Nippon Telegraph and Telephone Corporation

Shibuya Computer Service Kabushiki Kaisha

Shigeru Kanazawa

Josuke Ozaki

Hiromasa Tanobe

Takahiko Shindo

Meishin Chin

Yuta Ueda

Hiroyuki Ishii

Naoki Fujiwara

Koji Takeda

Kota Shikama

Takushi Kazama

Atsushi Kanda

Nobuhiro Kikuchi

Yoshihiro Ogiso

Shinsuke Nakano

Toshihide Yoshimatsu

Hitoshi Wakita

Yasuhiko Nakanishi

Shigetsuyo Hasuo

Takamitsu Kadokura

Teruo Kenmochi

A highly efficient optical burst transmitter is provided. An embodiment is an optical burst transmitter including a control circuit configured to output a data signal and a burst control signal and a semiconductor optical amplifier configured to output an optical data signal modulated using the data signal as an optical burst data signal controlled using the burst control signal, the optical burst transmitter including: an electric line configured to connect the control circuit and the semiconductor optical amplifier and transmit the burst control signal; and an impedance matching circuit configured to impedance-match a characteristic impedance of the electric line and the semiconductor optical amplifier with each other.

Optical burst transmitter

An optical semiconductor chip of the present disclosure includes a high frequency line between an electrode pad receiving a modulation signal and a modulation electrode on the optical waveguide having a light absorption layer. The depletion layer capacitance generated in the light absorption layer is canceled by an inductor component of the high frequency line. When a portion directly below the high frequency line is embedded with a low-dielectric-constant material or is made hollow, the parasitic capacitance is further reduced. The high frequency line may have a zigzag shape as well as a linear shape. The electrode pad on the optical semiconductor chip can be connected to other substrates including RF lines for modulation signal input by bumps or wire bonding.

Optical semiconductor chip

In the present disclosure, in an EADFB laser in which an SOA has been integrated, a new configuration in which a problem of deterioration of optical waveform quality and insufficient optical output is solved or mitigated while taking advantage of characteristics that the same layer structure can be used and a manufacturing process can be simplified is shown. In an optical transmitter of the present disclosure, a waveguide structure having different core widths (waveguide widths) is adopted while using the same layer structure for a DFB laser and the SOA. Waveguides with different core widths are adopted so that a problem of insufficient saturated optical output or waveform deterioration due to a pattern effect is solved and mitigated. A passive waveguide region having a tapered shape is introduced in a part between an EA modulator and the SOA so that a waveguide width is continuously changed.

Optical transmitter

Provided is a semiconductor light source element or an optical device including a semiconductor optical waveguide of a high-mesa semi-insulated embedded structure having a window structure made of the same material as an overclad layer at a light emission end, and a method for manufacturing thereof, in which an active layer at a portion of the window structure is removed, and then the same layer as the overclad layer is formed.

Method for manufacturing optical semiconductor waveguide window structure

In an EADFB laser with an integrated SOA, a new configuration in which deterioration of optical waveform quality is solved or mitigated while taking advantage of characteristics that the same layer structure can be used and the manufacturing process can be simplified is shown. In an optical transmitter of the present disclosure, a carrier density is optimized depending on a light intensity inside the SOA and an amount of carrier consumption. The SOA is electrically separated into a plurality of regions, and a current is injected into each region independently. The divided SOA region is configured so that a length of the SOA region becomes shorter as a region is farther from an incidence end of the SOA. Further, for the divided SOA, an amount of carrier consumption increases as the SOA region is farther from the incidence end, so that a current injection amount is increased.

Phase modulation electrode lines of a semiconductor Mach-Zehnder optical modulator are formed along waveguides. Output-side lead lines are bent in a direction crossing the extending direction of the waveguides in the plane of a dielectric layer and are connected to terminal resistors. The output-side lead lines are formed in a predetermined width corresponding to a desired impedance and make the width narrower than the predetermined width only in the bent portions and portions where the output-side lead lines crosses the waveguides.

Semiconductor Mach-Zehnder optical modulator and IQ modulator

In a terminator, a midpoint electrode is provided between a first signal electrode and a second signal electrode, a first resistor is connected between the first signal electrode and the midpoint electrode, a second resistor is connected between the second signal electrode and the midpoint electrode, a first GND electrode is provided on a side opposite to the side where the first resistor is provided with the first signal electrode interposed therebetween, a second GND electrode is provided on the side opposite to the side where the second resistor is provided with the second signal electrode interposed therebetween, and capacitances in the terminator are formed between the first signal electrode and the midpoint electrode, between the second signal electrode and the midpoint electrode, between the first signal electrode and the first GND electrode, and between the second signal electrode and the second GND electrode.

Optical modulator module

A semiconductor Mach-Zehnder optical modulator includes input side lead-out lines, phase modulation electrode lines, output side lead-out lines, electrodes that apply modulation signals propagating through the phase modulation electrode lines to respective waveguides, and ground lines. Furthermore, at least one n-type semiconductor layer or p-type semiconductor layer is formed between a substrate and a dielectric layer in a lower layer under the output side lead-out lines intermittently along the output side lead-out lines.

Semiconductor Mach Zehnder optical modulator

There is provided a highly convenient package for an optical module in which a device can be mounted as it is even when the number and mounting position thereof are different according to the device to be mounted. The package includes a base plate having a top surface on which devices are assembled, an optical fiber mounting component mounted on the top surface of the base plate, a direct current electrical interface component and a high frequency electrical interface component mounted on the top surface of the base plate. The optical fiber mounting component and the electrical interface components are separately manufactured, separately assembled on the top surface of the base plate, and fixed in different modes. The optical fiber mounting component is fixed by fastening with screws and fixed by soldering, and the electrical interface components are fixed by fastening with the screw.

Package for optical module

Reflection between a Mach-Zehnder modulator and a termination resistor is suppressed. An optical modulator includes a differential drive open collector driver IC, a differential drive semiconductor Mach-Zehnder modulator, and a differential terminator. The Mach-Zehnder modulator includes waveguides and a differential high-frequency line. The differential terminator includes a differential high-frequency line and termination resistors. The differential high-frequency line includes a capacity provided at least one of between signal lines and between a signal line and a ground line.

Optical modulator

There is provided an optical element mounted on a substrate and an optical coupling element mounted on the substrate. The optical coupling element includes a guide unit extending in a direction parallel to a plane of the substrate so as to fix an optical fiber. There is provided a mold resin layer formed on the substrate so as to cover the optical element and expose a side surface of the optical coupling element at one end of the guide unit. The optical element includes a light incidence/emission unit on a side surface perpendicular to the plane of the substrate, and the other end of the guide unit and the light incidence/emission unit are disposed to face each other.

Optical component and method for manufacturing same

A second substrate is formed on a first substrate. The second substrate includes a Mach-Zehnder modulation unit and a coplanar line. Further, the second substrate is formed on and bonded to the first substrate via an adhesive layer made of a non-conductive adhesive. The Mach-Zehnder modulation unit has an optical modulation region by an electro-optic effect. The coplanar line transmits a modulated signal to the optical modulation region.

Mach-Zehnder modulator

A high-frequency transmission line is provided that improves a high-frequency characteristic. The high-frequency transmission line includes a first conductor line, a termination resistance connected to the first conductor line, a second conductor line connected to the termination resistance, and a ground line that is provided to be opposed to the first conductor line, the termination resistance, and the second conductor line to have a predetermined distance thereto and that is connected to the second conductor line. The first conductor line and the ground line are formed to have a line width decreasing toward the termination resistance, respectively.

High-frequency transmission line and optical circuit

A card sorting apparatus includes at least two card stackers, a sensor for reading characters, symbols and the like attached to the cards, a card rack for holding a plurality of cards, and a memory for storing information indicative of the cards held by the card rack. The card rack is connected to at least one of the card stackers accommodating cards. A predetermined number of cards are first transferred to the card rack and a comparison is performed between a group of cards in the card rack and cards transferred to the card rack next. Cards satisfying comparison conditions are fed into either of the card stackers and cards are sorted in advance between the card rack and card stacker. Also provided is a card sorting rack for the sorting apparatus, the rack having a plurality of card supporting members for supporting cards, and a moving member for selectively moving at least one of the card supporting members to extract the corresponding card.

Growing community of inventors

Tokyo, Japan

Shigeru Kanazawa