Masaharu Nakaji

Four-channel 25Gbps optical receiver for 100Gbps Ethernet with built-in demultiplexer optics

A compact four-channel 25Gbps receiver with built-in demultiplexer realizes high sensitivity less than −12.1dBm and low cross-talk penalty of less than 0.1dB per channel in 12mm × 17mm × 7mm for the next-generation 100Gbps Ethernet applications.

Recent Advances in AlInsAs Avalanche Photodiodes

We present practical planar AlInAs APDs, which have large gain-bandwidth products, low noise, and high reliability. The APD receivers had a sensitivity of-28.6 dBm at 10 Gb/s and -37.0 dBm at 2.5 Gb/s.

25Gbps × 4ch photodiode array with high responsivity for 100Gbps Ethernet

Four-channel surface-illuminated photodiodes monolithically integrated in one array chip are fabricated for 100Gbps Ethernet. The photodiode with an optimized distributed Bragg reflector has a 3dB bandwidth of 25GHz and the highest responsivity of 0.92A/W at a 1.3µm wavelength.

The development of the 1.27 μm high responsivity AlInAs avalanche photodiodes for 10G-EPON (OLT)

We report the 1.27 μm AlInAs APD with high responsivity of 0.93 A/W and wide bandwidth of 8.3 GHz at a multiplication factor of 10 optimized for 10G-EPON (OLT).

Coaxial high-current photodiode module for analog optical links

We fabricated a coaxial high-current InGaAs/InP p-i-n photodiode module using a small-sized TO-can package with a diameter of 4.8 mm, and demonstrated an RF power output of 25.2 dBm at a frequency of 5 GHz.

Line scanning time-of-flight laser sensor for intelligent transport systems, combining wide field-of-view optics of 30 deg, high scanning speed of 0.9 ms/line, and simple sensor configuration

Abstract. We developed a line scanning time-of-flight (TOF) laser sensor for an intelligent transport system (ITS), which combines wide field-of-view (FOV) receiving optics of 30 deg and a high-speed microelectro mechanical system scanner of 0.9  ms/line with a simple sensor configuration. The newly developed high-aspect ratio photodiode realizes the scanless and wide FOV receiver. The sinusoidal wave intensity modulation method is used for the TOF measurement. This enables the noise reduction of the trans-impedance amplifier by applying the LC-resonant method. The vehicle detection and axle counting, which are the important functions in ITS, are also demonstrated.

Demonstration on range imaging of 256×256 pixels and 30 frames per second using short wavelength infrared pulsed time-of-flight laser sensor with linear array receiver

Abstract. We demonstrated the range imaging with high resolution of 256×256  pixels and high frame rate of 30 frames per second (fps) using a short wavelength infrared pulsed time-of-flight laser sensor, which is suitable for long range imaging. We additionally demonstrated the long range imaging of more than 1 km and wide field of view imaging of 12  deg× 4  deg, 768×256  pixels, and 10 fps. For these demonstrations, we developed the linear array devices of the aluminum indium arsenide avalanche photodiode array and silicon germanium bipolar complementary metal oxide semiconductor read-out integrated circuit array. We also deployed the flattop beam illumination optics with the beam division and recombination method and realized efficient line shape illumination.

Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

Abstract. We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5  μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120  pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.