Abstract: A method and apparatus for notifying status of an MN in a WLAN system using VLC are provided, in which an AP allocates a first predetermined number of time slots per frame as unallocated slots, for status notification of an initially accessing MN and allocates a second predetermined number of time slots per frame as reserved slots, for status notification of an initially accessing MN and uplink data transmission of an MN, and the MN transmits a visible light signal carrying status information about the MN in one of an unallocated slot and a reserved slot, if the MN initially accesses the AP.

Abstract: A system and method for continuing a communication link while maintaining visibility in visible light communication. A frame is transmitted by a sender for establishing a communication link before data transmission to a receiver by a sender. A receiver sends a response frame that reports on establishment of the communication link prior to data transmission by the sender. A data frame containing information is transmitted by the sender to the receiver. An acknowledgment frame is transmitted to the sender in response to the data frame. A disconnect frame is transmitted by the sender which is acknowledged by the receiver. A visible sequence is transmitted during a time period when the sender and the receiver do not transmit respective frames for communication to maintain visibility between two devices that may be communicating otherwise by, for example, infrared communication.

Abstract: Disclosed is a passive optical network comprising a central office including a plurality of first reflective semiconductor optical amplifiers of a quantum-dot type, each of which generates a wavelength-seeded downstream optical signal on a downstream channel of a corresponding wavelength, a plurality of optical network units each of which includes a second reflective semiconductor optical amplifier of a multi-quantum-well type, the second reflective semiconductor optical amplifier generating a wavelength-seeded upstream optical signal on an upstream channel of a corresponding wavelength and a remote node for outputting the downstream optical signals to corresponding optical network units, and multiplexing and outputting the upstream optical signals to the central office.

Abstract: A wavelength division multiplexed self-healing passive optical network using a wavelength injection method includes a central office for coupling modulated multiplexed optical signals (MMOS) and broadband optical signals (BOS)for an upstream light source into one signal transmitted to a plurality of optical network units (ONUs) through a working main fiber and a protection main fiber. A remote node connects to the central office via the main fiber and protection main fiber and to the ONUs through working distribution fibers and protection distribution fibers. The remote node demultiplexes the MMOS and the (BOS) for an upstream light source. The remote node transmits demultiplexed signals to the ONUs, which receive the modulated optical signals and the BOS for an upstream light source which corresponds to predetermined ONUs, and demodulate the modulated optical signals, and modulate upstream optical signals via demultiplexed BOS for an upstream light source.

Abstract: An optical transmitter including a multi-lambda source to output injection light consisting of a plurality of injection wavelengths in channels, a circulator having a first port, a second port, and a third port, the circulator receiving the injection light at the first port, and outputting the received injection light to the second port, and further receiving signal light at the second port, and outputting the received signal light to the third port, an arrayed waveguide grating having a multiplexing port connected to the second port of the circulator, and a plurality of demultiplexing ports, spectrum-slicing injection light received from the circulator at the multiplexing port into a plurality of injection channels, and outputting the injection channels to the demultiplexing ports and further receiving and multiplexing a plurality of signal channels at the demultiplexing ports, into a signal light, and outputting the signal light to the multiplexing port, and a plurality of reflective semiconductor optical a

Abstract: A method for communication link connection in a data transmission between devices using visible light communication (VLC) that can provide a visible indication prior to establishing a communication link between the devices. The method includes activating a VLC mode by a first VLC apparatus in order to transmit the data; scanning other apparatuses to establish a communication link with a second VLC apparatus; requesting a communication link to the second VLC apparatus in order to transmit the data; and receiving a response, indicating whether data can be received from the second VLC apparatus, and establishing communication link connection. A user can easily recognize the visual indication before the establishment of the communication link, providing an opportunity for the user to arrange the apparatus for optimal communication distance/angle from another device, and for a status of the communication.

Abstract: A wireless communication interface for a portable wireless terminal and a system for wirelessly communicating by a portable wireless terminal with another device via a free space. The interface facilitates aligning the portable wireless device with another devices for improved communication. The interface including: a light source for generating a data-modulated visible light signal and outputting the visible light signal to the free space; an optical detector for generating an electrical signal by photoelectrically converting the visible light signal input from the free space, and for outputting the electrical signal. A demodulation unit demodulates the electrical signal input from the optical detector, and outputs a data signal.

Abstract: An apparatus and method for controlling the emitted color of visible light according to the current communication state in a visible light communication (VLC) device. The method includes storing one or more communication states and emitting colors that are correspondingly matched to the one or more communication states to indicate each of the various communication states. The VLC also checks, which can be based upon selection of a VLC mode, the current communication state and an emits a color that corresponds to the current communication state and emits the checked color of light to provide a visible light signal that indicates communication status to a user.

Abstract: A wavelength-division-multiplexed light source for transmitting broadband light through a fiber and receiving an optical signal through the fiber is disclosed. The wavelength-division-multiplexed light source includes: a light source for outputting broadband light; and a coupler for outputting the broadband light, which has been input from the light source, to the fiber through cross coupling, and outputting an optical signal, which has been input from the fiber, through bar coupling, based on a predetermined cross coupling ratio, wherein the cross coupling ratio of the coupler is adjusted depending on a power of the optical signal.

Abstract: A transmitting apparatus using a multiple lambda source in WDM network, which has an improved structure to minimize costs and efforts and reduce time delay that may be incurred through wavelength shift. The transmitting apparatus comprises: a multiple lambda source providing a signal with multiple wavelengths, which carries no information; a first optical circulator for transferring the signal with multiple wavelengths carrying no information, which has been transmitted from the multiple lambda sources, to multiplexer/demultiplexer, the first optical circulator transferring a multiplexed signal from the multiplexer/demultiplexer. The multiplexer/demultiplexer demultiplexes the multiple wavelength optical signal from the first optical circulator and for multiplexing optical signals of each wavelength on which information is loaded.

Abstract: A bidirectional add/drop multiplexer includes first input/output unit inputs a first optical signal multiplexed from a plurality of odd channels and outputs a second optical signal multiplexed from a plurality of added or dropped even channels; a second input/output unit outputs the first optical signal multiplexed from a plurality of added or dropped odd channels and outputs the second optical signal multiplexed from a plurality of even channels; an optical arrayed waveguide grating for multiplexing added or dropped odd channels of the first optical signal input to a first terminal for subsequent transmission to the second input/output unit, multiplexing added or dropped even channels of the second optical signal input to a second terminal for subsequent transmission to the first input/output unit; and an optical combining unit that amplifies the first optical signal and the second optical signal input from the first input/output unit and the second input/output unit.

Abstract: An optical fiber amplifier features an optical amplifying section for amplifying an inputted optical signal. A sampling section is provided for shunting part of the optical signal amplified by the optical amplifying section and detecting a first test light belonging to a short wavelength band and a second test light belonging to a long wavelength band. An input power control circuit serves to compare respective powers of the first and second test lights and then outputs a control signal for controlling an input power of the optical signal inputted to the optical amplifying section according to the power differential of the first and second test lights. An output power control circuit derives an output power of the optical amplifying section from the power of the optical signal shunted at the sampling section and also controls the optical amplifying section so that the output power of the optical amplifying section attains a predetermined value.

Abstract: Disclosed is a passive optical network comprising a central office including a plurality of first reflective semiconductor optical amplifiers of a quantum-dot type, each of which generates a wavelength-seeded downstream optical signal on a downstream channel of a corresponding wavelength, a plurality of optical network units each of which includes a second reflective semiconductor optical amplifier of a multi-quantum-well type, the second reflective semiconductor optical amplifier generating a wavelength-seeded upstream optical signal on an upstream channel of a corresponding wavelength and a remote node for outputting the downstream optical signals to corresponding optical network units, and multiplexing and outputting the upstream optical signals to the central office.

Abstract: An optical transmitter including a multi-lambda source to output injection light consisting of a plurality of injection wavelengths in channels, a circulator having a first port, a second port, and a third port, the circulator receiving the injection light at the first port, and outputting the received injection light to the second port, and further receiving signal light at the second port, and outputting the received signal light to the third port, an arrayed waveguide grating having a multiplexing port connected to the second port of the circulator, and a plurality of demultiplexing ports, spectrum-slicing injection light received from the circulator at the multiplexing port into a plurality of injection channels, and outputting the injection channels to the demultiplexing ports and further receiving and multiplexing a plurality of signal channels at the demultiplexing ports, into a signal light, and outputting the signal light to the multiplexing port, and a plurality of reflective semiconductor optical a

Abstract: An optical fiber amplifier is disclosed for amplifying an input optical signal in the long wavelength band. The amplifier include first and second pumping light sources, a photo detector for detecting the intensity of the input optical signal, an erbium-doped optical fiber, and a controller. The optical fiber is brought to a first-pumped state by the first pumping light output from the first pumping light source. This generates an amplified spontaneous emission in the short wavelength band. The optical fiber is brought to a second-pumped state by the amplified spontaneous emission and outputs an induced emission light in the long wavelength band. The second pumping light source outputs a second pumping light in the same wavelength band as the amplified spontaneous emission, while controlling the intensity of the second pumping light by an output control signal, thereby controlling the intensity of the second-pumped state of the optical fiber.

Abstract: A wavelength division multiplexed self-healing passive optical network using a wavelength injection method. The wavelength division multiplexed self-healing passive optical network includes a central office for coupling modulated multiplexing optical signals and broadband optical signals for an upstream light source. These signals are combined into one signal and transmitted to a plurality of optical network units as a coupled signal through a working main fiber and a protection main fiber. The remote node connects to the central office through the working main fiber and the protection main fiber and to the optical network units through working distribution fibers and protection distribution fibers. The remote node demultiplexes the modulated multiplexing optical signals and the broadband optical signals for an upstream light source.

Abstract: Disclosed is a multi-lambda source for outputting an optical signal having a plurality of channels, the multi-lambda source comprising an optical fiber amplifier, having a back and front end, for amplifying an optical signal received from the back end and outputting ASE light to the back end, a reflector coupled to the back end of the optical fiber amplifier for reflecting a received optical signal, and a comb filter arranged between the optical fiber amplifier and the reflector and having a pass band of wavelengths for filtering the ASE light and generating the optical signal of the channels according to a transmission spectrum of the filtered ASE light.

Abstract: A transmitting apparatus using a multiple lambda source in WDM network, which has an improved structure to minimize costs and efforts and reduce time delay that may be incurred through wavelength shift. The transmitting apparatus comprises: a multiple lambda source providing a signal with multiple wavelengths, which carries no information; a first optical circulator for transferring the signal with multiple wavelengths carrying no information, which has been transmitted from the multiple lambda sources, to multiplexer/demultiplexer, the first optical circulator transferring a multiplexed signal from the multiplexer/demultiplexer. The multiplexer/demultiplexer demultiplexes the multiple wavelength optical signal from the first optical circulator and for multiplexing optical signals of each wavelength on which information is loaded.

Abstract: An optical fiber amplifier features an optical amplifying section for amplifying an inputted optical signal. A sampling section is provided for shunting part of the optical signal amplified by the optical amplifying section and detecting a first test light belonging to a short wavelength band and a second test light belonging to a long wavelength band. An input power control circuit serves to compare respective powers of the first and second test lights and then outputs a control signal for controlling an input power of the optical signal inputted to the optical amplifying section according to the power differential of the first and second test lights. An output power control circuit derives an output power of the optical amplifying section from the power of the optical signal shunted at the sampling section and also controls the optical amplifying section so that the output power of the optical amplifying section attains a predetermined value.

Abstract: Disclosed is a multi-lambda source for outputting an optical signal having a plurality of channels, the multi-lambda source comprising an optical fiber amplifier, having a back and front end, for amplifying an optical signal received from the back end and outputting ASE light to the back end, a reflector coupled to the back end of the optical fiber amplifier for reflecting a received optical signal, and a comb filter arranged between the optical fiber amplifier and the reflector and having a pass band of wavelengths for filtering the ASE light and generating the optical signal of the channels according to a transmission spectrum of the filtered ASE light.