S. Kaneko

An electroabsorption modulator module for digital and analog applications

This paper presents an electroabsorption modulator (EAM) module for digital and analog (D/A) applications. Optically broad-band operation of the EAM module is studied for such digital application as wavelength division multiplexing (WDM) systems. Utilizing anisotropic electroabsorption of a multiple quantum-well (MQW) EAM, 40- and 100-nm bandwidth operations in 2.5-Gb/s digital signal transmission over 200-km standard fiber are confirmed by the experiments and the simulations, respectively. For analog applications, low distortion and high link gain characteristics of the EAM module are investigated at the wavelength of 1535 nm. High spurious-free dynamic range of 123 dB/spl middot/Hz/sup 4/5/ and high link gains of -10.3 dB with matching circuit and -20.6 dB without matching circuit are obtained using the EAM module.

Novel fiber alignment method using a partially-metal-coated fiber in a silicon V-groove

We propose a novel fiber alignment method using a partially metal-coated (PMC) fiber. A PMC fiber is a fiber whose side is partially metal coated, and a core of PMC fiber can be regarded as eccentric with respect to the outside of PMC fiber. Rotating the PMC fiber in a silicon V-groove, the core position can be aligned. Using this method, laser diode modules with high coupling efficiency were obtained.

1.3-/spl mu/m uncooled DFB laser-diode module with a coupled differential feed for 10-Gb/s ethernet applications

A coaxial 10-Gb/s 1.3-/spl mu/m distributed feedback (DFB) laser-diode module with a coupled differential feed has been developed. The differential cascaded feed with the characteristic impedance of 100 /spl Omega/, which consists of a 140-/spl Omega/ ground-signal-signal-ground (GSSG) leads, a small-sized 60-/spl Omega/ feed-through, and a 140-/spl Omega/ wire-bonding pad, provides less sensitivity to the lead length. Integrating with 25-/spl Omega/ matching resistances and a 60-/spl Omega/ differential microstrip line, whose length corresponds to one eighth of wavelength at 7 GHz, gives wide-band impedance matching between the feed and the laser diode portion with small power loss. Experiment shows good return loss of greater than 9 dB at 10 GHz, and small change of bit error rate (BER) up to the lead length of 4 mm. With a newly developed 250-/spl mu/m cavity laser chip, we have demonstrated stable eye diagrams with the mask margins of 31 and 29% at case temperature of 0 and 85/spl deg/C, respectively.

Impact of package resonance on eye diagram in high-speed optical modules

We analyze the impact of package resonance on the eye diagram by numerical simulations using the coupled-mode theory. Dependence of the impact on resonant frequency and number of resonance are also discussed.

Low-crosstalk hybrid-integrated optical transceiver module using a polymer PLC chip and a MMF stub

We report a hybrid-integrated optical transceiver module using a discrete polymer planar lightwave circuit (PLC) chip and a multimode fiber (MMF) stub, A low-crosstalk performance is indispensable for this transceiver module to achieve a good receiver (Rx) performance under the full duplex operation. The discrete polymer PLC chip and the MMF stub well isolate a Rx from a transmitter both optically and electrically, and excellent receiver performance of 0.1-dB power penalty caused by the crosstalk is obtained.

Photodiode Packaging Technique Using Ball Lens and Offset Parabolic Mirror

In this paper, we demonstrated the use of a photodiode (PD) packaging technique that employs a catadioptric system. This optical system consisted of two components: a BK7 ball lens with a diameter of 1.5 mm that was soldered with glass on a hermetic cap and a plastic-molded offset parabolic mirror with a radius of 550 mu m and an offset of 550 mu m. The offset parabolic mirror was mounted above a surface-illuminated InGaAs pin PD with a detective area of diameter 20 mum. When an incident pencil of rays were passed through the ball lens and then perpendicularly reflected by the mirror and impinged upon the PD, compact planar assembling became possible for numerous electrical parts on a can-type header for minimizing parasitic impedance due to wire bonds. The optical system provided a high coupling efficiency of 98% between a single-mode fiber and the PD.

A compensation method for dispersion-induced third-order intermodulation distortion using an etalon

A method to compensate dispersion-induced third-order intermodulation distortion (IM3/sub CD/) in subcarrier multiplexing (SCM) optical transmission systems is proposed. It is confirmed theoretically and experimentally that IM3/sub CD/ can be compensated by interference-induced third-order intermodulation distortion (IM3/sub IN/). Simple analytic expressions of IM3/sub CD/ and IM3/sub IN/ are derived from the same expression of optical electric field which includes exact phase term taking into account the phase of laser chirp. From the theoretical analyses, we clarified the conditions of IM3/sub CD/-compensation. IM3/sub IN/ can be easily generated by an etalon which is a kind of interferometer and a optical glass plate. More than 30 dB of IM3/sub CD/-compensation was achieved, and IM3/sub CD/-compensation was achieved regardless of the transmission distance by adjusting tilt angle of the etalon. Using this method, high quality signal transmission can be realized even though the wavelength of laser diode (LD) is not coincident with the fiber zero dispersion wavelength.

High-speed electroabsorption (EA) modulator modules using the flip-chip bonding (FCB) technique

We developed EA-modulator modules with over 40-GHz modulation bandwidth using the flip-chip bonding (FCB) technique. The FCB minimizes parasitic inductance and module-to-module variation in electrical characteristics, and is indispensable to high-speed EA-modulator modules for 80 Gbit/s.

Micromechanical optical switch using retroreflector-based optical system

We propose a retroreflector-based optical system using a fiber collimator array, which extremely simplifies fabrication processes and offers low coupling loss of 0.29 dB. We also demonstrate 2/spl times/2 micromechanical optical switch module employing the optical system.

Retroreflector-based optical system for easily fabricable 2/spl times/2 micromechanical optical switch modules

We propose the retroreflector-based optical system using the fiber collimator array, which extremely simplifies fabrication processed and offers low coupling loss of 0.29 dB. We also demonstrate 2/spl times/2 micromechanical optical switch module employing the optical system.