing might play role in future optical telecommunication nodes....
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2 citations
Cites methods from "168-Gb/s all-optical wavelength con..."
...Therefore, by using monolithically integrated MZI switches [10, 11] operating up to 160 Gbit/s a further processing time reduction could be possible....
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2 citations
References
207 citations
"168-Gb/s all-optical wavelength con..." refers background in this paper
...In achieving such ultrafast optical signal processing, the Symmetric-Mach–Zehnder (SMZ) all-optical switch family, including the original SMZ switch [1], the Polarization-Discriminating SMZ (PD-SMZ) switch [2], and the Delayed-Interference Signal-wavelength Converter (DISC) [3]–[5] is quite promising....
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184 citations
"168-Gb/s all-optical wavelength con..." refers background in this paper
...In such operation, the pattern effect due to high repetition data-modulated signal pulses is suppressed by injecting unmodulated continuous-wave (CW) light or clock pulses into SOAs at relatively high average power [4], [12]....
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172 citations
"168-Gb/s all-optical wavelength con..." refers background or methods in this paper
...experiments [10] exhibiting ultrafast all-optical wavelength conversion accompanied the conversion from return-to-zero (RZ) to nonreturn-to-zero (NRZ) and/or logic inversion....
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...To date, 100-Gb/s wavelength conversion [10] and 80-Gb/s pulse regeneration [11] have been shown by using the push–pull switching mechanism of the SMZ all-optical switch incorporating semiconductor optical amplifiers (SOAs)....
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156 citations
134 citations
"168-Gb/s all-optical wavelength con..." refers background in this paper
...The DISC consists of a nonlinear waveguide and a delay line, as detailed in [3]....
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...(a) Streak camera trace for DISC output....
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...In achieving such ultrafast optical signal processing, the Symmetric-Mach–Zehnder (SMZ) all-optical switch family, including the original SMZ switch [1], the Polarization-Discriminating SMZ (PD-SMZ) switch [2], and the Delayed-Interference Signal-wavelength Converter (DISC) [3]–[5] is quite promising....
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...3 is the eye diagram for the 168-Gb/s output of the DISC measured after DEMUX....
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...The 168-Gb/s output of the DISC was demultiplexed to 10.5 Gb/s by the HI-SMZ switch [7] to measure eye diagrams and bit error rates (BERs). lation measurement as shown in Fig....
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