Abstract: Provided is a lubricity improver capable of improving lubricity and storage stability due to anti-oxidation, the lubricity improver containing a saturated fatty acid methyl ester derivative including at least one 1,2-dimethoxy ethylene structural unit represented by Chemical Formula a below, obtained by converting a double bond (olefin) of biodiesel, which is used as a lubricity improver of fuel, that is, the existing fatty acid methyl ester (FAME), into a dimethoxy group.

Abstract: Provided is a lubricity improver capable of improving lubricity and storage stability due to anti-oxidation, the lubricity improver containing a saturated fatty acid methyl ester derivative including at least one 1,2-dimethoxy ethylene structural unit represented by Chemical Formula a below, obtained by converting a double bond (olefin) of biodiesel, which is used as a lubricity improver of fuel, that is, the existing fatty acid methyl ester (FAME), into a dimethoxy group.

Abstract: A semiconductor monolithic integrated optical transmitter including a plurality of active layers formed on a semiconductor substrate is disclosed, which comprises: a distributed feedback laser diode including a grating for reflecting light with a predetermined wavelength and a first active layer for oscillating received light from the grating; an electro-absorption modulator including a second active layer for receiving light from the first active layer, wherein the received light intensity is modulated through a change of absorbency in accordance with an applied voltage; an optical amplifier including a third active layer for amplifying received light from the second active layer; a first optical attenuator between the first active layer and the second active layer; and a second optical attenuator between the second active layer and the third active layer.

Abstract: Disclosed is a distributed Bragg reflector laser, which includes: an active layer; a first guide layer provided with a plurality of first gratings on an upper surface thereof and formed on one side of the active layer; and, a second guide layer provided with a plurality of second gratings on an upper surface thereof, wherein the second guide layer is formed on the other side of the active layer opposite to the first guide layer.

Abstract: A semiconductor monolithic integrated optical transmitter including a plurality of active layers formed on a semiconductor substrate is disclosed, which comprises: a distributed feedback laser diode including a grating for reflecting light with a predetermined wavelength and a first active layer for oscillating received light from the grating; an electro-absorption modulator including a second active layer for receiving light from the first active layer, wherein the received light intensity is modulated through a change of absorbency in accordance with an applied voltage; an optical amplifier including a third active layer for amplifying received light from the second active layer; a first optical attenuator between the first active layer and the second active layer; and a second optical attenuator between the second active layer and the third active layer.

Abstract: The present invention provides a wavelength-tunable laser apparatus which is capable of obtaining a high output while suppressing the generation of spontaneous emission, as well as having a broad wavelength-tunable range.

Abstract: Disclosed is a distributed Bragg reflector laser, which includes: an active layer; a first guide layer provided with a plurality of first gratings on an upper surface thereof and formed on one side of the active layer; and, a second guide layer provided with a plurality of second gratings on an upper surface thereof, wherein the second guide layer is formed on the other side of the active layer opposite to the first guide layer.

Abstract: The present invention provides a wavelength-tunable laser apparatus which is capable of obtaining a high output while suppressing the generation of spontaneous emission, as well as having a broad wavelength-tunable range.

Abstract: A wavelength converter is provided. The wavelength converter includes a substrate; first and second semiconductor optical amplifiers (SOAs) provided in parallel on the substrate, each of the SOAs including a first portion which passes light at one end, and a second portion which passes light at the opposite end; a first waveguide connected to the second portions of the first and second SOAs; a second waveguide connected to the first portion of the first SOA; and a third waveguide connected to the first portions of the first and second SOAs. The first through third waveguides are arranged on one side of the substrate in the vicinity of the first portions of the first and second SOAs. The first waveguide is connected to the second portions of the first and second SOAs through a unit for changing an optical progressing path.

Abstract: Disclosed is a polarization insensitive semiconductor optical amplifier (SOA) in an optical amplifying element having a substrate and a multi-layer structure, crystal growth layer including an active layer formed on the substrate. In the inventive optical amplifier, the active layer is divided into first and second areas having different polarization modes. An electrode means independently applies currents to the first and second areas. Therefore, the polarization insensitive semiconductor optical amplifier is capable of separately controlling TE and TM polarization gains so as to approximately equalize the TE polarization gain to the TM polarization gain.

Abstract: A wavelength converter is provided. The wavelength converter includes a substrate; first and second semiconductor optical amplifiers (SOAs) provided in parallel on the substrate, each of the SOAs including a first portion which passes light at one end, and a second portion which passes light at the opposite end; a first waveguide connected to the second portions of the first and second SOAs; a second waveguide connected to the first portion of the first SOA; and a third waveguide connected to the first portions of the first and second SOAs. The first through third waveguides are arranged on one side of the substrate in the vicinity of the first portions of the first and second SOAs. The first waveguide is connected to the second portions of the first and second SOAs through a unit for changing an optical progressing path.