Abstract: A functional optical device is disclosed. The functional optical device integrates a coupling unit, a waveguide photodiode (PD) and an optical waveguide on a semiconductor substrate. The coupling unit extracts an optical signal by performing interference of signal light with local light. The optical waveguide carries the optical signal from the coupling unit to the waveguide PD. The semiconductor substrate provides a heavily doped conducting layer and a buffer layer that is un-doped or lightly doped with n-type impurities by density smaller than density of impurities in the heavily doped conducting layer. The conducting layer and the buffer layer continuously and evenly extend from the optical waveguide to the waveguide PD.

Abstract: A functional optical device is disclosed. The optical functional device integrates a coupling unit, a light-receiving element and an optical waveguide on a semiconductor substrate. The coupling unit extracts an optical signal by interfering between signal light and local light. The optical waveguide carries the optical signal from the coupling unit to the light-receiving element. The light-receiving element receives the optical signal. The semiconductor substrate provides a heavily doped conducting layer and a buffer layer that is un-doped or lightly doped with impurities by density smaller than density of impurities in the conducting layer. The conducting layer and the buffer layer continuously and evenly expand from the optical waveguide to the light-receiving element.

Abstract: A functional optical device applicable to a coherent optical communication system as a front end device is disclosed. The functional optical device includes a pair of light-receiving elements of a type of waveguide photodiode (PD), a pair of signal pads, a pair of ground pads, a bias pad, and a substrate that monolithically integrates those elements thereon. The light-receiving elements generate a photocurrent complementary to each other in respective anodes thereof; while, receive biases through the bias pad common to the light-receiving elements. Those pads are disposed along an edge of the substrate such that the signal pads put the bias pads therebetween, and the ground pads put the signal pads and the bias pad therebetween.

Abstract: A radar apparatus configured to prevent a harmonic generated by a limiter from being transmitted outside is provided. The radar apparatus includes a harmonic processor between a circulator and a limiter. The harmonic processor includes harmonic processing stubs, and a compensation stub. The harmonic processing stubs attenuate the harmonic which is generated when the limiter attenuates a transmission signal passed through the circulator. The compensation stub cancels a change of a susceptance caused by disposing the harmonic processing stubs.

Abstract: A pulse compression radar for performing pre-distortion is provided, which has a configuration simplified in circuit structure. A radar apparatus (pulse compression radar) includes an antenna configured to externally transmit a transmission signal transmitted by a power amplifier and receive a reflection signal caused thereby as a reception signal. The radar apparatus includes a reception circuit configured to propagate this reception signal to a radar image creating module. The radar apparatus corrects beforehand, by utilizing the transmission signal (feedback signal) transmitted from the power amplifier, a transmission signal to be inputted into the power amplifier so as to cancel distortion of the transmission signal caused by amplification effect of the power amplifier. Further, a circuit where the reception signal passes and a circuit where the feedback signal passes share a part of each other.

Abstract: A radar apparatus configured to prevent a harmonic generated by a limiter from being transmitted outside is provided. The radar apparatus includes a harmonic processor between a circulator and a limiter. The harmonic processor includes harmonic processing stubs , and a compensation stub. The harmonic processing stubs attenuate the harmonic which is generated when the limiter attenuates a transmission signal passed through the circulator. The compensation stub cancels a change of a susceptance caused by disposing the harmonic processing stubs.

Abstract: A pulse compression radar for performing pre-distortion is provided, which has a configuration simplified in circuit structure. A radar apparatus (pulse compression radar) includes an antenna configured to externally transmit a transmission signal transmitted by a power amplifier and receive a reflection signal caused thereby as a reception signal. The radar apparatus includes a reception circuit configured to propagate this reception signal to a radar image creating module. The radar apparatus corrects beforehand, by utilizing the transmission signal (feedback signal) transmitted from the power amplifier, a transmission signal to be inputted into the power amplifier so as to cancel distortion of the transmission signal caused by amplification effect of the power amplifier. Further, a circuit where the reception signal passes and a circuit where the feedback signal passes share a part of each other.