Masakazu Takabayashi

Tunable dispersion equalizer with a divided thin-film heater for 40-Gb/s RZ transmissions

We have developed tunable dispersion equalizers with a chirped fiber grating on the divided thin-film heater. The divided thin-film heater took an important role in the control of dispersion and dispersion slope. We successfully demonstrated the dispersion control from -304 to -196 ps/nm, the dispersion slope control from +100 to -300 ps/nm/sup 2/, and good performance in 40-Gb/s return-to-zero transmission by using this tunable dispersion equalizer.

Tunable dispersion slope compensator with a chirped fiber grating and a divided thin-film heater for 160-Gb/s RZ transmissions

We have developed the tunable dispersion slope compensator with a chirped fiber grating and a divided thin-film heater composed of 32 thin-film heaters for single-channel 160-Gb/s return-to-zero (RZ) transmission. We successfully demonstrated the dispersion slope change between -20 and +20 ps/nm/sup 2/ and ability of this dispersion slope compensation in 160-Gb/s RZ transmission by the simulations.

Tunable dispersion equalizer with a divided thin film heater

We developed tunable dispersion equalizer with a chirped fiber grating and a divided thin film heater composed thirty-two thin film heaters. The divided thin film heater took an important role in the control of dispersion and dispersion slope, moreover the correction of group delay ripples. We successfully demonstrated the dispersion change from -304 ps/nm to -196 ps/nm and the dispersion slope change from +100 ps/nm/sup 2/ to -300 ps/nm/sup 2/.

Tunable DFB Laser Array Integrated With Mach–Zehnder Modulators for 44.6 Gb/s DQPSK Transmitter

A tunable distributed feedback (DFB) laser array integrated with Mach-Zehnder modulators (TLA-MZMs) for a 44.6 Gb/s differential quadrature phase shift keying (DQPSK) transmitter has been developed. The TLA-MZMs covers 98 wavelength channels with the 50 GHz ITU-T grid in the L-band. The side-mode suppression ratio for all channels was over 47 dB. DC extinction ratios over 25 dB were achieved for the MZMs. Our design achieves both the low modulation voltage (2 Vπ) less than 3 Vpp and the low-excess loss less than 1 dB. 44.6 Gb/s DQPSK modulation with a low driving voltage of 3 V was successfully demonstrated.

Automatically tracked dispersion compensation with penalty-free tunable dispersion equalizer for 40 Gbit/s systems

The automatic control of a tunable dispersion equalizer by means of a bit error monitor was demonstrated. The tunable dispersion equalizer developed consists of a chirped fiber grating and divided thin film heaters. From the tests of the step response and the automatic DEQ control, we confirmed that the tunable dispersion equalizer based on the grating and heaters is suitable for adaptive dispersion compensation of dispersion variations caused by slowly varying environmental conditions with a fluctuation rate of several minutes or more.

Tunable dispersion compensator with twin chirped fiber gratings for polarization mode dispersion and chromatic dispersion

We have developed new tunable dispersion compensators with twin chirped fiber gratings for polarization mode dispersion (PMD) and chromatic dispersion (CD), simultaneously, and successfully demonstrated their ability to change differential group delay (DGD) and chromatic dispersion, independently. The tuning range for the DGD and CD are 150 ps and 200 ps/nm, respectively. The validity of this device for ultra high speed optical communication was confirmed by the simulations of 43 Gbit/s CS-RZ optical transmission.

Tunable polarization mode dispersion compensator with chirped fiber Bragg gratings

We have developed tunable polarization mode dispersion (PMD) compensators and successfully demonstrated to change differential group delay (DGD) from several ps to 90 ps and to compensate DGD in 43 Gbit/s RZ optical transmission experiment.

Tunable dispersion slope compensator with a chirped fiber grating for 160-Gb/s RZ transmissions

We have developed the tunable dispersion slope compensator with a chirped fiber grating for 160-Gb/s transmissions. We successfully demonstrated the dispersion slope change from -20 ps/nm/sup 2/ to +20 ps/nm/sup 2/ and ability of this dispersion slope compensation in 160-Gb/s RZ transmissions.

Low Power Consumption L-Band Tunable Laser Diode with Backside Waveguides

A low power consumption tunable DFB laser diode array, integrated with backside waveguides, is experimentally demonstrated. Fiber output power of 14 dBm was obtained in full L-band with module power consumption less than 3 W.

Photosensitivity in boron-codoped germanosilicate films formed by tetraethylorthosilicate plasma enhanced chemical vapor deposition method without hydrogen loading

Recently, many researchers have been studying optical waveguide devices using photo-induced Bragg grating for their application to wavelength division multiplexing (WDM) communication systems.