Takahisa Fujita

100Gbit/s DQPSK Transmission Experiment without OTDM for l00G Ethernet Transport

We demonstrate 100Gbit/s DQPSK transmission experiment over 50km SMF. Without resorting OTDM, 100Gbit/s transmission was enabled with DQPSK format and commercially available electronics. Possibility of DQPSK modulation for future 100G Ethernet transport is verified.In order to realize a future 100-Gb Ethernet (100 GbE) transport, 100-Gb/s transmission without 100-GHz-class electronics and optical time-division-multiplexing technique was demonstrated. By using a differential quadrature phase-shift-keying (DQPSK) modulation format and commercially available electronics, 2- and 50-km transmissions of 100-Gb/s signal were successfully achieved over a standard single mode fiber. The receiver sensitivity, chromatic dispersion, and differential group delay tolerances of 100-Gb/s DQPSK signal were also evaluated. Through these evaluations, the possibility of DQPSK modulation for future 100-GbE transport is verified

High-speed optical FSK modulator for optical packet labeling

We described a novel optical label swapping (OLS) technique for optical packet systems using frequency-shift-keying (FSK) optical labeling. High-speed optical FSK signal can be generated by using an external FSK modulator consisting of four optical phase modulators. The FSK modulator was based on optical single-sideband (SSB) modulation technique, and comprised of traveling-wave electrodes for high-speed frequency switching. We demonstrate 10 Gbps FSK transmission, and simultaneous modulation by FSK and intensity modulation (IM). OLS using double-sideband modulation was also demonstrated, where this technique can be used for a bundled wavelength-domain-multiplexing (WDM) channels without using an array of pumping light sources.

High-speed optical DQPSK and FSK modulation using integrated Mach-Zehnder interferometers

We investigated an integrated optical modulator consisting of two Mach-Zehnder interferometers. The modulator can generate optical signals in various types of modulation formats, which have advantages for long-haul transmission, optical labeling, etc. By using a fabricated versatile optical modulator having traveling-wave electrodes designed for high-speed signals, we demonstrated generation of optical 40Gb/s frequency-shift-keying signals, which can be demodulated by an optical filter. 80Gb/s optical differential quadrature-shift-keying modulation was also demonstrated, where 40Gb/s in-phase and quadrature data were, simultaneously, fed to the modulator.

10 Gbit/s FSK transmission over 130 km SMF using group delay compensated balance detection

By using an integrated optical frequency-shift-keying (FSK) modulator, we demonstrate 10 Gbit/s optical FSK transmission over a 130 km single mode fiber. Fiber dispersion was compensated by a balanced photodetector with an optical delay.

Optical FSK transmission with group delay compensated balance detection

A novel balance detection scheme for high-speed optical frequency-shift-keying (FSK) transmission was proposed. Fiber dispersion can be compensated by a balanced photodetector with an optical delay. 10Gbit/s optical FSK transmission over a 130km single mode fiber was demonstrated, where the FSK signal was generated by using aLiNbO3 high-speed optical FSK modulator.

Integrated LiNbO3 modulator for high-speed optical quadrature phase shift keying

We investigated high-speed optical differential quadrature-shift-keying (DQPSK) modulation using an integrated LiNbO3 modulator with two sub Mach-Zehnder structures. A bias condition monitor technique was also proposed for automatic bias control in DQPSK modulation.

10 Gbit/s FSK transmission over 95 km SMF using an external optical FSK modulator

We demonstrate high-speed optical FSK transmission over a 95 km SMF at 10 Gbit/s using an integrated LiNbO/sub 3/ optical FSK modulator consisting of four phase modulators. FSK signal was demodulated by an optical interleaver.

80 Gb/s optical quadrature phase shift keying modulation using an integrated LiNbO 3 modulator

We demonstrated 80 Gb/s optical differential quadrature-shift-keying modulation, by using a single-chip integrated LiNbO3 modulator with two sub Mach-Zehnder interferometers, where 40 Gb/s in-phase and quadrature data were, simultaneously, fed to the modulator.

10Gbit/s FSK transmission over 95km SMF using a LiNbO3 modulator

We demonstrate high-speed optical frequency-shift-keying (FSK) transmission over a 95km single-mode fiber (SMF) at 10Gbit/s using a LiNbO3 optical FSK modulator and an optical interleaver. The measured eye diagrams, bit error rate (BER) performances and optical spectrum indicate the FSK modulation is similar to zero chirp non-return-to-zero (NRZ) on-off-keying (OOK) transmission. Therefore, in view of dispersion tolerance, the FSK modulation can be treated as well as NRZ OOK.