B. Milivojevic

5.94-Tb/s 1.49-b/s/Hz (40/spl times/2/spl times/2/spl times/40 Gb/s) RZ-DQPSK polarization-division multiplex C-band transmission over 324 km

The combination of return-to-zero differential quadrature phase-shift keying with polarization-division multiplex, a 16-ary modulation scheme, allows for ultimate spectral efficiency. We raise C-band fiber capacity with phase-shift keying transmission beyond previously reported figures, achieving forward-error correction limit performance over four fiber spans.

1.6-b/s/Hz 160-Gb/s 230-km RZ-DQPSK polarization multiplex transmission with tunable dispersion compensation

A 160-Gb/s (4/spl times/40 Gb/s) return-to-zero differential quadrature phase-shift keying polarization-division multiplex transmission is demonstrated with Q>15.6 dB in one of eight 100-GHz-spaced wavelength-division-multiplex channels after 230 km of fiber. Residual chromatic dispersion (CD) is equalized by a thermally tunable CD compensator for the 192.5-THz channel. Polarizations, in-phase and quadrature data channels are demultiplexed using a LiNbO/sub 3/-based automatic polarization control and a 1-bit interferometer, respectively.

Automatic tunable chromatic dispersion compensation at 40 gb/s in ASK and DPSK, NRZ, and CSRZ 263-km transmission experiments

Chromatic dispersion (CD) in single-mode optical fiber distorts pulses and is a big obstacle for the installation of long-haul dynamically routed transmission systems, especially at 40 Gb/s. Here the automatic residual CD compensation of a 263-km fiber link in the range -300 to -700 ps/nm is demonstrated for nonreturn-to-zero amplitude-shift keying (NRZ-ASK), carrier-suppressed return-to-zero (CSRZ)-ASK, NRZ differential phase-shift keying (DPSK), and CSRZ-DPSK modulation formats at 40 Gb/s. A thermally tunable dispersion compensator minimizes residual CD, which is measured by a synchronous arrival time detection scheme. The measured transmission penalty with online CD compensation is between /spl plusmn/1.2 dB for various link lengths and compensated CD values.

Signed online chromatic-dispersion monitoring by synchronous detection of FM-induced arrival-time modulations in the clock-recovery phase-locked loop

Feature Issue on Optical Performance Monitoring (OPM). Chromatic dispersion (CD) in optical single-mode fibers, i.e., the wavelength dependence of the propagation delay, distorts pulses and is a big problem in 10- and 40-Gbit/s transmission systems. Adjustable drop-in CD compensators require an online CD detection. For this purpose, we modulate the optical power of the laser in a 40-Gbit/s transmitter by 1.2% (rms) at a frequency of 5 MHz. In the presence of CD, the associated periodic optical frequency variation modulates the signal arrival time, which is measured by synchronous (lock-in) detection of an error signal in the clock recovery of the receiver. CD as large as -268 to +350 ps/nm is detected including its sign, more than by any comparable technique. The uncertainty of measured arrival-time modulations can be as low as 100 attoseconds. Moreover, no extra optics or high-frequency electronics are needed, which makes this method extremely cheap to implement. Results are given for nonreturn to zero and carrier-suppressed return to zero (CSRZ), intensity modulation, and differential phase-shift keying.

1.6-Tb/s (40/spl times/40 Gb/s) transmission over 44,...,94 km of SSMF with adaptive chromatic dispersion compensation

Full-band 1.6-Tb/s adaptive chromatic dispersion compensation is demonstrated for the first time. A multichannel tunable dispersion compensator is automatically controlled by arrival time detection on one out of 40 wavelength-division-multiplexed transmitted channels.

5.94 Tbit/s (40×2×2×40 Gbit/s) capacity of a FBG-based multichannel tunable -700 to -1200 ps/nm dispersion compensator

In this paper, we investigate the capacity limit of colourless slope-matched tunable dispersion compensator based on Fiber Bragg grating technology. This compensator was initially designed for 10 Gbit/s operation with a channel bandwidth of at least 35 GHz. The compensator performance was assessed on a 40 channel, 2x2x40 Gbit/s DQPSK system, without and with polarization division multiplexing, which yield total raw data rate of 3.2 and 6.4 Tbit/s respectively. The compensator settings ranged between -700 (41.5 km SSMF) and about -1200 ps/nm (73.8 km SSMF). The measured Q factors of all channels are all above the FEC limit, equivalent to quasi error-free net capacities of 5.94 Tbit/s.

Tunable dispersion compensation experiment in 5.94 Tb/s WDM transmission system

The capacity limit of a thermally controlled fiber Bragg grating-based chromatic dispersion compensator, which was initially designed for 10 Gb/s operation, was investigated in a 40 Gb/s system. A CS-RZ DQPSK polarization division multiplex (PolDM) system was used as a testbed. An equivalent quasi error-free 5.94 Tb/s capacity was demonstrated when dispersion of up to 73.8 km of SSMF was compensated. The dispersion slope compensation was satisfactory for C-band operation. Additionally, it was found that the compensator introduced band-pass filtering behaviour, which reduced the compensator bandwidth as the dispersion setting was increased. It was also found that even after 41.5 km, there was around 2 dB penalty introduced to DQPSK system while 5 dB penalty to DQPDK-PolDM, referring to BER of 10-5.

Adaptive chromatic dispersion compensation in 1.6 Tbit/s DPSK and ASK transmission experiments over 44...94 km of SSMF

Chromatic dispersion (CD) in single-mode optical fiber distorts pulses and is a big obstacle against the upgrading of long-haul, dynamically routed wavelength division multiplexed (WDM) transmission systems at 10 Gbit/s and beyond. High-performance adaptive dispersion compensators are required as well as reliable low-cost hardware for the detection of residual CD. Targeting high-capacity metro systems, full-band 1.6-Tb/s (40x40Gbit/s) adaptive CD compensation is demonstrated in this experiment, using CSRZ-ASK and NRZ-DPSK modulation formats. A multichannel dispersion compensator, tunable in the range -700 to -1500 ps/nm, is automatically controlled by arrival time detection in one of the 40 transmitted WDM channels. Dispersion and its slope are tuned simultaneously by a thermal gradient of the grating-based compensator to match the parameters of standard single-mode fiber (SSMF) with lengths between 44 and 94 km.