1. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) DB encoder; (b) DBM scheme with precoder. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

2. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic diagram of the transmitter of the 40-Gbit∕s modified DB optical fiber transmission system. (b) Input-output transfer characteristics of the MZIM. Carrier suppression is achieved when the two arms are biased at positive and negative quadrature points on opposite sides of the transfer characteristics. Variation of the optical signal pulse width is obtained via modulation of a clock sequence generated by the pulse carver (not shown). Data modulator operation remains identical for all formats. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

3. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Generic simulation model for duobinary variable-pulse-width transmission. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

4. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. MATLAB Simulink model showing the pulse carver (optical clock sources) and the data dual-drive MZIM for building a variable- pulse-width RZ DB transmitter. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

5. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Electrical filter inserted before modulating the data optical modulator. The filter can be of the Gaussian or raised-cosine type, or a Bessel filter of fifth order can be inserted to reduce the required transmitting signal bandwidth. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

6. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) Optical spectrum as monitored at the output of the 40-Gbit∕s DB transmitter with formats NRZ (dots black), CSRZ with 67% pulse width (red crosses), 50% RZ (blue dots) and RZ33% (magenta asterisks), all normalized with respect to the optical carrier, which is set at 192.52THz. (b) Spectra of CSRZ, NRZ, and RZ DPSK modulation formats obtained by experiment. (Color online only.) Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

7. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Simulink simulation model of the data encoder for the DB format using a differential DPSK encoding scheme. The differential signals can delayed or undelayed, and then added with their inverted versions to transform the three-level electrical signals to two-level signals for driving the data modulator electrodes. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

8. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Simulink simulation model for the propagation of DB-modulated carrier over dispersion-compensated transmission link. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

9. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. (a) BER versus receiver power for 320-km SSMF and 320-km DCF (effective negative 320-km SSMF) transmission. Red curve end circles, experimental CSRZ DPSK transmission with complete compensation. Blue curve and circles, experimental RZ DPSK. Red curve and asterisks, simulated DB. Black curve and squares, simulated DB 50% FWHM alternating-phase modulation. Here 67% DB improves over 50% by 4.2dB. (b) Simulated dispersion tolerance for 40Gbit∕s DB with 67%, 50%, and 33% FWHM: BER versus residual equivalent SSMF length. Launched power 0dBm at output of transmitter. (Color online only.) Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

10. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Experimental and simulated system test bed for CSRZ, NRZ, and RZ DPSK and DB transmission over 328-kmSSMF+320-km DCF and associated EDFAs using balanced receiver: (a) schematic diagram of the test bed; (b) 34-ps∕nm residual dispersion with dispersion-compensated receiver eye diagram of CSRZ DPSK. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

11. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Receiver diagrams after three spans (320km) SSMF fiber, fully compensated, including two in-line optical amplifiers (20-dB gain and 5-dB noise figure): (a) RZDB, 33% FWHM, RZ (b) DB 50% FWHM, and (c) NRZ. DB. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965

12. Date of download: 6/1/2016 Copyright © 2016 SPIE. All rights reserved. Receiver eye diagrams after three spans (320km) of SSMF fiber fully compensated, including two in-line optical amplifiers (20-dB gain and 5-dB noise figure), 40-Gbits∕s transmission. (a) CSRZ, 67% DB, with the integration of a Gaussian electrical filter with 30% bit rate; (b) same as (a), but without filtering at receiver; (c) CSRZ, 67% DB, with raised-cosine filtering at transmitter and no filter at receiver. Figure Legend: From: Optical transmission of variable-pulse-width alternating-phase duobinary modulation: MATLAB Simulink simulation and comparison with carrier-suppressed return-to-zero amplitude-shift-keying experimental transmission Opt. Eng. 2008;47(7):075001-075001-10. doi:10.1117/1.2957965