Naoyuki Yamabayashi

Eight-channel wavelength multiplexing with 200-GHz spacing using uncooled coaxial fiber Bragg grating external-cavity semiconductor laser module

As a low-cost light source for wavelength-division-multiplexing networks, the authors develop an uncooled coaxial fiber Bragg grating external-cavity semiconductor laser (FGL). To realize high-wavelength stability, an FGL structure is adopted, and to reduce the cost of light source itself, a coaxial pigtail module structure is selected. High-wavelength stabilities of 2 pm/mA and 12 pm/K against current and ambient temperature variation are realized. Using the FGLs, successive eight-channel wavelength multiplexing with 200-GHz spacing and with almost the same peak power is realized between -30/spl deg/C to 70/spl deg/C. For each channel, the wavelength difference from the corresponding ITU grid is only within /spl plusmn/0.1 nm at 25/spl deg/C.

Characterization and theoretical analysis of second-order intermodulation distortion of InGaAs/InP p-i-n photodiode modules for fiber-optic CATV

InGaAs/InP p-i-n photodiode (PD) modules for fiber-optic analog CATV have been developed. The optical configuration was optimized by making use of a spherical lens aberration. Responsivity and second-order intermodulation distortion (IMD2) were 0.95 A/W and -85 dBc at V/sub r/=12 V, P/sub in/=0 dBm, and m=40%, respectively. The improvement of IMD2 by defocusing was explained by the decrease of incident optical power density calculated by ray tracing. IMD2 was quantitatively explained through the reverse voltage dependence of responsivity which originates from the variation of the p/sup +/-InGaAs depletion layer thickness.

A coaxial-type 1.3/1.55 /spl mu/m WDM-PD module for optical access networks

A new 1.3/1.55 /spl mu/m WDM/photodiode(PD) module has been designed and fabricated for use in optical access networks. A 1.3 /spl mu/m-PD and a 1.55 /spl mu/m-PD were arranged in series along the optical axis in a coaxial package. The 1.3 /spl mu/m-PD with an In/sub 0.66/Ga/sub 0.34/As/sub 0.76/P/sub 0.24/ photosensitive layer (/spl lambda//sub g/=1.42 /spl mu/m) absorbs 1.3 /spl mu/m digital optical signals and it is transparent to 1.55 /spl mu/m wavelength. The 1.55 /spl mu/m-PD with an In/sub 0.53/Ga/sub 0.47/As photosensitive layer absorbs 1.55 /spl mu/m analog optical signals. Responsivity of the module is 0.82 A/W at 1.31 /spl mu/m wavelength and 0.75 A/W at 1.55 /spl mu/m wavelength, respectively. IMD2 of the 1.55 /spl mu/m-PD measured by two-tone method was -76.1 dBc at Pf(1.55 /spl mu/m) of -6 dBm. Bit error rate (BER) of the 1.3 /spl mu/m-PD was measured at 28.8 Mb/s by using an amplifier with bandwidth of 200 MHz and was found to be less than 10/sup -8/ at Pf(1.3 /spl mu/m) of -30 dBm.

Optical WDM transceiver module using wavelength-selective coupler and WDM-PD for optical access networks

We have proposed a new WDM-transceiver module using a wavelength-selective coupler and a 1.3 /spl mu/m InGaAs WDM p-i-n photodiode and InGaAsP MQW laser diode in order to reduce component number and module size. In this report, we confirmed the fundamental operation of this module assembled with pigtailed components. Evaluation results imply that this WDM transceiver module is promising for application to an optical WDM transceiver/receiver.

3.5-mm-square InGaAs p-i-n photodiodes and their application to optical-axis arrangement between 1.3-/spl mu/m laser diodes and a SMF

InGaAs p-i-n photodiodes (PD) with 3.5-mm/spl times/3.5-mm-large photosensitive area have been fabricated using chlorine-vapor-phase-epitaxial (C-VPE) growth. They showed high responsivity of 0.95 A/W (/spl lambda/=1.3 /spl mu/m) and 1.2 A/W (/spl lambda/=1.55 /spl mu/m) and good homogeneity in the whole area. Long-term reliability was confirmed through high-temperature aging tests at 150/spl deg/C up to 5200 hours. A PD with two pairs of parallel electrodes (PE-PD) was applied to optical-axis arrangement between 1.3-/spl mu/m laser diodes (LDs) and a single mode fibre (SMF). The beam position of a LD was detected in error within /spl plusmn/20 /spl mu/m using PE-PD prior to coupling of a LD beam into a SMF. Total inspection time was reduced to one third the original time.

Miniaturized 300Mb/s optical transmitter/receiver modules using 1.31µm LED and PIN-photodiode

Employing a well-designed 1.3µm source-detector pair of InGaAsP surface emitting LED and InGaAs PIN-photodiode, we have developed a miniaturized optical data link for 300Mb/s transmission. The transmitter and receiver were packaged compactly by the use of hybrid IC technology and newly developed Si integrated circuits. In order to make the most of fiber bandwidth, the peak emission wavelength of LED was designed to be around 1310nm, and 300Mb/s transmission experiment was achieved over 5km with a margin of 6dB.