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Photonic delay-based reservoircomputers (RC) have emerged as an attractive high-speed, low-power alternative to traditional digital hardware for AI. We demonstrate experimentally a novel hybrid RC scheme in which input data is first preprocessed through several convolutional layers, either trained or untrained, digitally to generate novel feature maps. These random feature maps are then processed through an optoelectronic implementation of delay-based RC. Using the MNIST dataset of handwritten digits, experiments of our proposed hybrid scheme achieve classification error of 1.6% using untrained convolutions, and an error of 1.1% using trained convolutions, results comparable to that of state-of-the-art machine learning algorithms. Additionally, our experimental implementation can offer a potential 10× decrease in model training time, compared to that of common digital alternatives. [ABSTRACT FROM AUTHOR]

We have developed a 1.55-μm 40 Gbps electro-absorption modulator laser (EML)-based transmitter optical subassembly (TOSA) using a novel flexible printed circuit (FPC). The return loss at the junctions of the printed circuit board and the FPC, and of the FPC and the ceramic feedthrough connection was held better than 20 dB at up to 40 GHz by a newly developed three-layer FPC. The TOSA was fabricated and demonstrated a mask margin of >16% and a path penalty of <;0.63 dB for a 43 Gbps signal after 2.4-km SMF transmission over the entire case temperature range from -5° to 80 °C, demonstrating compliance with ITU-T G.693. These results are comparable to coaxial connector type EML modules. This TOSA is expected to be a strong candidate for 40 Gbps EML modules with excellent operating characteristics, economy, and a small footprint. [ABSTRACT FROM PUBLISHER]

We discuss the wafer design and fabrication process for the 1.3-μm-wavelength AlGaInAs/InP transistor lasers, and the structural dependence of lasing and the electrical characteristics are shown. We particularly focus on the base structure, and the thickness and width dependence are numerically and experimentally analyzed. A thicker base layer resulted in lower optical confinement factor in the quantum wells (QWs), higher optical loss, and lower current gain. In addition, a wider base width caused leak current recombination outside the QWs. By modifying the structure of an n-p-n TL, it was possible to simultaneously realize room-temperature continuous-wave lasing and transistor operation. [ABSTRACT FROM PUBLISHER]

Small- and large-signal analyses of transistor lasers (TLs) are demonstrated for 0.98-\mum wavelength GaInAs/GaAs and 1.3-\mum AlGaInAs/InP systems. The modulation bandwidth of the TL was larger than that of a laser diode due to the lower damping effect in the former. Comparisons between TLs with different numbers of quantum wells indicated that a large signal response and high modulation bandwidth could be realized simultaneously. However, in the case of large-signal analysis, the calculated eye diagrams were degraded by a resonance oscillation peak. By changing structural parameters such as the facet reflectivity and by controlling the damping effect, the resonance frequency peak was suppressed and clear eye diagrams of >40~Gb/s were obtained. [ABSTRACT FROM PUBLISHER]

Room-temperature continuous-wave operation of a 1.3-\mum npn-AlGaInAs/InP transistor laser is successfully achieved for the first time. A threshold current of 39 mA and an external differential quantum efficiency of 13% are obtained under common base operation, while simultaneous transistor action is achieved with a current gain \beta of 0.02. [ABSTRACT FROM PUBLISHER]