Nrz to rz converter

Bigo, O. Leclerc, and E. Topics Quantum Electron. Kawaguchi, Y. Yamayoshi, and K. CLEO, , pp. Here, is the small signal gain, is the SOA length, [3] D. Norte and A. The small signal gain for SOA1. Mikkelsen, M. Vaa, H. Poulsen, S. Danielsen, C. Kloch, P. Hansen, K. Stubkjaer, K. Wunstel, K. Daub, E. Lach, performance for the output signal. We used a bit data pattern G. Laube, W. Idler, M. Schilling, and S. To evaluate the effect of the ripples on the converted NRZ 33, pp.

Park, L. We always look forward to amiable reviews and recommendations, online as well as offline. All tools have been tested, but we assume no liability for the correctness of results. To determine the averaged roughness depth Rz , a measuring segment is first established and, in turn, this is divided into usually five individual measuring lengths of equal size.

The range of the two extreme values in the roughness profile for the respective, individual sections is subsequently divided by the number of measuring sections. The arithmetic average roughness value Ra describes the arithmetic average of all deviations in the roughness profile from the median line within the measuring length. We've also updated our Privacy Notice. Click here to see what's new. Optical regenerative nonreturn-to-zero NRZ to return-to-zero RZ format conversion using a lithium niobate phase modulator and a lithium niobate intensity modulator is proposed and demonstrated.

The key advantage of the proposed format converter is that the converted RZ signal has a very small pulse width, which can be multiplexed to a higher bit rate using optical time division multiplexing technology. The operation can greatly reduce the timing jitter of the degraded NRZ signal due to the regenerative property of the proposed scheme.

Besides, the format converter can also support multi-channel operation. An experiment is performed with the feasibility of the scheme demonstrated.

Digital optical communications primarily employ conventional data modulation format of either non-return-to-zero NRZ in a wavelength division multiplexing WDM network or return-to-zero RZ in an optical time division multiplexing OTDM network. Considering the different scale and requirement of the future optical networks, the two modulation formats may be selectively used [ 1 ].

In this regard, all-optical NRZ-to-RZ format conversion is of great importance to transparently and seamlessly connect the optical networks operating with different modulation formats. Since the optical NRZ signals introduced to the format converter may be degraded by long-distance fiber transmission, it is desirable that the format converter has the capability to restore the quality of degraded signals. In addition, the format converter should be able to simultaneously convert multi-channel NRZ signals to RZ signals due to the multi-channel nature of the WDM networks.

Previously, optical NRZ-to-RZ conversion has been demonstrated by various approaches including the use of high nonlinearity fiber HNLF [ 2 ], semiconductor optical amplifier SOA [ 2 — 6 ], microring resonator [ 7 ], optoelectronic oscillators [ 8 , 9 ] and optical modulator [ 10 ]. However, the schemes in [ 2 — 7 ] which are based on optical nonlinearity, would introduce serious interchannel crosstalk when applied to a multi-channel system.

The methods proposed in [ 8 — 10 ] can support multi-channel operation, but the generated RZ signals have large pulse widths. The structure is similar to the schemes for the generation of ultrashort optical pulses [ 11 — 14 ].

This RZ signal is further multiplexed to have a much higher data rate. The high quality of the converted RZ signal ensures the excellent transmission performance of the signal in a fiber link. Besides, multi-channel operation can also be achieved based on the proposed format converter. A local electrical clock generated by a radio frequency RF source is split into two signals to drive the two modulators. The relative phase of the two signals is adjusted by an electrical phase shifter.

In practice, the local electrical clock can be extracted from the incident NRZ signal using an optoelectronic oscillator, as demonstrated in [ 8 , 9 ]. The principle of the proposed method can be understood by the schematic shown on the right of Fig. First, the phase modulation in the PM introduces a periodic nonlinear positive and negative chirp across the input NRZ signal.

At the same time, the timing jitter of the NRZ signal is greatly suppressed by the synchronous modulation in the IM [ 15 ]. The phase difference between the driving signals to the PM and the IM is controlled and optimized by the phase shifter so that the negative chirp part is selected by the IM while the positive chirp part is suppressed.

After passing through the DCF with positive dispersion, the chirped RZ signal is compressed and the duty cycle is greatly reduced. In our scheme, the dispersion medium is crucial for the generation of RZ signal with a small duty cycle. It should be noted that a PM and a dispersion medium can realize optical Fourier transformation and reduce the timing jitter of an optical signal [ 16 ].

Dotted line: chirp of the signal; solid line: waveform of the signal. Since the DCF used in the scheme is relatively short, the fiber loss and nonlinearity parameter are neglected in our simulation. However, the pedestal may exist in the converted RZ signal since the nonlinear chirp induced by the PM could not be completely compensated by the DCF even with an optimal length.

The insets in Fig. Since the converted signal is Gaussian-like [ 14 ] and the Gaussian pulse is considered to be pedestal-free, the pedestal of the converted RZ signal is evaluated by comparing the converted signal with a Gaussian pulse which has the same peak power and pulse width.

As can be seen from Fig. Experiments based on the experimental setup shown in Fig. Two continuous-wave CW light at wavelengths of The average power of each channel is amplified to 4. The half-wave voltages of the PM and IM are 3. The eye diagrams of the optical signals are observed by a sampling oscilloscope Agilent A and the bit error rate BER curves are measured by a bit-error rate tester Agilent NB combined with a receiver without an optical preamplifier.

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