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 background from "168-Gb/s all-optical wavelength con..."
...With this type SMZ all-optical switch, other groups have demonstrated 336-Gb/s demultiplexing for optical time-division multiplexing ([8], 168-Gb/s wavelength conversion [9], and all-optical 2R or 3R...
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12 citations
12 citations
Cites background or methods from "168-Gb/s all-optical wavelength con..."
...While the XGM effect is accompanied by large chirp and a low extinction ratio, and limited by the relatively slow carrier recovery time within the SOA structure, impressive wavelength conversion of up to 40 Gbit/s and with some degradation even up to 100 Gbit/s (Ellis et al., 1998), has been demonstrated....
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...The proposed wavelength converter based on XGM effect in a wideband traveling wave SOA (TW-SOA) at 40 Gbit/s, is presented in figure 10....
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...Subsequently, wavelength conversion based on the XPM effect with excellent signal quality up to 100 Gbit/s, has been demonstrated (Leuthold et al., 2000) by using a fully integrated and packaged SOA delayed interference configuration that comprises a monolithically integrated delay loop, phase shifter and tunable coupler....
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...…wavelength converters, some techniques are proposed, such as: Fiber Bragg grating at 100 Gbit/s (Ellis et al., 1998), interferometric configuration at 168 Gbit/s (Nakamura et al., 2001), two cascaded SOAs at 170.4 Gbit/s (Manning et al., 2006) and optical filtering at 320 Gbit/s (Liu et al., 2007)....
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...For improving the SOA-based wavelength converters, some techniques are proposed, such as: Fiber Bragg grating at 100 Gbit/s (Ellis et al., 1998), interferometric configuration at 168 Gbit/s (Nakamura et al., 2001), two cascaded SOAs at 170.4 Gbit/s (Manning et al., 2006) and optical filtering at 320 Gbit/s (Liu et al., 2007)....
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11 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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