Jyung Chan Lee

Mode division multiplexed optical transmission enabled by all–fiber mode multiplexer

Mode division multiplexed optical transmission enabled by all-fiber mode multiplexer is investigated. The proposed all-fiber mode multiplexer is composed of consecutive mode selective couplers. It multiplexes or demultiplexes LP01, LP11, LP21, and LP02 modes simultaneously. We demonstrate successful transmission of three spatial modes with 120 Gb/s PDM-QPSK signals over 15 km of four mode fiber by using 6x6 MIMO digital signal processing.

A 10-Gb/s CMOS CDR and DEMUX IC With a Quarter-Rate Linear Phase Detector

This paper presents a 10-Gb/s clock and data recovery (CDR) and demultiplexer IC in a 0.13-mum CMOS process. The CDR uses a new quarter-rate linear phase detector, a new data recovery circuit, and a four-phase 2.5-GHz LC quadrature voltage-controlled oscillator for both wide phase error pulses and low power consumption. The chip consumes 100 mA from a 1.2-V core supply and 205 mA from a 2.5-V I/O supply including 18 preamplifiers and low voltage differential signal (LVDS) drivers. When 9.95328-Gb/s 231-1 pseudorandom binary sequence is used, the measured bit-error rate is better than 10-15 and the jitter tolerance is 0.5UIpp, which exceeds the SONET OC-192 standard. The jitter of the recovered clock is 2.1 psrms at a 155.52MHz monitoring clock pin. Multiple bit rates are supported from 9.4 Gb/s to 11.3 Gb/s

A 10Gb/s CMOS CDR and DEMUX IC with a Quarter-Rate Linear Phase Detector

A 10Gb/s CDR and DEMUX IC in a 0.13mum CMOS consumes 100mA from a 1.2V core supply and 205mA from a 2.5V I/O supply including 18 LVDS drivers. The CDR system uses a quarter-rate linear phase detector and a 4-phase 2.5GHz LC-QVCO to achieve a BER of <10-15 and a jitter tolerance of 0.5UIpp exceeding the OC-192 standard

Mode- and wavelength-division multiplexed transmission using all-fiber mode multiplexer based on mode selective couplers.

We propose all-fiber mode multiplexer composed of two consecutive LP₁₁ mode selective couplers that allows for the multiplexing of LP₀₁ mode and two-fold degenerate LP₁₁ modes. We demonstrate WDM transmission of 32 wavelength channels with 100 GHz spacing, each carrying 3 modes of 120 Gb/s polarization division multiplexed quadrature phase shifted keying (PDM-QPSK) signal, over 560 km of few-mode fiber (FMF). Long distance transmission is achieved by 6×6 multiple-input multiple-output digital signal processing and modal differential group delay compensated link of FMF. The all-fiber mode multiplexer has considerable potential to be used in mode- and wavelength-division multiplexed transmission.

Design of RoF based mobile fronthaul link with multi-IF carrier for LTE/LTE-A signal transmission

We report a design of RoF based mobile fronthaul link considering quality of optical link and LTE/LTE-A signal simultaneously. The requirement of CNR in analog link supporting LTE/LTE-A services is presented, and effects of analog link quality on LTE/LTE-A signal is investigated. The EVM measurement after transmission of LTE-A signal with various numbers of intermediate frequency over 20 km SMF link is also presented.

Dual-carrier DQPSK based 112 Gb/s signal transmission over 480 km of SMF link carrying 10 Gb/s NRZ channels

We propose and demonstrate a cost-effective 112 Gb/s optical transceiver based on dual carrier-DQPSK with direct detection. The performances of DC-DQPSK are evaluated by transmitting 112 Gb/s signal over 480 km of SMF link carrying 10 Gb/s NRZ neighboring channels.

Field Trial of 112 Gb/s Dual-Carrier DQPSK Channel Upgrade in Installed 516 km of Fiber Link and ROADM

A field trial of 100GE signal transmission using dual-carrier differential quadrature phase shift keying (DC-DQPSK) based optical transceiver is demonstrated for 100 Gb/s metro area network. Neither high-end ADC/DSP nor fast optical polarization tracking is required in the DC-DQPSK based optical transceiver, which results in low electrical power consumption of ~ 35 W. The measured OSNR sensitivity of DC-DQPSK optical transceiver at the BER of 10- 3 is 18.3 dB. After the transmission through 516 km of installed fiber and ROADM, an error-free transmission of 100GE signal over 106 hours with OTU4 framer and forward error correction (FEC) decoding proves feasibility of DC-DQPSK optical transceiver for 100G metro network applications.

Identification method of non-reflective faults based on index distribution of optical fibers.

This paper investigates an identification method of non-reflective faults based on index distribution of optical fibers. The method identifies not only reflective faults but also non-reflective faults caused by tilted fiber-cut, lateral connector-misalignment, fiber-bend, and temperature variation. We analyze the reason why wavelength dependence of the fiber-bend is opposite to that of the lateral connector-misalignment, and the effect of loss due to temperature variation on OTDR waveforms through simulation and experimental results. This method can be realized by only upgrade of fault-analysis software without the hardware change, it is, therefore, competitive and cost-effective in passive optical networks.

A cost-effective and compact 28-Gb/s ROSA module using a novel TO-CAN package

In this paper, we present the implemented a 28-Gb/s a receiver optical sub-assembly (ROSA) module by employing the proposed TO-CAN package and flexible printed circuit board (FPCB). We have proposed that signal path between the TO-CAN package and the FPCB have straight-line path and the FPCB incorporate signal line with open stub in order to alleviate signal distortion due to impedance mismatch. The 3-dB optical-to-electrical (O-E) bandwidth and receiver sensitivity of the ROSA module were measured as over 17 GHz and below -14 dBm at extinction ratio of 12 dB and bit error rate of 10-12.

Compactly packaged monolithic four-wavelength VCSEL array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport

We report a cost-effective transmitter optical sub-assembly using a monolithic four-wavelength vertical-cavity surface-emitting laser (VCSEL) array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport using the data rate of common public radio interface option 6. The wavelength spacing is achieved using selectively etched cavity control layers and fine current adjustment. The differences in operating current and output power for maintaining the wavelength spacing of four VCSELs are <1.4 mA and <1 dB, respectively. Stable operation performance without mode hopping is observed, and error-free transmission under direct modulation is demonstrated over a 20-km single-mode fiber without any dispersion-compensation techniques.