Electronics and Telecommunications Research Institute

Jong-Hoi Kim

Joong-Seon Choe

Eun Soo Nam

Chun Ju Youn

Yong-Hwan Kwon

Duk Jun Kim

Kwang-Seong Choi

Yongsoon Baek

Young-Tak Han

Won Seok Han

Kwang-Ryong Oh

Hyun-Soo Kim

Byung-Seok Choi

Dong-Young Kim

Kang-Ho Kim

Jonghyurk Park

Jung-Ho Song

Kyung-Hyun Park

Sung-Bock Kim

Seok-Tae Kim

Sang-Ho Park

Young-Ho Ko

Seo Young Lee

Jang-Uk Shin

Seo-Young Lee

Oh-Kee Kwon

Yong-Soon Baek

Eun-Deok Sim

Dong Hyo Lee

Kyoungwoo Heo

Moon-Ho Park

Provided is a waveguide photodetector including a semiconductor substrate, a first optical waveguide and a second optical waveguide, which are sequentially laminated on the semiconductor substrate, in which each of the first optical waveguide and the second optical waveguide includes a first portion and a second portion, and the first portion extends from the second portion in a first direction parallel to a top surface of the semiconductor substrate, a refractive index matching layer disposed on the second portion of the second optical waveguide, a clad layer disposed on the refractive index matching layer, and an absorber disposed between the refractive index matching layer and the clad layer. Here, the second optical waveguide has a first conductive-type, the clad layer has a second conductive-type opposite to the first conductive-type, and the refractive index matching layer includes a first semiconductor layer that is an intrinsic semiconductor layer.

Waveguide photodetector

Disclosed is an optical receiver. The optical receiver includes an optical splitter that splits an external light signal to output a first light signal and a second light signal, a first amplifier that amplifies the first light signal in a linear gain section to output an amplified first light signal, a second amplifier that amplifies the second light signal in a saturation gain section to output an amplified second light signal, a polarization division hybrid that outputs an in-phase hybrid light signal and a quadrature-phase hybrid light signal, based on a reference light signal and the amplified second light signal, and an optoelectronic conversion unit that outputs an electrical signal, based on the amplified first light signal, the in-phase hybrid light signal, and the quadrature-phase hybrid light signal.

Optical receiver with separated magnitude modulation and phase modulation and operation method thereof

Provided are a coherent optical receiver and a fabrication method thereof, the coherent optical receiver including a substrate, signal and local input waveguides extending in a first direction parallel to a top surface of the substrate and configured to receive an optical signal, a first optical circuit element including a first optical waveguide connected to the signal input waveguide and a trench provided in one side of the first optical waveguide in parallel to the first direction, a second optical circuit element including a second optical waveguide connected to the first optical waveguide, a slit crossing the second optical waveguide, and a wavelength plate inserted to the slit, and third optical circuit elements connected to the second optical circuit element, wherein the first to third optical circuit elements are monolithically integrated in the substrate.

Coherent optical receiver and fabrication method thereof

Provided is an optical module including an optical waveguide device through which multiple channel lightwaves are input and output, an optical transmission/reception unit disposed on one side of the optical waveguide device, an electronic IC disposed on one side of the optical transmission/reception unit and configured to drive the optical transmission/reception unit, a flexible printed circuit board (PCB) disposed on the optical transmission/reception unit and the electronic IC, a first solder ball between the optical transmission/reception unit and the flexible PCB and a second solder ball between the electronic IC and the flexible PCB.

Optical module and solder ball bonding structure

An optical waveguide structure includes a substrate and a core structure disposed on the substrate. The substrate includes a first waveguide region, a second waveguide region, and a transition region between the first waveguide region and the second waveguide region. The core structure includes first core segments arranged in a first direction and a second direction crossing the first direction on the transition region. The core structure includes second core segments arranged in the first direction and the second direction on the second waveguide region. The first direction and the second direction are parallel to a top surface of the substrate.

Optical waveguide structure

Disclosed are a method and an apparatus for transmitting and receiving coherent optical OFDM. The apparatus includes: a transmitted OFDM digital signal processing unit outputting an in-phase (I) component digital signal and a quadrature phase (Q) component digital signal; a digital-analog converter converting the in-phase (I)-component digital signal and the quadrature-phase (Q)-component digital signal into an in-phase (I)-component analog signal and a quadrature-phase (Q)-component analog signal, respectively; an adder adding an additional pilot tone signal to each of the in-phase (I)-component analog signal and the quadrature-phase (Q)-component analog signal outputted from the digital-analog converter; and an optical I/Q modulator up-converting the in-phase (I)-component analog signal added with the additional pilot tone signal and the quadrature-phase (Q)-component analog signal added with the additional pilot tone signal to an optical domain to output a coherent optical OFDM signal including the additional pilot tone signal.

Method and apparatus for transmitting and receiving coherent optical OFDM

Provided is an apparatus and method for measuring IQ imbalance, and in particular, is an apparatus and method for measuring IQ imbalance for an optical receiver. The apparatus for measuring IQ imbalance for an optical receiver includes a light generating unit generating optical and reference signals to provide the optical and reference signals to an optical receiver, a graph creating unit creating a Lissajous figure by using an in-phase (I) signal and a quadrature-phase (Q) signal output from the optical receiver in response to the optical and reference signals, and a calculating unit calculating IQ imbalance for the optical receiver with reference to the Lissajous figure.

Apparatus and method for measuring IQ imbalance for optical receiver

Provide an optical receiver module. The optical receiver module includes: an optical fiber array including a first optical fiber that delivers an optical signal and a second optical fiber that delivers a reference optical signal; a plate optical integrated circuit including first and second multi mode interference (MMI) optical isolators respectively receiving the optical signal and the reference optical signal through a plurality of first optical waveguides; and an optical detector array receiving two optical signals from each of the first and second MMI optical isolators through a plurality of second optical waveguides, wherein the optical detector array includes a plurality of third optical waveguides aligned to be connected to the other end of each of the plurality of second optical waveguides in one-to-one correspondence.

Multi-channel photoreceiver module

Provided is a method of measuring signal transmission time difference of a measuring device. The measuring device according to embodiments, by measuring a skew on two optical paths through signal delays of sufficient sizes for skew measurement on the optical paths, even a skew having a minute size can be measured within a measurable range.

Measuring device and method of measuring signal transmission time difference thereof

An apparatus for measuring performance of a coherent optical receiver includes a beam splitter splitting light into first and second paths, a first optical modulator modulating the first path light, a variable optical attenuator controlling an optical power of the first optical modulator, a first polarization controller transmitting a signal controlling polarization of an output of the variable optical attenuator to the coherent optical receiver, a second optical modulator modulating the second path light, a variable optical delay line delaying time of an output of the second optical modulator, a second polarization controller transmitting a signal controlling polarization of an output of the variable optical delay line to the coherent optical receiver, a network analyzer measuring performance of the coherent optical receiver and controlling the optical modulators, and a controller transmitting a control signal to the optical modulators.

Apparatus for measuring performance of coherent optical receiver

Provided is a polarization division multiplexed optical OFDM transmitter. The polarization division multiplexed optical OFDM transmitter includes a data demultiplexer, a training symbol generation unit and an optical up-converter and polarization division multiplexing unit. The data demultiplexer divides a transmission signal into a plurality of groups. The training symbol generation unit allocates a plurality of training symbols for each OFDM data which is included in the respective multiplexed groups, and allocates repetitive data in a time domain for the respective training symbols for data of 0 to periodically appear for the respective training symbols in a frequency domain. The optical up-converter and polarization division multiplexing unit performs optical frequency band conversion and polarization division multiplexing on an output of the training symbol generation unit to output a polarization division multiplexed optical OFDM signal corresponding to a plurality of polarization components.

Polarization division multiplexed optical orthogonal frequency division multiplexing transmitter and receiver

Provided is an optical OFDM receiver. The optical OFDM receiver receives an optical signal dependent on the nonlinearity of a transmitter. The optical OFDM receives includes an optical down converter, a nonlinearity compensator, and an OFDM demodulator. The optical down converter converts the optical signal into an electrical signal. The nonlinearity compensator filters the electrical signal, for compensating distortion which is added to the optical signal when the transmitter performs optical modulation. The OFDM demodulator demodulates the distortion-compensated electrical signal in an OFDM scheme.

Optical orthogonal frequency division multiplexing receiver and optical signal receiving method thereof

Provided are an adapter assembly and method for compensating optical fibers for a length difference. The adapter assembly includes a first adapter, a second adapter, and a member. The first adapter is configured to be connected to at least one optical communication unit. The second adapter is configured to be connected to at least another optical communication unit and be coupled to the first adapter. The member is configured to be interposed between the first and second adapters for providing an optical signal transmission path between the optical communication units. Owing to the member, a length difference between optical fibers can be compensated for.

Adapter assembly and method for compensating optical fibers for length difference

Disclosed is a high speed optical signal processor which includes a saturable absorber area including a substrate, an active layer, a clad layer and a first upper electrode which are sequentially formed on one face of the substrate, and a first lower electrode formed on the other face of the substrate; and a gain-clamped optical amplifier area including a substrate having a diffraction grating for generating a laser beam, an active layer, a clad layer and a second upper electrode which are sequentially formed on one face of the substrate, and a second lower electrode formed on the other face of the substrate, the second upper electrode being isolated from the first upper electrode of the saturable absorber area.

High speed optical signal processor including saturable absorber and gain-clamped optical amplifier

Disclosed is a method for the fabrication of a spot-size converter with a lateral-tapered waveguide (or an active layer), which utilizes a mask during a lithographic process wherein the mask has a pad that can absorb strain to be occurred during forming a lateral-tapered waveguide pattern at its distal end and the lateral-tapered waveguide is fabricated by forming the distal end on the order of about 0.6 &mgr;m in width followed by forming the lateral-tapered waveguide on the order of 0.1 &mgr;m using an wet etching. Thus, it is possible to reduce a fabrication cost because it is free from a high-resolution electron beam lithography and a stepper, and hence enhance a reproducibility of the lateral-tapered waveguide because it is free from an excessive wet etching during the use of a contact exposure equipment. Further, it is possible to integrate the spot-size converter fabricated by the above with an optical device, resulting in an increased position adjustment and reproducibility of the spot-size converter, which in turn, leads to increase in yield for the optical device.

Growing community of inventors

Daejeon, South Korea

Jong-Hoi Kim