Abstract: A semiconductor optical device includes: a semiconductor layer having a projection; a multiple quantum well layer on the projection; a pair of first semiconductor layers in contact with the mesa stripe structure on respective both sides; a pair of second semiconductor layers on the semiconductor layer; a pair of resin layers above the second semiconductor layers; a pair of third semiconductor layers on the second semiconductor layers, each third semiconductor layer surrounding a corresponding one of the resin layers, the third semiconductor layers being different in constituent material from the second semiconductor layers; a first electrode on the semiconductor layer; and a second electrode including a mesa electrode on the mesa stripe structure, a lead-out electrode extending in the second direction from the mesa electrode, and a pad electrode above one of the resin layers, the pad electrode being connected to the lead-out electrode.

Abstract: A device includes: a mesa stripe structure comprising a semiconductor in a stripe shape extending in a first direction, with first and second portions spaced apart in the first direction, and a third portion between the first and second portions; and an electrode pattern including a first electrode overlapping with the first portion but not overlapping with the second portion, and a second electrode overlapping with the second portion but not overlapping with the first portion. The first and second electrodes are separated. The electrode pattern comprises a metal in a shape of not overlapping with the third portion. The electrode pattern includes an adjacent area not overlapping with the mesa stripe structure. The adjacent area is next to the third portion in a second direction orthogonal to the first direction, and is on a semiconductor layer continuous to the mesa stripe structure.

Abstract: Provided is an electro-absorption modulator that includes a substrate, a mesa structure, a first conductivity type electrode, and a second conductivity type electrode. The first conductivity type electrode includes a mesa-top electrode, a pad electrode, and a lead-out wire electrode. The mesa structure has a light input end, to which light is to be input from outside, and a light output end, which is on a side of the mesa structure that is opposite of the light input end. A connection position between a center position in a short-side direction of the lead-out wire electrode and the mesa-top electrode is closer to the light output end side in a long-side direction of the mesa-top electrode. The connection position is a position that is less than 50% from the light output end side with respect to a length in the long-side direction of the mesa-top electrode.

Abstract: A buried semiconductor optical device comprises a semiconductor substrate; a mesa-stripe portion including a multi-quantum well layer on the semiconductor substrate; a buried layer consisting of a first portion and a second portion, the first portion covering one side of the mesa-stripe portion, the second portion covering the other side of the mesa-stripe portion, and the first portion and the second portion covering a surface of the semiconductor substrate; and an electrode configured to cause an electric current to flow through the mesa-stripe portion, the buried layer comprising, from the surface, a first, second, and third sublayer, the first and third sublayer each consisting of semi-insulating InP, the first sublayer and the second sublayer forming a pair structure, the second sublayer being located above the multi-quantum well layer, and the second sublayer consisting of one or more layers selected from InGaAs, InAlAs, InGaAlAs, InGaAsP, and InAlAsP.

Abstract: An optical semiconductor device includes a semiconductor substrate with a protrusion that forms a lower end portion of a mesa stripe structure in a stripe shape extending in a first direction; a multi-quantum well layer in a stripe shape extending in the first direction on the protrusion, wherein the multi-quantum well layer forms an intermediate portion of the mesa stripe structure; a semiconductor layer in a stripe shape extending in the first direction on the intermediate portion, wherein the semiconductor layer forms an upper end portion of the mesa stripe structure; and a semi-insulating semiconductor layer in contact with side surfaces of the mesa stripe structure on both sides in a second direction perpendicular to the first direction. The optical semiconductor device may include a first electrode on a surface of the semiconductor substrate and/or a second electrode on the upper end surface of the mesa stripe structure.

Abstract: An optical transmitter module includes optical semiconductor devices including a first optical semiconductor device, a temperature adjustment means for collectively performing temperature adjustment on the optical semiconductor devices, and a first thermal resistor that is disposed between the first optical semiconductor device and the temperature adjustment means, in which, when the temperature adjustment means is driven, the temperature of the first optical semiconductor device is higher than temperatures of other optical semiconductor devices which are different from the first optical semiconductor device.

Abstract: A buried semiconductor optical device comprises a semiconductor substrate; a mesa-stripe portion including a multi-quantum well layer on the semiconductor substrate; a buried layer consisting of a first portion and a second portion, the first portion covering one side of the mesa-stripe portion, the second portion covering the other side of the mesa-stripe portion, and the first portion and the second portion covering a surface of the semiconductor substrate; and an electrode configured to cause an electric current to flow through the mesa-stripe portion, the buried layer comprising, from the surface of the semiconductor substrate, a first sublayer, a second sublayer, and a third sublayer, the first sublayer, the second sublayer, and the third sublayer each consisting of semi-insulating InP, the first sublayer and the second sublayer forming a pair structure, the second sublayer being located above the multi-quantum well layer from the surface of the semiconductor substrate, and the second sublayer consisting

Abstract: An optical semiconductor device includes a semiconductor substrate; a plurality of mesa stripes, which are arranged side by side on the semiconductor substrate, and each of which includes an active layer and a diffraction grating, the diffraction grating extending up to a back end surface of each of the plurality of mesa stripes; a plurality of electrodes, each of which is electrically connected to an upper surface of a corresponding one of the plurality of mesa stripes, having a pad portion for wire bonding; a plurality of waveguides, each of which is optically connected to the active layer of a corresponding one of the plurality of mesa stripes; and a reflective film provided at back end surfaces of the plurality of mesa stripes and having a reflectivity of 30% or more, wherein a center-to-center distance at back end surfaces of two mesa stripes at both ends of the plurality of mesa stripes is 150 ?m or less, and wherein at least two mesa stripes, of the plurality of mesa stripes, are configured to be drive

Abstract: Provided is an optical transmission module which can generate PAM4 optical modulation signals without converting a plurality of binary electric signals to a multi-level electric signal. An optical transmission module (200) comprising: a light source (60) for emitting continuous waveform (CW) light; optical modulators (51,52,53) arranged in series with a path of the CW light configured to modulate the CW light by switching relatively large absorption and relatively small absorption of the optical modulators in response to a modulation signal applied to the respective optical modulators; and an arithmetic logic circuit (100) configured to receive a plurality of binary electrical signals, and then to perform logic operation on the plurality of binary electrical signals for generating a new plurality of binary electrical signals, wherein each of the new plurality of binary electrical signals is applied to the respective optical modulators as the modulation signal.

Abstract: Provided is an optical transmission module which can generate PAM4 optical modulation signals without converting a plurality of binary electric signals to a multi-level electric signal. An optical transmission module (200) comprising: a light source (60) for emitting continuous waveform (CW) light; optical modulators (51,52,53) arranged in series with a path of the CW light configured to modulate the CW light by switching relatively large absorption and relatively small absorption of the optical modulators in response to a modulation signal applied to the respective optical modulators; and an arithmetic logic circuit (100) configured to receive a plurality of binary electrical signals, and then to perform logic operation on the plurality of binary electrical signals for generating a new plurality of binary electrical signals, wherein each of the new plurality of binary electrical signals is applied to the respective optical modulators as the modulation signal.

Abstract: An optical transmitter module includes optical semiconductor devices including a first optical semiconductor device, a temperature adjustment means for collectively performing temperature adjustment on the optical semiconductor devices, and a first thermal resistor that is disposed between the first optical semiconductor device and the temperature adjustment means, in which, when the temperature adjustment means is driven, the temperature of the first optical semiconductor device is higher than temperatures of other optical semiconductor devices which are different from the first optical semiconductor device.

Abstract: Provided is an optical transmission module in which noise is further reduced. The optical transmission module includes a first semiconductor layer having a first electrode arranged thereon, an active layer with a stripe shape formed on the first semiconductor layer, and a second semiconductor layer with a stripe shape formed on the active layer. The second semiconductor layer has a second electrode arranged thereon and includes a diffraction grating arranged along an extending direction of the active layer. The active layer includes a first portion having first stripe width, a second portion having a second stripe width smaller than the first stripe width, and a connection portion having a varying stripe width so as to connect the first portion and the second portion to each other. The diffraction grating overlaps with the first portion and does not overlap with the second portion in planar view.

Abstract: Multilevel optical intensity modulation high in accuracy is performed using electro-absorption optical modulators. There is provided a plurality of EA modulators connected in series in a path of an optical signal from a light source, and a multilevel-coded modulated optical signal is generated by modulating an intensity of an input optical signal from the light source based on a modulation signal using the EA modulators. Each of the EA modulators is switched between an ON state and an OFF state of optical absorption in accordance with the modulation signal. Regarding an extinction ratio of the ON state to the OFF state in each of the EA modulators, the EA modulators have respective values difference from each other, and are arranged in ascending order of the extinction ratio from the light source side.

Abstract: Provided is an optical transmission module in which noise is further reduced. The optical transmission module includes a first semiconductor layer having a first electrode arranged thereon, an active layer with a stripe shape formed on the first semiconductor layer, and a second semiconductor layer with a stripe shape formed on the active layer. The second semiconductor layer has a second electrode arranged thereon and includes a diffraction grating arranged along an extending direction of the active layer. The active layer includes a first portion having first stripe width, a second portion having a second stripe width smaller than the first stripe width, and a connection portion having a varying stripe width so as to connect the first portion and the second portion to each other. The diffraction grating overlaps with the first portion and does not overlap with the second portion in planar view.

Abstract: Preferable simultaneous achievement of the target characteristics with respect to both of the modulation bandwidth and the extinction ratio in the optical intensity modulation using the electro-absorption optical modulator is realized with a simple circuit configuration. The modulator integrated semiconductor laser element includes a plurality of EA modulators disposed in series in an optical signal path, and each adapted to absorb light in accordance with an applied voltage. The modulator driver for supplying the EA modulator with the applied voltage is provided for each of the EA modulators. The plurality of modulator drivers generates the applied voltage common to the plurality of EA modulators in accordance with a control signal. The modulator lengths of the plurality of EA modulators are set so that the closer to the light source the EA modulator is, the shorter the modulator length is.

Abstract: Preferable simultaneous achievement of the target characteristics with respect to both of the modulation bandwidth and the extinction ratio in the optical intensity modulation using the electro-absorption optical modulator is realized with a simple circuit configuration. The modulator integrated semiconductor laser element includes a plurality of EA modulators disposed in series in an optical signal path, and each adapted to absorb light in accordance with an applied voltage. The modulator driver for supplying the EA modulator with the applied voltage is provided for each of the EA modulators. The plurality of modulator drivers generates the applied voltage common to the plurality of EA modulators in accordance with a control signal. The modulator lengths of the plurality of EA modulators are set so that the closer to the light source the EA modulator is, the shorter the modulator length is.

Abstract: Multilevel optical intensity modulation high in accuracy is performed using electro-absorption optical modulators. There is provided a plurality of EA modulators connected in series in a path of an optical signal from a light source, and a multilevel-coded modulated optical signal is generated by modulating an intensity of an input optical signal from the light source based on a modulation signal using the EA modulators. Each of the EA modulators is switched between an ON state and an OFF state of optical absorption in accordance with the modulation signal. Regarding an extinction ratio of the ON state to the OFF state in each of the EA modulators, the EA modulators have respective values difference from each other, and are arranged in ascending order of the extinction ratio from the light source side.

Abstract: A communication system includes a termination-side optical transmitter comprising a reflective semiconductor optical amplifier, a reflective unit configured to reflect output light from the termination-side optical transmitter, and a terminal station-side optical receiver connected to the termination-side optical transmitter via a transmission line and configured to receive the output light from the termination-side optical transmitter by limiting a frequency band of the output light. The reflective semiconductor optical amplifier amplifies the output light reflected by the reflective unit, modulates the amplified output light based on an electric signal, and outputs the modulated output light.

Abstract: Provided is a semiconductor optical device, which has a buried heterostructure structure and is formed in a structure capable of reducing a parasitic capacitance to further improve characteristics thereof, and also provided are an optical transmitter module, an optical transceiver module, and an optical transmission equipment. The semiconductor optical device includes a modulator portion for modulating light input along an emitting direction and radiating the modulated light, the modulator portion including: a mesa-stripe structure, which includes an active layer and extends in the emitting direction; and a buried layer provided adjacent to each side of the mesa-stripe structure, in which a distance between a lower surface of the buried layer and a lower surface of the active layer is 20% or more of a distance between the lower surface and an upper surface of the buried layer.

Abstract: Provided is a semiconductor optical device, which has a buried heterostructure structure and is formed in a structure capable of reducing a parasitic capacitance to further improve characteristics thereof, and also provided are an optical transmitter module, an optical transceiver module, and an optical transmission equipment. The semiconductor optical device includes a modulator portion for modulating light input along an emitting direction and radiating the modulated light, the modulator portion including: a mesa-stripe structure, which includes an active layer and extends in the emitting direction; and a buried layer provided adjacent to each side of the mesa-stripe structure, in which a distance between a lower surface of the buried layer and a lower surface of the active layer is 20% or more of a distance between the lower surface and an upper surface of the buried layer.