Heng-Sheng Su

Generation and Transmission of BB/MW/MMW Signals by Cascading PM and MZM

A bidirectional three-band lightwave transport system is proposed and experimentally demonstrated for both fiber-to-the-X (FTTX) and radio-over-fiber (RoF) networks. By cascading a phase modulator (PM) and a Mach-Zehnder modulator (MZM) to generate multiple coherent lightwaves, hybrid 1.25 Gbps baseband (BB), 1.25 Gbps/20 GHz microwave (MW), and 1.25 Gbps/40 GHz millimeter-wave (MMW) downstream signals and a 1.25 Gbps BB upstream signal are simultaneously transmitted. Furthermore, with an assistance of an optical signal-to-noise ratio (OSNR) enhancement circuit, sufficient low bit error rate (BER) values are experimentally achieved for both down-link BB/MW/MMW and up-link BB signals. No additional high-frequency local oscillator, mixers and upstream laser diode are required in both transmitter and receiver sites. Under this architecture, both wire-lined and wireless clients can be simultaneously served without using any extra device/equipment to convert the downstream signals among BB, MW and MMW formats.

A broadband ASE light source-based full-duplex FTTX/ROF transport system

A full-duplex fiber-to-the-X (FTTX)/radio-over-fiber (ROF) transport system based on a broadband amplified spontaneous emission (ASE) light source is proposed and demonstrated for rural wide-spread villages. Combining the concepts of long-transmission transmission and ring topology, a long-haul single-mode fiber (SMF) trunk is sharing with multiple rural villages. Externally modulated baseband (BB) (1.25 Gbps) and radio-frequency (RF) (622 Mbps/10 GHz) signals are successfully transmitted simultaneously. Good bit error rate (BER) performance was achieved to demonstrate the practice of providing wire/wireless connections for long-haul wide-spread rural villages. Since our proposed system uses only a broadband ASE light source to achieve multi-wavelengths transmissions, it also reveals an outstanding one with simpler and more economic advantages.

An Upconverted Phase-Modulated Fiber Optical CATV Transport System

A fiber optical CATV transport system that employed an upconverted technique and a phase modulation scheme to reduce noise and distortion induced by system is proposed and experimentally demonstrated. In contrast to a fiber optical CATV transport system that used a conventional intensity modulation scheme, excellent performances of carrier-to-noise ratio, composite second order, and composite triple beat are obtained in our proposed systems over a 100-km single-mode fiber transmission. It verifies the feasibility of the proposed systems and reveals an outstanding one with excellent transmission performances.

Integration of FTTH and GI-POF in-house networks based on injection locking and direct-detection techniques

An integration of fiber-to-the-home (FTTH) and graded-index plastic optical fiber (GI-POF) in-house networks based on injection-locked vertical cavity surface emitting lasers (VCSELs) and direct-detection technique is proposed and experimentally demonstrated. Sufficient low bit error rate (BER) values were obtained over a combination of 20-km single-mode fiber (SMF) and 50-m GI-POF links. Signal qualities satisfy the worldwide interoperability for microwave access (WiMAX) requirement with data signals of 20 Mbps/5.8 GHz and 70 Mbps/10 GHz, respectively. Since our proposed network does not use sophisticated and expensive RF devices in premises, it reveals a prominent one with simpler and more economic advantages. Our proposed architecture is suitable for the SMF-based primary and GI-POF-based in-house networks.

RoF transport systems with OSNR enhanced multi-band optical carrier generator

A combination of an economic multi-band optical carrier generator and a novel optical signal to noise ratio (OSNR) enhancement circuit is proposed and demonstrated for radio over fiber (RoF) transport systems. Different from normal RoF transport systems which a central station (CS) needs multiple dedicate wavelength laser diodes (LDs) to support various base stations (BSs), the proposed scheme can employ a single LD to provide multiple optical carriers for various BSs. To verify this scheme, 8 coherent optical carriers are firstly generated using a single LD and a local oscillator (LO). Subsequently, their OSNR values are optimized by the developed OSNR enhancement circuit. An up to 15 dB OSNR enlargement in those optical carriers is experimentally achieved. To demonstrate the practice of the proposal, a pair of those optical carriers is employed to experimentally achieve frequency up-conversion process in a RoF transport system. Clear eye diagram and error free transmission reveal that with a proper carrier selector the proposed scheme can be employed to support multiple RoF transmissions. Furthermore, this proposal also presents a high possibility to achieve 60 GHz RoF transmission using a 10 GHz LO, a LD and a low frequency external modulator.

Hybrid CATV/16-QAM OFDM in-building networks over SMF and GI-POF transport

A hybrid CATV/16-QAM OFDM in-building network over a combination of single-mode fiber (SMF) and graded-index plastic optical fiber (GI-POF) transport is proposed and experimentally demonstrated with good qualities of service. In this system, a 1556 nm optical signal is directly transmitted along with two fiber spans (20-km SMF + 25-m GI-POF). Without using any wavelength conversion or bridge circuit between SMF and POF connection, error free transmissions with sufficient low bit error rate (BER) values are achieved for 2.5 Gbps/2.5 GHz and 5 Gbps/2.5 GHz OFDM signals; as well as good performances of carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple beat (CTB) are obtained for CATV one. This proposed network reveals an outstanding one with economy and convenience to be installed.

Integrating Fiber-to-the-Home and POF In-Door Routing CATV Transport System

An integrating fiber-to-the-home and plastic optical fiber (POF) in-door routing CATV transport system is proposed and demonstrated with good quality of service. In this system, a 1550 nm optical signal is directly transmitted along with a span of single-mode fiber (SMF) plus POF without wavelength converting or any bridge circuit. The feasibility of our proposed system is observed and accompanied with good carrier-to-noise ratio, composite second-order, and composite triple beat performances under various SMF and POF lengths. To be the first one, to the best of our knowledge, of successfully transporting CATV signals in such integrated access and in-door LAN, this system reveals prominence in simplicity and cost-effective to provide all-optical CATV service all the way to consumer in-door devices.

Fiber optical CATV transport systems based on PM and light injection-locked DFB LD as a duplex transceiver

A bidirectional optical CATV transport system is proposed with an assistant of frequency-upconversion technique and a phase-modulation scheme to optimize transmission performance as well as an injection-locked DFB LD to work as a duplex transceiver.A bidirectional fiber optical CATV transport system employing phase modulation (PM) scheme and frequency up-conversion technique to deal with downstream CATV signals, and using light injection-locked distributed feedback laser diode (DFB LD) as a duplex transceiver at the receiving site is proposed and experimentally demonstrated. With optimum injection wavelength and power level, a DFB LD is efficiently employed for both the transmitter and receiver operations. Such DFB LD is used to replace the functions of delay interferometer (DI) and CATV receiver, and also to be as the upstream light source. To the best of our knowledge, it is the first time to successfully utilize a DFB LD to detect the phase-modulated CATV signals. Impressive experimental results prove that our proposed systems not only can employ the PM scheme and the frequency up-conversion technique to optimize the overall performances of systems, but also can use an injection-locked DFB LD to detect the downstream phase-modulated CATV signals as well as to transmit the upstream CATV ones simultaneously.

A Radio-Over-GI-POF Transport System

A novel radio-over-graded index-plastic optical fiber (GI-POF) transport system is proposed based on vertical-cavity surface-emitting lasers (VCSELs) and light injection-locking technique. Comparing with other light sources, VCSEL provide a good balance between its cost and quality for intrabuilding network applications. To further enhance its transmission performance, we are the first one to integrate VCSELs with light injection-locking technique in radio-over-GI POF intrabuilding network. Impressive upgrading of third-order intermodulation distortion to carrier ratio, spurious-free dynamic range, error vector magnitude, and bit error rate were experimentally obtained and discussed in the paper.

Down-Link CATV/FTTH and Up-Link FTTH Transport Systems Based on Reflective Semiconductor Optical Amplifier

A down-link CATV/fiber-to-the-home (FTTH) and uplink FTTH transport system employing a reflective semiconductor optical amplifier (RSOA) as wavelength reuse and remodulation schemes is proposed and experimentally demonstrated. By using −1 side mode injection-locked/optoelectronic feedback techniques, brilliant performances of carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple beat (CTB), and bit error rate (BER) were obtained for downlink transmission; low BER value was also achieved for up-link transmission over a 50-km single-mode fiber (SMF) transmission. Such a CATV/FTTH transport system is suitable for broadband access fiber networks.