T. Uji

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Impact ionization rates for electrons and holes in

12-channel parallel optical-fiber transmission using a low-drive current 1.3- mu m LED array and a p-i-n PD array

Twelve-channel 14-Mb/s/channel 1-km parallel optical-fiber transmission using a 1*12 low-drive-current 1.3- mu m light-emitting diode (LED) linear array and an InGaAs p-i-n photodiode linear array, with the LED drive current as low as 12 mAp-p/channel, is discussed. No receiver sensitivity degradation has been observed under simultaneous 12-channel operation. The skew was less than 6 ns after transmission through a 1-km-long 12-channel optical-fiber cable, which was sufficiently small for 14-Mb/s parallel transmission. >

DFB laser intermodulation distortion analysis taking longitudinal electrical field distribution into account

DFB laser intermodulation distortion were theoretically analyzed, taking longitudinal electrical field distribution in the laser cavity into account. The modulation distortion mechanism caused by longitudinal electrical field nonuniformity along the laser cavity was theoretically clarified. Furthermore, theoretical law distortion yields, which are decided by the uncontrollable grating phases at cleaved facets, were calculated for devices with various /spl kappa/L values and facet reflectivities, in order to obtain desirable design for the lasers used for subcarrier multiplexing.<<ETX>>

InGaAsP/InP 1.3-&#181;m wavelength surface emitting LED&#769;s for high-speed short-haul optical communication systems

Performance and reliability for InGaAsP/InP 1.3-µm wavelength high-speed surface-emitting DH light emitting diodes (LEDs) have been investigated. High-speed and high-radiance performances were obtained by the optimal design of both structural parameters and LED driving circuit. Rise and fall times were both 350 ps and peak optical power coupled to a 50-µm core 0.20 NA graded-index fiber at the 100-mA pulse current was - 15.8 dBm with 6-dB optical ON/OFF ratio. A 2-Gbit/s non-return-to-zero (NRZ) pulse transmission over a 500-m span was carried out, Feasibility of using surface-emitting LEDs in a high-speed optical communication system has been confirmed. Accelerated aging tests on high-speed LEDs were carried out. The half-power lifetimes have been estimated to be more than 1 × 108h at 50°C ambient temperature.

150 Mbits−1 ch−1 12-channel optical parallel interface using an LED and a PD array

An optical fibre parallel interface has been developed for card-cage to card-cage and board-to-board interconnections, representing a practical and promising optical interconnection. For a system design of a 12 channel, 150 Mbits−1 ch−1 optical parallel interface over a distance of 100 m, it is shown that the choice of a long wavelength LED/PD array with graded index optical fibre array meets the requirements for both power budget and skew limitation over this transmission distance. A 7 mm thick compact package transmitter and receiver module was developed, employing a Zn-doped, mesa structure, 1.3μm LED array and an isolated InGaAs PD array. An optical parallel transmission experiment over 100 m was successfully demonstrated using these modules.

Compact multi-channel LED/PD array modules using new assembly techniques for hundred Mb/s/ch parallel optical transmission

Compact 12-channel LED/PD (light emitting diode/photodiode) array modules using novel assembly techniques have been developed for high-speed parallel optical transmission. Optical and electronic devices were mounted on a lateral point and the common submount surfaces, respectively, for high-speed operation and module package miniaturizing. The flip-chip technique by solder bumps was employed for optical array chip bonding, in order to simplify the chip mounting., A 12-channel 150- Mbit/s/ch 100-m parallel optical transmission with small electronic crosstalk has been demonstrated.<<ETX>>

External optical feedback resistant characteristics in partially-corrugated-waveguide laser diodes

In subcarrier multiplexing (SCM) systems low relative intensity noise (RIN) is essential to realize high carrier-to-noise ratio. However, external optical feedback from the surfaces of other devices, such as the optical connectors used in fiber communication systems, induces operational instability in laser diodes and increases RIN. Partially-corrugated-waveguide laser diodes (PC-LDs) show attractive low intermodulation distortion characteristics due to their uniform electric field. In this paper, external optical feedback resistant characteristics in PC-LDs were analyzed based on the mode-competition theory.

Multiple-wavelength partially corrugated LD array for high-capacity CATV applications

Arrayed low-modulation-distortion laser diodes (LDs) are very attractive light sources for use in high-capacity CATV systems, because their carrier-to-noise ratio (CNR) can be drastically improved by mixing light output launched from each LD separately modulated.1 A 6-dB CNR improvement can be expected theoretically by using a four-channel LD array. However, it is difficult to realize low-distortion LD arrays, because of a poor production yield for low-distortion DFB-LDs, even for a single LD chip. We have developed low-distortion 1.3-μm partially corrugated waveguide laser diodes2,3 (PC-LDs), which realize a marked yield improvement, for use in SCM mobile communication systems. This paper reports newly developed multiple-wavelength PC-LD array for use in high-capacity CATV systems. High-yield performance as well as low-distortion characteristics of the PC-LD array are demonstrated.

150-Mbit/s/ch 12-channel optical parallel transmission using an LED and PD array

High speed optical parallel transmissions are attractive for various computer interface and interconnections because of their advantages in transmission capacity, distance, and small cable size over electrical parallel transmission due to low skew and low signal loss in fibers. Moreover, they have advantages in electrical component cost and size over optical serial transmissions, when the bit rate per channel increases to over 100 Mbit/s, because they do not need faster driver/receiver and MUX/DEMUX circuits. Monolithically integrated linear arrays of low drive current, high speed light emitting diodes (LEDs) are particularly useful because of their potential for low temperature sensitivity, high reliability, and low component cost. However, the high speed linear LED arrays reported1,2 have been requiring large drive current of 100-150 mA/ch for sufficient fiber coupled power and speed. This paper reports a 12-channel 150-Mbit/s/ch 100-m optical parallel transmission, using a newly developed low drive current LED and PD array, with as low as 15-mA p-p/ch LED drive current. This high speed optical parallel transmission should meet the demand for upgrading the performance of high speed channels and interfaces for supercomputers and other systems.

Laser Diodes for Local Access

This paper describes newly developed laser diodes for optical access networks, and technology requirements for total system cost reduction are shown. A High temperature, high efficiency 1.3um strained MQW laser has been developed for passive optical network applications. Novel partially corrugated waveguide structure (PC) laser diodes for hybrid fiber/coax systems are shown. High yield, low intermoduration distortion characteristics were demonstrated theoretically and experimentally. Future perspectives of laser diodes for the local access are also described.