Sumitomo Electric Industries, Limited

National Institute of Advanced Industrial Science and Technology

Sony Corporation

Katsumi Uesaka

Keiji Tanaka

Haruhiko Kuwatsuka

Kazuhiro Yamaji

Eiichi Banno

Shu Namiki

Hiroyuki Matsuura

Ken Tanizawa

Hajime Shoji

Satoshi Takahashi

Hideki Yoshida

Tohru Watanabe

Manabu Shiozaki

Tomoya Saeki

Daisuke Murakami

Mitsuaki Nishie

Yutaka Onishi

Akihiro Moto

Isao Matsumoto

Naoki Nishiyama

Kuniaki Ishihara

Morihiro Seki

Tomoko Miura

Aaron Albores-Mejia

Yutaka Oonishi

Kenji Kibayashi

Disclosed is an optical device including a first lens and a second lens. The first lens of the optical device is joined to an end surface of an optical waveguide of an optical element to emit light emitted from the optical element. The second lens is optically coupled with the first lens to convert the light emitted from the first lens into collimated light.

Optical device

A wavelength-tunable light source includes a wavelength-tunable laser including a first region and a second region each of which includes at least one of heaters, a frequency locker configured to receive output light of the wavelength-tunable laser and output two electric control signals whose phases are mutually different by 90&#xb0; and having frequency period with respect to frequency of the output light, a thermal electric cooler on which the wavelength-tunable laser and the frequency locker are mounted, and a controller configured to control temperature of the heaters, and the thermal electric cooler on the basis of any one of the two electric control signals.

Wavelength-tunable light source and wavelength control method for the same

An optical transmitter that includes a wavelength tunable laser diode (LD) with a narrowed emission linewidth is disclosed. The optical transmitter further includes a feedback unit and an optical attenuator. The feedback unit, receiving a portion of laser light of the wavelength tunable LD, generates feedback light by rotating the polarization of the laser light by 90&#xb1;5&#xb0;, and returns thus generated feedback light in the wavelength tunable LD. The optical attenuator adjusts power of the feedback light to reduce a line wide of the laser light, or frequency noises thereof.

Optical transmitter implementing wavelength tunable diode

An optical transmitter that narrows the linewidth of its output light is disclosed. The optical transmitter includes a wavelength tunable laser diode (LD) known as a CSG-DR LD integrated with a semiconductor optical amplifier (SOA) driven in a constant magnitude mode. The wavelength of the light output from the LD is determined by transmission through an etalon filter. The optical transmitter feeds the output of the etalon filter back to an injection current supplied to the LD to reduce phase noise inherently contained in the output light.

Optical transmitter emitting light with narrowed linewidth

A laser apparatus for tuning the emission wavelength of a wavelength tunable laser diode will be described. The apparatus includes a tunable LD with heaters to tune the emission wavelength of the tunable LD, and a controller to control the power supplied to the heaters. A feature of the laser apparatus is that the controller supplies pre-emphasis power to the heaters before the supplement of the power corresponding to the re-tuned emission wavelength to accelerate the stability of the temperature of the heaters.

Laser apparatus and method to re-tune emission wavelength tunable LD

A system includes: a splitter to branch an optical signal output by a wavelength-tunable light source into first to third optical signals; a first photodiode to perform an optical electrical conversion of the first optical signal transmitting a first etalon; a second photodiode to perform an optical electrical conversion of the second optical signal transmitting a second etalon, an FSR of the second etalon being identical to that of the first etalon, peak wavelengths of intensity of a transmitted light of the second etalon being different from those of the first etalon; a third photodiode to perform an optical electrical conversion of the third optical signal; and a controller to control the wavelength-tunable light source with use of a coefficient calculated by following formulas (1) or (2), Coefficient=(PD1&#x2212;A&#xb7;PD3)/(PD2&#x2212;B&#xb7;PD3) (1) and Coefficient=(PD2&#x2212;B&#xb7;PD3)/(PD1&#x2212;A&#xb7;PD3) (2).

System to control wavelength and method to control wavelength

Provided are an optical element and a wavelength monitor capable of detecting a wavelength with high accuracy and at high speed while suppressing a size. The optical element includes: a branch waveguide section configured to branch an input light beam and generate two outputs routed via paths having mutually different optical path lengths; and an optical synthesis section configured to synthesize the two outputs and output two optical signals having different light intensities with regards to a wavelength of the input light beam and exhibiting a mutual phase difference.

Wavelength monitor

A Mach-Zehnder optical modulator includes a join-and-branch portion; two light wave guides connected with the join-and-branch portion; an output light waveguide connected with the join-and-branch portion; arm electrodes respectively provided on the two light waveguides; and a ground electrode that is provided at an edge of at least one of the arm electrodes along the light waveguide, is spaced from the arm electrode and is grounded.

Optical modulator

A Mach-Zehnder optical modulator includes a join-and-branch portion, two light wave guides connected with the join-and-branch portion, two output light waveguides connected with the join-and-branch portion, arm electrodes respectively provided on the two light waveguides, light intensity detection electrodes respectively provided on the two output light waveguides, and a leakage suppression electrode provided between the arm electrodes and the light intensity detection electrodes.

An optical modulation apparatus including: a Mach-Zehnder optical modulator having two optical waveguides, two output optical waveguides and a join-and-branch portion; a phase adjustment circuit configured to output a phase control signal to phase adjustment electrodes provided respectively on the two optical waveguides; a drive circuit configured to output a modulation signal to modulation electrodes provided respectively on the two optical waveguides as a differential signal, the modulation signal modulating lights propagated in the two optical waveguides; and a signal polarity reversal circuit configured to reverse a polarity of the differential signal to be output from the drive circuit.

Optical modulation apparatus, method for controlling optical modulator, and control device for optical modulator

An optical modulation apparatus, including: a Mach-Zehnder optical modulator having two light waveguides, two output light waveguides, and a join-and-branch portion located therebetween; a drive circuit configured to output a modulation signal to modulation electrodes provided respectively on the two light waveguides as a differential signal, the modulation signal modulating lights propagated in the two light waveguides; a phase adjustment circuit configured to control first phase control signals to be output to phase adjustment electrodes provided respectively on the two light waveguides, and adjust phases of lights propagated in the two light waveguides; a phase shift control circuit configured to switch second phase control signals to be output to phase shift electrodes provided respectively on the two light waveguides, and change phases of the lights propagated in the two light waveguides; and a signal polarity reversal circuit configured to reverse a polarity of the differential signal.

Optical modulation apparatus, method for controlling optical modulation apparatus

A method to manufacture an optical device with enhanced high frequency performance is disclosed. The method includes steps of: (a) forming semiconductor layers on a semiconductor substrate, (b) etching the semiconductor layers by using a mask to form a plurality of diffraction gratings, where the mask provides a plurality of periodic patterns each corresponding to respective gratings and having a specific pitch different from others, (c) forming an active layer on the etched semiconductor layers, (d) measuring a maximum optical gain of the active layer, (e) selecting one of diffraction gratings based on the measured optical gain, and (f) forming a current confinement structure aligned with the selected diffraction grating.

Method to manufacture semiconductor device with optical grating

An optical receiver implemented with a pre-amplifier with an additional trans-impedance able to respond to the input signal in bit-by-bit is disclosed. The optical receiver provides a photodiode to convert an optical signal into a photocurrent, a trans-impedance amplifier to convert the photocurrent to a voltage signal, and an additional trans-impedance circuit able to respond instantaneously to the voltage signal. The additional trans-impedance includes a FET whose gate is fully fixedly biased and the source thereof receives the voltage signal. The FET may bypass the current flowing in the intrinsic trans-impedance instantaneously.

Optical receiver with trans-impedance responding in bit-by-bit to input signal

A driver circuit for a semiconductor laser diode (LD) is disclosed, in which the driver circuit drives the LD in the differential mode and lowers the power consumption thereof. The driver circuit includes a differential unit to provide the modulation current to the LD, a voltage converter to provide a positive power supply to the differential unit, a detector to detect the common mode voltage of the differential outputs of the unit, and a comparing unit to control the voltage converter dynamically such that the output common mode voltage is set in a preset reference level.

Driver circuit for semiconductor laser diode driven in differential mode

The invention provides an optical transmitter that prevents the high frequency components in the driving signal from leaking to the external power supply in a wider frequency range. The transmitter provides a shun driving configuration with a switching transistor connected in parallel to the laser diode and a load transistor connected in serial to the parallel circuit of the switching transistor and the laser diode. The load transistor operates in the common base configuration, or the common gate configuration, by which the input impedance viewed from the laser diode becomes large, while, the output impedance viewed from the external power source becomes small. Thus, the high frequency components in the driving signal applied to the switching transistor can be suppresses to appear in the external power source.

Growing community of inventors

Yokohama, Japan

Katsumi Uesaka