Abstract: Provided are a quantum dot laser diode and a method of manufacturing the same. The method of manufacturing a quantum dot laser diode includes the steps of: forming a grating structure layer including a plurality of gratings on a substrate; forming a first lattice-matched layer on the grating structure layer; forming at least one quantum dot layer having at least one quantum dot on the first lattice-matched layer; forming a second lattice-matched layer on the quantum dot layer; forming a cladding layer on the second lattice-matched layer; and forming an ohmic contact layer on the cladding layer. Consequently, it is possible to obtain high gain at a desired wavelength without affecting the uniformity of quantum dots, so that the characteristics of a laser diode can be improved.

Abstract: A semiconductor optical device includes a first mode converting core, a light amplification core, a second mode converting core, and a light modulation core disposed in a first mode converting region, a light amplification region, a second mode converting region, and a light modulating region of a semiconductor substrate, respectively, and a current blocking section covering at least sidewalls and a top surface of the light amplification core. The first mode converting core, the light amplification core, the second mode converting core, and the light modulation core are arranged along one direction in the order named, and are connected to each other in butt joints. The current blocking section includes first, second, and third cladding patterns sequentially stacked. The second cladding pattern is doped with dopants of a first conductivity type, and the first and third cladding patterns are doped with dopants of a second conductivity type.

Abstract: Provided is a double clad fiber device. The double clad fiber device includes a double clad fiber, a pump combiner, at least one first laser diode, and at least one second laser diode. The double clad fiber includes a core and a clad. The pump combiner provides pump light to the core and the clad through one end of the double clad fiber, respectively. The at least one first laser diode provides first pump light to the clad through the pump combiner. The at least one second laser diode provides second pump light to the core through the pump combiner.

Abstract: An optical amplifier includes a passive waveguide region and an active waveguide region. The passive waveguide region is configured to receive an incident optical signal and adjust a mode of the optical signal. The active waveguide region is integrated to the passive waveguide region and configured to perform gain modulation on the optical signal received from the passive waveguide region by changing density of carriers in response to a current applied to the active waveguide region. Internal loss of the active waveguide region is adjusted to produce a resonance effect and thereby to increase bandwidth of the active waveguide. Therefore, the optical amplifier can have a wide bandwidth under a low-current condition.

Abstract: Provided is a tunable laser module emitting an optical signal having high speed, high power and wideband wavelength tuning. The tunable laser module includes a laser array configured to emit an optical signal having a plurality of different lasing wavelengths, a temperature controller configured to change a temperature of the laser array, and an optical integration device configured to modulate or amplify the optical signal at a side of the laser array opposing the temperature controller.

Abstract: A semiconductor optical device includes a first mode converting core, a light amplification core, a second mode converting core, and a light modulation core disposed in a first mode converting region, a light amplification region, a second mode converting region, and a light modulating region of a semiconductor substrate, respectively, and a current blocking section covering at least sidewalls and a top surface of the light amplification core. The first mode converting core, the light amplification core, the second mode converting core, and the light modulation core are arranged along one direction in the order named, and are connected to each other in butt joints. The current blocking section includes first, second, and third cladding patterns sequentially stacked. The second cladding pattern is doped with dopants of a first conductivity type, and the first and third cladding patterns are doped with dopants of a second conductivity type.

Abstract: Provided are a semiconductor optical amplifier and an optical signal processing method using the same. The reflective semiconductor optical amplifier includes: an optical signal amplification region operating to allow a downward optical signal incident from the external to obtain a gain; and an optical signal modulation region connected to the optical signal amplification region and generating a modulated optical signal. The downward optical signal is amplified through a cross gain modulation using the modulated optical signal and is outputted as an upward optical signal.

Abstract: Provided is an external cavity laser light source. The light source includes a substrate, an optical waveguide, and a current blocking layer. The optical waveguide includes a passive waveguide layer, a lower clad layer, an active layer, and an upper clad layer that are sequentially stacked on the substrate and is divided into regions including a linear active waveguide region, a bent active waveguide region, a tapered waveguide region, and a window region. The current blocking layer was formed an outside of the active layer to reduce leakage current. The linear and bent active waveguide regions have a buried heterostructure (BH), and the tapered waveguide region and the window region have a buried ridge stripe (BRS) structure. The passive waveguide layer a width substantially equal to a maximal width of the tapered waveguide region at least in the bent active waveguide region, the tapered waveguide region, and the window region.

Abstract: Provided is a method of forming a compound semiconductor device. In the method, a dopant element layer is formed on an undoped compound semiconductor layer. An annealing process is performed to diffuse dopants in the dopant element layer into the undoped compound semiconductor layer, thereby forming a dopant diffusion region. A rapid cooling process is performed using liquid nitrogen with respect to the substrate having the dopant diffusion region.

Abstract: A quantum dot laser diode and a method of fabricating the same are provided. The quantum dot laser diode includes: a first clad layer formed on an InP substrate; a first lattice-matched layer formed on the first clad layer; an active layer formed on the first lattice-matched layer, and including at least one quantum dot layer formed of an InAlAs quantum dot or an InGaPAs quantum dot which is grown by an alternate growth method; a second lattice-matched layer formed on the active layer; a second clad layer formed on the second lattice-matched layer; and an ohmic contact layer formed on the second clad layer.

Abstract: Provided is a tunable laser module emitting an optical signal having high speed, high power and wideband wavelength tuning. The tunable laser module includes a laser array configured to emit an optical signal having a plurality of different lasing wavelengths, a temperature controller configured to change a temperature of the laser array, and an optical integration device configured to modulate or amplify the optical signal at a side of the laser array opposing the temperature controller.

Abstract: Provided are an optical coupler, which can improve miniaturization and integration, and an active optical module comprising the same. The optical coupler comprises a hollow optical block having a through hole formed to pass an optical fiber therethrough. The hollow optical block comprises at least one incidence plane, at least one internal reflection plane, and at least one tapering region. The incidence plane is disposed at the bottom of the hollow optical block, which is parallel to the through hole, to incident-transmit light. The internal reflection plane is disposed at the top of the hollow optical block, which is opposite to the incidence plane, to reflect the light, which is received from the incidence plane, into the hollow optical block. The tapering region is configured to concentrate the light on the optical fiber in the through hole. The tapering region is formed such that the outer diameter of the hollow optical block decreases away from the internal reflection plane and the incidence plane.

Abstract: Provided is a double clad fiber device. The double clad fiber device includes a double clad fiber, a pump combiner, at least one first laser diode, and at least one second laser diode. The double clad fiber includes a core and a clad. The pump combiner provides pump light to the core and the clad through one end of the double clad fiber, respectively. The at least one first laser diode provides first pump light to the clad through the pump combiner. The at least one second laser diode provides second pump light to the core through the pump combiner.

Abstract: Provided is an optical device module that can improve miniaturization and integration. The optical device module includes a semiconductor optical amplifier having a buried structure and including a first active layer buried in a clad layer disposed on a first substrate, an optical modulator in which a sidewall of a second active layer disposed in a direction of the first active layer on a second substrate junctioned to the first substrate is exposed, the optical modulator having a ridge structure, and at least one multi-mode interference coupler in which the second active layer junctioned to the first active layer is buried in the clad layer, the multi-mode interference coupler sharing the second active layer on the second substrate between the optical modulator and the semiconductor optical amplifier and integrated with the second optical device.

Abstract: Provided is a self-oscillation communication module in which an optical device, a solar battery, and a radio frequency (RF) device are monolithic-integrated. When an active layer of the optical device contains In(Ga)As quantum dots, the optical device can emit light ranging from 800 to 1600 nm and transmit signals at a high speed of 20 Gbps or higher. Since a light absorption layer of the solar battery is formed of InGa(Al)P which has a higher bandgap than silicon and high visible light absorptivity, the solar battery can generate a large current even with a very small light reception area. Therefore, the self-oscillation communication module can always operate using the solar battery without an external power source even in polar regions and deserts and can perform optical communication or high-frequency wireless communication with a wide frequency range.

Abstract: Provided is a wavelength division multiplexed-passive optical network (WDM-PON) apparatus. The WDM-PON includes an optical source unit, an optical mux, and a chirped Bragg grating. The optical source unit generates an optical signal. The optical mux receives the optical signal from the optical source unit through one end of the optical mux, multiplexes the optical signal, and outputs the multiplexed optical signal. The chirped Bragg grating is connected to the other end of the optical mux. The chirped Bragg grating again reflects the optical signal having passed the optical mux to re-input a certain portion of the optical signal into the optical mux and the optical source unit. The optical mux performs a spectrum slicing on the re-inputted optical signal and operates the optical source unit using a channel wavelength of the optical mux as a main oscillation wavelength.

Abstract: A quantum dot laser diode and a method of fabricating the same are provided. The quantum dot laser diode includes: a first clad layer formed on an InP substrate; a first lattice-matched layer formed on the first clad layer; an active layer formed on the first lattice-matched layer, and including at least one quantum dot layer formed of an InAlAs quantum dot or an InGaPAs quantum dot which is grown by an alternate growth method; a second lattice-matched layer formed on the active layer; a second clad layer formed on the second lattice-matched layer, and an ohmic contact layer formed on the second clad layer.

Abstract: Provided are a high-efficiency solar cell, which converts light energy of incident light into electrical energy, and a method of manufacturing the same. An upper ohmic layer is formed at a predetermined tilt angle less than 45° and an ohmic electrode is deposited on the upper ohmic layer so as to reduce shadow loss due to the ohmic electrode and lessen contact resistance.

Abstract: Provided is an external cavity laser light source. The light source includes a substrate, an optical waveguide, and a current blocking layer. The optical waveguide includes a passive waveguide layer, a lower clad layer, an active layer, and an upper clad layer that are sequentially stacked on the substrate and is divided into regions including a linear active waveguide region, a bent active waveguide region, a tapered waveguide region, and a window region. The current blocking layer was formed an outside of the active layer to reduce leakage current. The linear and bent active waveguide regions have a buried heterostructure (BH), and the tapered waveguide region and the window region have a buried ridge stripe (BRS) structure. The passive waveguide layer a width substantially equal to a maximal width of the tapered waveguide region at least in the bent active waveguide region, the tapered waveguide region, and the window region.

Abstract: Provided are a semiconductor laser diode and a method of manufacturing the same. The semiconductor laser diode includes a lower cladding layer disposed on a substrate; a ridge including an optical waveguide layer, an active layer, an upper cladding layer, and an ohmic contact layer, which are sequentially stacked on the lower cladding layer, and having a predetermined width, which is obtained by performing a channel etching process on both sides of the ridge; an oxide layer disposed on surfaces of the upper and lower cladding layer to control the width of the ridge; a dielectric layer disposed on left and right channels of the ridge; an upper electrode layer disposed on the entire surface of the resultant structure to enclose the ridge and the dielectric layer; and a lower electrode layer disposed on a bottom surface of the substrate. The method is simpler than a conventional process of manufacturing a semiconductor laser diode.