Kenichi Uto

A coherent all-solid-state laser array using the Talbot effect in a three-mirror cavity

Lateral mode coupling in a diode-pumped Nd:YAG microchip laser array is demonstrated with a Talbot cavity for the first time. The relatively low laser gains of solid-state lasers compared with diode lasers and CO/sub 2/ lasers, to which the Talbot cavity has already been applied successfully, are solved by employing a novel auxiliary Talbot cavity configuration. A brighter twin-peak far-field pattern indicating an out-of-phase array mode, whose spot is 9.3 times smaller than that obtained by incoherent superposition of the individual microchip laser outputs, is obtained from the phase-locked microchip laser array with a mode-selecting slit. Without the mode-selecting slit, a far-field pattern with a single narrow peak is obtained, showing that the array is locked in an in-phase mode, presumably because of multiple reflections in the auxiliary Talbot cavity.

43 Gb/s DQPSK pre-equalization employing 6-bit, 43GS/s DAC integrated LSI for cascaded ROADM filtering

Electronic pre-equalization for 43 Gb/s DQPSK has been demonstrated for the first time. Waveform distortion caused by bandwidth narrowing to 18.1 GHz by cascaded 10 Gb/s ROADMs has been adequately pre-equalized by a SiGe-BiCMOS LSI with 6-bit, 43 GS/s digital-to-analog converters.

A study on automatic bias control for arbitrary optical signal generation by dual-parallel Mach-Zehnder modulator

A novel automatic bias control (ABC) is proposed to generate arbitrary signals with a dualparallel Mach-Zehnder modulator. We demonstrated the practical generation of arbitrary modulated signals using the proposed scheme.

DSP-based optical modulation technique for long-haul transmission

Fiber nonlinearity and equalization-enhanced phase noise (EEPN) generate rapid perturbations and critically limit the system capacity and range of long-haul optical transmission. It is possible to cancel the rapid perturbations by introducing a particular correlation between multiple signals at the transmitter and analyzing the received signals using digital signal processing. In this paper, we review our proposed techniques to cancel rapid perturbations of polarization multiplexed signals due to fiber nonlinearity and EEPN. Numerical simulation of quaternary phase-shift keying based signals shows 1.2 dB and 0.5 dB improvement respectively from the proposed cancellation techniques for fiber nonlinearity and EEPN.

43 Gb/s DQPSK transmission over fibre with 2450 ps/nm of dispersion using electronic pre-equalization

Electronic pre-equalization of chromatic dispersion for 43 Gb/s DQPSK has been demonstrated employing a developed test chip. The chip enables the BER in fibre with 2450 ps/nm of dispersion to be improved to 7.6E-05 without an optical dispersion compensator.

Compact multi-chip modules with integrated functions for 10-Gbps lightwave transceivers

Summary form only given. Recently, as various 10-Gbps devices have been developed, reduction of size as well as cost of 10-Gbps lightwave transceivers is required. To meet this demand, compact modules having integrated transceiver functions will become one of the promising candidates, and we have already developed compact multi-chip-modules (MCMs) for high-speed lightwave transmitters and receivers. In this paper, we have developed two more MCMs for 10-Gbps receivers and confirmed the applicability of all developed MCMs for 10-Gbps lightwave transceivers.

Extended-Temperature Operation (−40 °C to +95 °C) of an EML TOSA Employing an Athermal Optical System

An electroabsorption-modulated laser (EML) transmitter optical sub-assembly (TOSA) employing an athermal optical system has been demonstrated for extended-temperature operation from -40 °C to 95 °C. The output power variation of the TOSA was held to <;0.3 dB over this wide temperature range because of optical compensation using the thermo-optical properties of the plastic lens. A 0.8-dB improvement over the variation without this compensation was confirmed. Since the TOSA has sufficient electrical bandwidth for 20-Gb/s operation, clear eye openings with an extinction ratio of over 9.7 dB were obtained over the wide temperature range. The heat sink, the size of which was optimized for operation of the EML at 55 °C, enabled the TOSA to operate over the wide temperature range without thermal runaway. As a result, power consumption of <;0.42 W was achieved over the temperature range.

SMF 300 km transmission experiment by using a newly developed 10 Gbit/s lightwave transceiver with an electro-absorption modulator integrated LD

10-Gbit/s lightwave transceiver with an EA/LD module has been newly developed to meet the STM-64 interface. The back-to-back receiver sensitivity of -16.8 dBm and SMP-300 km amplified transmission experiment with the power penalty of 0.6 dB have been successfully achieved.