Sumitomo Electric Industries, Limited

Masaru Takechi

Yasushi Fujimura

Takehiko Kikuchi

Yutaka Moriyama

Yoshihiro Tateiwa

Sousaku Sawada

A bias control method of a nested optical modulator includes detecting a frequency component that has a frequency equal to a frequency of a dither signal and that is included in an output of the optical modulator, with changing a voltage value of a first bias, to measure a first error-detection value, obtaining a first error-detection curve representing a relationship between the first error-detection value and the voltage of the first bias, obtaining a first correction value based on the first error-detection curve, and obtaining the first error-detection value obtained when the first bias voltage value is equal to a voltage value obtained by adding the first correction value to the first bias voltage value at a zero-crossing point of the first error-detection curve, as a first error control value. The first bias is controlled so that the first error-detection value is the first error control value.

Bias control method of optical modulator and optical transmission module

An optical circuit that monolithically integrates a splitter, two optical 90&#xb0; hybrids, and first to fourth waveguides on a unique substrate is disclosed. The splitter splits a local beam into first and second local beams each provided to the hybrids through the third and fourth waveguides, while, the signal beam including first and second signal beams each provided to the hybrids through the first and second waveguides without intersecting with the third and fourth waveguides. The hybrids extract in-phase components and quadrature phase components of the first and second signal beams with respect to the first and second local beams, respectively. The phase statuses of the quadrature components against the in-phase components are same in the two hybrids.

Optical circuit

A technique for measuring an optical coherent receiver is disclosed, where the optical coherent receiver recovers a data by an interference between signal light and local light. The technique includes steps of (i) equalizing optical lengths of the signal light and the local light from the optical source, respectively, and (ii) during a scan of the frequency, maximizing an output of the optical coherent receiver by the feedback control from an output of the optical coherent receive to the phase of the local light. The technique has a feature that, when the feedback control set a delay/lead in the phase of the local light to be 2V&#x3c0;&#x2212;&#x394;, the delay/lead of the phase of the local light is decreased/increased by 2V&#x3c0;, where 2V&#x3c0; corresponds to one period of the wavelength of the local light.

Method of measuring frequency response of optical coherent receiver

An optical receiver comprises a package provided with an input window; a polarization-maintaining optical fiber fixable to the input window; a polarization beam splitter, disposed on the package, for inputting light outputted from the polarization-maintaining optical fiber and outputting first output light and second output light having respective polarization directions different from each other; a beam splitter, disposed on the package, for splitting the first output light; a first light-receiving element, optically coupled to the beam splitter, having two light-receiving parts corresponding to two kinds of the output light split by the beam splitter; and a second light-receiving element, disposed on the package, for receiving the second output light.

Optical receiver and optical axis alignment method thereof

An optical module that implements an MMI device including an optical hybrid primarily made of semiconductor material is disclosed. The MMI device, which has a rectangular plane shape and includes multi-mode couplers, is mounted on a carrier. The carrier provides a step extending in a whole lateral width of a top surface thereof, where the step makes a gap against the MMI device in an area where the MMI couplers are formed.

Optical module having multi-mode coupler formed on semiconductor substrate

An optical receiver for coherent optical communication, includes: a splitting element that splits a signal light into two optical axes; optical hybrids each of which is coupled with the two split optical axes; a skew adjustment element that is arranged on one of the optical axes, and adjusts a difference between optical path lengths of the two optical axes between the splitting element and the optical hybrids; a carrier; an adhesive that is filled between the skew adjustment element and the carrier; and a void that is located at an end portion of an optical axis direction of the skew adjustment element in a region where the skew adjustment element and the carrier are opposed to each other, the void being not filled up with the adhesive.

Optical receiver and method for manufacturing the same

An optical receiver device including: a light-receiving element having a first electrode acting as an outputting electrode and a second electrode coupled to a potential that is different from a ground potential; an amplifier device having an amplifier element, a connection terminal including a signal electrode and a ground electrode on an upper face thereof; a first conductor coupling a potential of the first electrode of the light-receiving element to the signal electrode, the first conductor being introduced from the upper face side of the amplifier device; and a second conductor coupling a potential of the second electrode of the light-receiving element to the ground electrode, the second conductor introduced from the upper face side of the amplifier device.

Growing community of inventors

Yokohama, Japan

Masaru Takechi