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We have developed a flip-chip interconnection technique to solve the problem of the degradation of the modulation bandwidth of an optical transmitter due to the parasitic inductance of bonding wire. And we have fabricated an LE-EA-DFB laser module that has a 3-dB bandwidth of 59 GHz thanks to our flip-chip interconnection technique. The fabricated optical receiver, which includes a wideband electrical amplifier, has a 3-dB bandwidth of 51 GHz. Using these optical modules with a 3-dB bandwidth of more than 50 GHz, we have obtained a bit-error rate of less than 2 × 10−4, which is an error-free condition using KP4 forward error correction, under 53.2-Gbaud 4-level pulse amplitude modulation (4-PAM) operation without an equalizer even after a 2-km transmission through single-mode fiber.

Uni-traveling-carrier (UTC) photomixers and Schottky barrier diodes (SBDs) are described for continuous THz-wave generation and detection, respectively. A newly designed narrowband UTC photomixer based on a bowtie antenna was found to have a resonance feature with enhanced THz output at 0.5 THz. Quasi-optical packaging was used to fabricate an SBD detector with 1080 V/W sensitivity at 250 GHz, the highest yet reported for InP-based quasi-optical broadband SBD modules.

We demonstrate the first 4 × 28 Gbaud PAM4 data reception with an integrated APD-ROSA. A minimum receiver sensitivity of ™21.2dBm OMA of the inner-eye was obtained, which enable us to achieve 30-km transmission, assuming a SSMF.

This talk reviews our work with avalanche photodiodes (APDs) with unique vertical-illumination structure. The APD features 3-dB bandwidth of 18.5 GHz with multiplied responsivity of 9.1 A/W, satisfying requirements for 100-Gb/s systems. Further high-speed characteristics targeting 50-Gb/s are also discussed.

We achieved a high-performance InAlAs avalanche photodiode (APD) for beyond 25-Gbit/s applications, such as 50-Gbit/s. The large optical tolerance of the APD's vertical-illumination structure makes optical coupling easy compared with waveguide-type structures. The fabricated APD exhibits responsivity of 0.69 A/W with a large 3-dB bandwidth of 30 GHz at a multiplication factor (M) of 4.6, which enables 50-Gbit/s highly sensitive operation.

This work investigated the field confinement behavior and junction size scaling for an inverted p-down avalanche photodiode, which requires no selective diffusion or ion-implantation and regrowth techniques. With this structure, the small spread of electric field of only 1 µm is obtained. The maximum 3-dB bandwidth of 23 GHz at the multiplication factor of 4.5 is obtained with the diameter of 20 µm, with responsivity as high as 0.91 A/W. These results indicate that the structure is favorable for high-speed and high-sensitivity operation.

This paper describes device and integration technologies for 100-Gbit/s polarization division multiplexed quadrature phase shift keying integrated coherent receiver front-end. The silica-based planar lightwave circuits for the optical passive circuits, InP-based photodiode for the opto-electrical conversion, and InP HBT for the transimpedance amplification are used to achieve high-performance. A module-level hybrid integration technology based on a chip-scale packaged O/E converter is applied as the integration technology. The fabricated receiver front-end has a wide dynamic range of around 20dB with a constant local power of 13.5 dBm and an excellent common-mode rejection ratio of better than -25dB up to 25GHz.

We present a terahertz wave wireless link operating at 300 GHz which has a potential for use in ultra fast future wireless services in short range. Terahertz wave was generated and modulated with photonic technologies in the transmitter, allowing us to use radio on fiber system concept as well. For the receiver, we used a Schottky barrier diode detector integrated with a planar antenna. With the link, error free data transmission at 12.5 Gbps was experimentally demonstrated. Taking the performance margin of the transmitter and receiver into consideration, we believe that even up to 20-Gbps data can be transmitted.

We fabricated a 40-Gbit/s CAN-type ROSA using a maximized-induced-current photodiode (MIC-PD). 40-Gbit/s error-free operation was achieved for the first time with a CAN-type ROSA, owing to the high-speed capability of the MIC-PD and impedance matching of glass feedthrough.

Spectroscopic images were obtained using a system combining a tunable continuous-wave terahertz laser with an InP-based Schottky barrier diode detector integrating a broadband log-periodic antenna. The distribution of polymorphic forms in pharmaceutical tablets was observed in obtained at images over 1 THz.

We fabricated 25-Gbit/s receiver optical subassemblies (ROSAs) using a maximized-induced-current photodiode (MIC-PD). By employing a high-speed and high-responsivity MIC-PD, we achieved successful operation at 25 Gbit/s using a flexible printed circuit board and a coaxial package designed for a 10-Gbit/s ROSA.

A novel maximized-induced-current-photodiode (MIC-PD) structure with a composite field depletion layer achieves high responsivity of 0.8 A/W and a wide 3-dB bandwidth of 30 GHz at a low reverse bias voltage of 2 V for optical input power of +7 dBm.

A high-output-power photomixer module operating at 200-500 GHz has been developed. The module consists of a uni-traveling-carrier photodiode, a PD-waveguide mode-conversion coupler, and a compact metal package with a rectangular-waveguide that outputs sub-terahertz wave. The fabricated module exhibits a 10- dB down bandwidth of about 300 GHz and an output power as high as -2.7 dBm at 350 GHz. This is the highest value ever reported for a photomixer module operating at 350-GHz band.

We have developed a single-package 2ch-balanced receiver module composed of a monolithically integrated 4-PDs and a 2ch-IC. The module has excellent receiver characteristics and is suitable for 43-Gbit/s DQPSK.

A novel photodiode, PD, named uni-traveling-carrier photodiode (UTC-PD) is developed, which has both high-speed and high output current capabilities. In this paper, recent progress in UTC-PD technologies and applications for communications, measurements, and sensing is described

This paper presents a compact waveguide-output UTC-PD module that integrates a UTC-PD and a HEMT pre-amplifier (PD-amp module), which is suitable for practical applications. A transmission experiment of 10 Gbit/s signal is also shown to demonstrate the feasibility of the fabricated module.

In this paper, we report the development of a uni-traveling-carrier photodiode module having a 1-mm connector as an electrical output port. The module design and fabrication is developed. Thus UTC-PD with a 1-mm connector output port has a 3-dB bandwidth of 80 GHz at an average photocurrent of 10 mA with a responsivity of 0.35 A/W. These results lead to conclude that the fabricated module is promising for practical use in high-bit-rate optical communication systems.

We propose a remote base station using a uni-traveling-carrier waveguide photodiode without a millimeter-wave amplifier. By using this setup that yields 0-dBm RF output at 40 GHz, error-free wireless transmission is confirmed after 20-km fiber propagation.

A novel waveguide photodiode is proposed. This photodiode uses uni-traveling-carrier structure which makes it possible to simultaneously achieve high output voltage and high speed. With a 50-/spl Omega/ load, the photodiode having an external quantum efficiency of 32% yields an output voltage of 1.3 V with a bandwidth of 55 GHz and 0.45 V with a bandwidth of 70 GHz.

The reliability of InP/InGaAs uni-traveling-carrier photodiodes has been studied. A failure rate of 42 FIT at 25 C was obtained from long-term bias-temperature tests. Stable operations for over 2000 h were also confirmed under high optical input conditions.

A K- to Ka-band photonic microwave generator (PMG) consisting of a uni-traveling carrier photodiode (UTC-PD) and a monolithically integrated bias circuit utilizing a 1/4-wavelength coplanar waveguide is presented. The device exhibits a high saturation-output-power of +14 dBm at 26 GHz for a bias voltage of -4 V. The output power is almost constant within a frequency range from 23 to 29 GHz. The 3-dB down bandwidth of the generator is as wide as 20 GHz, which is in good agreement with the circuit model calculation. Two types of device, one with and without a DC-cut capacitor, exhibit almost the same input-output characteristics. The PMG is a suitable device for the broadband high-output fiber-radio applications.

A uni-traveling-carrier refracting-facet photodiode, a short-stub bias circuit, and a patch antenna were monolithically integrated to make a compact and low-cost millimeter-wave photonic emitter for fiber-radio applications. The device emits the maximum effective radiation power of 17/spl plusmn/3 dBm at 60 GHz.

Summary form only given. In summary, we demonstrated high-speed hybrid-receiver module using a photonic lightwave circuit (PLC) platform and monolithically integrated photoreceiver array. This is the first demonstration of a silica based PLC platform that can operate at 10 Gbit/s. This technology will be applicable to high-speed optoelectronic components that will offer both optical and electronic signal processing.