Moon-Ki Hong

Gigabit Optical Access Link for Simultaneous Wired and Wireless Signal Transmission Based on Dual Parallel Injection-Locked Fabry–PÉrot Laser Diodes

A novel scheme, for the wired and wireless gigabit data transmission in optical access network, is proposed and experimentally demonstrated by using dual parallel injection locked Fabry-Perot laser diodes. In the proposed method, it was able to achieve both the optical carrier suppressed signals with high suppression ratio and high transmission performance for both baseband and 60-GHz signal by injection locking of each sideband and direct modulation of the Fabry-Perot laser diodes, respectively. Using the remodulation technique based on reflective semiconductor optical amplifier, it was possible to accomplish bidirectional 1.25 Gbps 20-km transmission (BER < 10-9) with the receiver sensitivity lower than - 20 dBm.

20-Gb/s AMO OFDM Transmission Over 20-km Bidirectional Link by Separate I/Q Baseband Delivery Using Remotely Fed 1-GHz RSOAs

We demonstrated a novel 20-Gb/s adaptively modulated optical orthogonal frequency division multiplexed (AMO OFDM) transmission scheme with separate in-phase (I) and quadrature (Q) channel baseband delivery over a 20-km single fiber link using remotely fed 1-GHz reflective semiconductor optical amplifiers (RSOAs) for a colorless optical network unit (ONU). The OFDM symbols with adaptive bit-/power-loading were applied to overcome the bandwidth limitation of RSOAs and to optimize the performance. In order to realize the baseband transmission without Hermitian symmetry, the I and Q channel data streams in the OFDM symbols were separately transmitted by optical carriers at two different wavelengths. Our proposed scheme was experimentally validated using a periodic property of free spectral range (FSR) in a wavelength multiplexer. The separate optical “dual” carriers were provided by the same port of the wavelength multiplexer to avoid wasting the number of wavelength division multiplexed channels.

Linearization of DFB LD by using Cross Gain Modulation of Reflective SOA in Radio-over-Fiber Link

We proposed a novel linearization technique for a DFB LD in the RoF link. The proposed scheme is based on the cross gain modulation(XGM) effect of a reflective semiconductor optical amplifier(RSOA) with light injection. We experimentally demonstrated and evaluated the enhanced CIR performance using the proposed linearization scheme.

Colorless two different gigabit data access transmissions using optical double sideband suppressed carrier and optical sideband slicing

A wavelength division multiplexed (WDM) radio over fiber access network architecture, capable of simultaneously transmitting both 63 GHz wireless and 2.5 Gb/s wired data, is proposed in this paper. An optical carrier suppression effect and multiplexing of a 50 GHz spaced arrayed waveguide grating are employed to generate a 63 GHz millimeter-wave signal based on WDM. These techniques allow the proposed scheme to simultaneously transmit both wireless and wired data. For full colorless operation, a reflective semiconductor optical amplifier is used at the central office and base station. Error-free simultaneous transmissions [wired data: bit error rate (BER) of 10-12, wireless data: BER of 10-9] of 2.5 Gb/s wired data and 1.25 Gb/s wireless data are achieved. Various impacts of the downlink transmission on the performance of uplink data are investigated with the proposed scheme.

Gain-Saturated Reflective Semiconductor Optical Amplifier Cascaded Electroabsorption Transceiver for Enhanced Remote Node Performance

A novel remote node (RN) scheme based on gain saturated reflective semiconductor optical amplifier (GS-RSOA) cascaded electroabsorption transceiver (EAT) is presented for linearization and reduction of dispersion induced carrier suppression (DICS) for uplink transmission. The help of gain saturation property of RSOA, the transfer curve of EAT can be linearized and transmission performance can be robust from DICS. By using the proposed scheme, carrier to interference ratio (CIR) was enhanced by 10.7 dB at the 10 GHz frequency band and 33.4 dB gain of 5.65 GHz RF frequency was measured for 75.6 km data transmission.

Gigabit radio-over-fiber link for converged baseband and millimeter-wave band signal transmission using cascaded injection-locked Fabry-Pérot laser diodes

A novel scheme, for both baseband and millimeter-wave band gigabit data transmission in radio-over-fiber system, is proposed and experimentally demonstrated by using cascaded injection-locked Fabry- Pérot laser diodes. It was able to improve suppression ratio of carrier suppressed signal using the cascaded injection-locking. The suppression ratio improvement of the optical carrier suppressed signal of 20 dB was verified. Applying this mechanism, 60-GHz millimeter-wave carrier of enhanced signal quality could be accomplished. Its peak power and phase noise were obtained as -40 dBm and -103.5 dBm/Hz respectively, which was suitable for 60-GHz data transmission. In addition, a successful bidirectional transmission of 1.25-Gbps wired and wireless data was achieved by adopting remodulation technique using a gain-saturated reflective semiconductor optical amplifier for uplink.

Slow Adaptive OFDMA-PON Through Channel Stabilization Employing Seed Carrier Clipping

We have proposed and experimentally demonstrated a novel slow adaptive orthogonal frequency division multiple access (OFDMA)-based passive optical network (PON) with a single-fiber loopback link. The proposed slow adaptive OFDMA-PON is realized by employing a clipping modulation of an optical seed carrier, which is fed to uplink transmitters at an optical network unit (ONU) in a carrier distribution scheme. Therefore, a fast changing characteristic of the single-fiber loopback channel, which is mainly attributed to Rayleigh backscattering interference, can be dramatically stabilized. Consequently, the uplink OFDMA-PON transmitters can reduce a large number of signal processing in updating channel state information and relevant subcarrier allocation for multiple access unless the required traffic condition changes for the given ONU.

12-Gbit/s DMT transmission based on 1-GHz RSOA with mitigated rayleigh backreflection employing 10-MHz clipping of optical seed carrier

We propose and experimentally demonstrate a novel transmission technique for 12-Gbit/s DMT in a 20-km single fiber loopback using a 1-GHz RSOA. Rayleigh backreflection noise, which has been a critical obstacle in a single fiber loopback, could be drastically mitigated by employing 10-MHz RF clipping modulation of an optical seed carrier.

19-Gb/s adaptively modulated optical OFDM transmission for WDM-PON using 1 GHz RSOAs with separated I/Q baseband delivery

19Gb/s transmission over 23-km SMF is demonstrated based on 1-GHz bandwidth limited RSOAs with adaptively modulated optical OFDM. A novel baseband transmission technique with in-phase/quadrature channel separation is applied to halve the sampling speed requirements. Selective bit allocation with pre-emphasis and post compensation are used to optimize the transmission performance.

Millimeter-wave generation and bidirectional radio-over-fiber wired/wireless transmission using cascaded injection-locked FP-LDs

A novel scheme of cascaded injection locking, based on Fabry-Perot laser diodes, is proposed to generate millimeter-wave carrier and to implement bidirectional RoF wired and wireless data transmission system. It was verified for the proposed technique to improve a suppression ratio of an optical carrier suppressed signal by 20 dB. There was an achievement of 60 GHz carrier generation which had RF peak power of -40 dBm and phase noise of -103.5 dBm/Hz at 1 MHz offset. In addition, it was possible to support bidirectional 1.25-Gbps wired and wireless transmission by adopting the remodulation of a gain-saturated reflective semiconductor optical amplifier for the uplink.