Adaptive quantised feedback equalisation for FSK heterodynetransmission at 150 Mbit/s and 1 Gbit/s

An adaptive quantised feedback equaliser has been used in an FSK heterodyne receiver to overcome the nonuniform frequency modulation response of a DFB laser transmitter in FSK transmission experiments at 150 Mbit/s and 1 Gbit/s with fibre spans of 121 km and 136 km, respectively     

Over 300 km transmission experiment on an optical FSK heterodyne dual filter detection system

An optical FSK heterodyne dual filter detection system has been developed for the first time at 34 Mbit/s bit rate with a high receiver sensitivity of -61.4 dBm. A 66.9 dB large span loss margin has been achieved with high transmitted power and high receiver sensitivity. As a result, a 301 km transmission experiment has been performed.     

System design and long-span transmission experiments on an optical FSK heterodyne single filter detection system

The influence of LD phase noise on a heterodyne noncoherent detection system was evaluated. Based on the evaluation, an optical FSK heterodyne single filter detection system with large frequency deviation and wide-band IF filter has been developed to allow use of stand-alone DFB LD's. In the system, a phase tunable DFB LD was used as an FSK transmitter light source to improve the FSK modulation characteristics. An IF filter with appropriate bandwidth evaded the influence of LD phase noise. With these configurations, long-span (243 km at 140 Mbit/s and 204 km at 280 Mhit/s) transmission experiments have been successfully carried out on this single filter detection system. To the contrary, influence of LD phase noise appeared in a limited IF bandwidth case, which agrees well with the theoretical evaluation.     

Novel optical FSK heterodyne single filter detection system using a directly modulated DFB-laser diode

A novel optical FSK heterodyne single filter detection system, which can use direct modulation and can tolerate the relatively large spectral width of a laser diode, is proposed. The receiver sensitivity improvement, as much as 8 dB over direct detection using a Ge APD, has been achieved after 105 km transmission at 100 Mbit/s.     

Stabilisation of heterodyne receiver sensitivity with automatic polarisation control system

A low-insertion-loss automatic optical fibre polarisation control system with low driving voltage and low monitoring power has achieved stabilisation of the receiver sensitivity within the fluctuation range of less than 0.4 dB in an optical FSK heterodyne 280 Mbit/s, 141 km transmission experiment.     

Polarisation-insensitive, 500 Mbit/s FSK transmission over 153 km by passive polarisation switching

Polarisation-insensitive heterodyne transmission of a 500 Mbit/s FSK signal over 153 km of fibre is realised by passive, data-induced polarisation switching. For the first time, this technique is used with a delay-line demodulator.<>     

100-channel optical FDM transmission/distribution at 622 Mbit/s over 50 km utilising a waveguide frequency selection switch

100-channel optical FDM transmission/distribution at 622 Mbit/s is demonstrated for a fibre length of 50 km. A polarisation-insensitive waveguide frequency-selection-switch with 10 GHz intervals and an FSK/direct-detection scheme using a Mach-Zehnder filter type optical frequency discriminator are verified as feasible.<>     

546 km, 140 Mbit/s FSK coherent transmission experiment through 10 cascaded semiconductor laser amplifiers

The effect of the spontaneous emission noise on coherent systems in a multistage semiconductor laser amplifier repeater system is experimentally examined. By appropriate adjustment of the input power level to each amplifier, 546 km FSK transmission of 140 Mbit/s using 10 cascaded amplifiers is demonstrated without power penalty.<>     

10 Gbit/s Manchester-encoded FSK-labelled optical signal transmission link

An optical signal consisting of a 10 Gbit/s Manchester-encoded intensity-modulated (IM) payload and a 156 Mbit/s frequency-shift-keying (FSK) label was generated, and its performance was evaluated in an 80 km standard singlemode-fibre link. It is shown that the FSK/IM labelling performance is greatly improved through high-speed Manchester coding.     

Field demonstration of coherent transmission system with diode-pumped erbium doped fibre amplifiers

Reports a field demonstration of 622 Mbit/s DPSK and FSK coherent transmission over 200 km of installed single mode fibre. Diode-pumped erbium doped fibre amplifiers were used as both power amplifiers and repeaters. System loss budgets of more than 68 dB were achieved with an intermediate amplifier repeater gain of 16.5 dB. Both systems incorporated fully automated endless polarisation control.<>     

Transmission experiments through 101 km and 84 km of single-mode fibre at 274 Mbit/s and 420 Mbit/s

Four transmission experiments through low-loss single-mode optical fibre at 1.3 ?m have been performed at 274 Mbit/s and 420 Mbit/s with different objectives. The first demonstrates transmission through 101 km of single-mode fibre at 274 Mbit/s with negligible dispersion penalty. The second experiment at 274 Mbit/s and 84 km uses only components suitable for use in an undersea cable system. Two additional experiments, both at 420 Mbit/s, accomplish a bitrate × distance product of 35 GHzkm with 84 km of fibre and show no dispersion penalty with 63 km and 2.4 ps/km nm dispersion.     

FSK heterodyne transmission experiments at 560 Mbit/s and 1 Gbit/s

Optical frequency-shift-keying (FSK) signals are obtained from directly modulated distributed feedback (DFB) semiconductor lasers. Experimental studies of the direct frequency modulation (FM) characteristics of the DFB lasers show a nonuniform FM response due to the competing effects of thermal modulation of the laser active region and carrier density modulation. Equalization of the signal current to the laser is employed to produce a flat FM response from 30 kHz to 1 GHz. Optical FSK transmission and heterodyne detection experiments at 560-Mbit/s and 1-Gbit/s are conducted at a wavelength of 1497 nm. Receiver sensitivities of -39 dBm at 560 Mbit/s and -37 dBm at 1 Gbit/s are obtained. Transmission through 100 km of single-mode fiber at 1 Gbit/s is achieved with no degradation in receiver sensitivity.     

140 Mbit/s and 560 Mbit/s FSK heterodyne polarisation diversity receiver using nearly perfect square law demodulators

A new frequency discriminator concept with nearly perfect square law demodulation characteristics is described. The performance of the device is verified in a 140 Mbit/s and 560 Mbit/s FSK heterodyne polarisation diversity transmission experiment.<>     

Bidirectional multichannel 1.44 Gbit/s lightwave distributionsystem using subcarrier multiplexing

Demonstrates a bidirectional lightwave distribution system that uses subcarrier multiplexing to transmit data to eight nodes from a single head-end laser. Data for each node (180 Mbit/s) and return date (45 Mbit/s digital video) are transmitted as FSK subcarrier, between 2.5 and 5.0 GHz. Penalties from laser nonlinearities, interchannel interference or bidirectional transmission are negligible     

500 Mbit/s transmission experiment using 1.3 ?m wavelength InGaAsP/InP high-speed surface-emitting DH LEDs

A 1.3 ?m-wavelength high-speed surface-emitting DH LED, with 0.6 ns rise time and 1.3 ns fall time, has been developed by optimal design of both the LED parameters and driving circuit. A 500 Mbit/s RZ pseudorandom pulse transmission experiment using the high-speed DH LED has been performed with a 5.7 dB level margin over a 2.7 km optical fibre. The 500 Mbit/s LED system feasibility has been confirmed.     

Investigation on the combined orthogonal FSK/ASK labeled signal based on cross gain modulation in a SOA

An optical frequency shift keying(FSK) transmitter performed by the cross gain modulation(XGM) in a semiconductor optical amplifier(SOA) is used in an optical label switching(OLS) system with 622 Mbit/s FSK label and 10 Gbit/s amplitude shift keying(ASK) payload.The key parameters in this system are optimized to achieve the best performance of FSK/ASK signal,including the input power of LD,the extinction ratio(ER) of the control light and that of the ASK payload.Besides,the transmission performance of ASK p...     

400 Mbit/s CMI transmission experiment using a 1.3 ?m LED

A 400 Mbit/s CMI optical transmission experiment has been successfully conducted, using an LED, a GI multimode fibre and a 250 MHz bandwidth monolithic equalising amplifier. In this experiment, 5 km transmission distance has been achieved. The transmission characteristics and required transmission bandwidth are reported.     

An Experimental 800 Mbit/s Four-Level Repeater Compatible with the 60 MHz Analog System

The design and performance of an experimental 800 Mbit/s repeater for four-level digital transmission over a coaxial cable is described in this paper. The 800 Mbit/s digital system exceeds the 60 MHz analog system, both in capacity and in economy. The repeater is designed to operate in repeater housings located at 1.6 km maximum spacing to be compatible with the 60 MHz analog sytsem. A nonredundant four-level line code has been employed, using a newly developed quantized feedback dc restoration technique. The most important item in realizing the high-speed multilevel repeater is the reduction of intersymbol interference. A simple quantized feedback scheme and an adjustable three-tap transversal equalizer have been used to compensate for intersymbol interference. The experimental repeater has been tested for 1.1-1.7 km repeater spacings using 2.6/9.5 mm coaxial cable. The results show that an 800 Mbit/s repeater with 1.6 km maximum repeater spacing is feasible.     

Injection-locked 1.5 ?m InGaAsP/InP lasers capable of 450 Mbit/s transmission over 106 km

The fluctuation of longitudinal modes of a high-bit-rate modulated 1.5 ?m InGaAsP/InP laser is greatly improved by injection-locking technology. A 106 km transmission at 300 Mbit/s and 450 Mbit/s was achieved with tolerable transmission losses of 37.2 dB and 36.2 dB, respectively, which implies a potential transmission distance of over 145 km.