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We demonstrate a compact terahertz source based on a bimodal laser diode and a plasmonic photomixer, which generates 0.45 mW power at 1.62 THz and offers a broad radiation frequency tuning range of 0.15–3 THz.
We demonstrate Tbit/s transmission with a Q-Dash mode-locked laser using coherent detection. The aggregate capacity achieved with PDM-QPSK was 1.8Tb/s over 50km of SSMF, using 36 channels from the 34.5GHz FSR Q-Dash PMLL.
Advanced wavelength-division multiplexing (WDM) requires both efficient multi-wavelength light sources to generate optical carriers and highly scalable photonic-electronic interfaces to encode data on these carriers. In this paper, we give an overview on our recent progress regarding silicon-organic hybrid (SOH) integration and comb-based WDM transmission.
Chip-scale frequency comb sources are likely to become key elements of future terabit/s optical transceivers. We investigate and demonstrate the viability of different comb generation schemes for transmission at multi-terabit/s data rates.
InAs/ InP quantum dash based mode locked lasers are particularly suited for frequency comb generation. Multi-terabit/s data transmission has been achieved using one single chip.
A real-time 5×21.6 Gbit/s WDM electro-optical transceiver is presented. Optical carriers were spaced by 20 GHz and each one transmitted four orthogonally overlapping broadband subcarriers. Only analogue electronics were employed, achieving an unprecedented spectral efficiency in DSP-less SCM links.
We report on the use of a SOA for simultaneous amplification of multicarrier, 10×12.5 Gb/s, DWDM-SSB-OFDM downstream signals finding negligible penalty at FEC limit compared to EDFAs. The scheme allows for a 128 passive split and transmission over 50 km.
Phase noise measurements have been made on a free-running discrete mode laser diode operating at 1550 nm. We demonstrate emission linewidths as low as 70 kHz at 8.6-mW output power and characterise the device in a 16-QAM transmission setup.
We demonstrate two 1Tbit/s superchannel architectures using a compact, FSR-tunable gain-switched comb source. SSMF transmission of 18GBaud Nyquist-WDM shaped PDM-QPSK and PDM-16QAM modulation is reported, with a capacity up to 1.296Tbit/s and SE of 7.2bit/s/Hz.
The authors investigate and compare the performance of three different optical frequency comb sources in an intensity modulated and directly detected compatible SSB OFDM system. The influence of relative intensity noise and carrier-to-noise ratio of the different multicarrier sources, on the performance of a 12.5 Gb/s compatible SSB OFDM system, were investigated experimentally and by simulation....
We propose a novel technique to measure the correlation between two optical frequencies using a FWM scheme. To verify, we measure the evolution of de-correlation as a function of the path length difference between them.
Future high capacity wavelength division multiplexed (WDM) optical networks will rely on transmitting signals with information encoded on both the amplitude and phase of multiple optical carriers. To optimise the efficiency of these networks, they are likely to employ some level of wavelength switching [1], and a key function required by wavelength switching is wavelength conversion [1]. Wavelength...
Wavelength conversion via four-wave mixing (FWM) schemes of high-bit rate data formats are conventionally achieved using a strong pump source and a secondary nonlinear device, such as highly nonlinear fibre [1] or semiconductor optical amplifier [2]. In this work we obviate the need for a secondary nonlinear device, and achieve wavelength-conversion of high repetition-rate pulse trains by externally...
Widely tunable lasers are expected to be used in coherent optical communications as primary laser sources for a more agile optical network. Sampled grating distributed Bragg reflector (SGDBR) lasers have been proven to be a good candidate for these applications. SGDBR lasers, which are multi-section lasers, exhibit a more complex linewidth broadening than fixed-wavelength semiconductor lasers1. To...
Directly modulated lasers provide simple, and cost efficient, optical transmitters for use in optical networks. However, chirp limits the bit rate distance product achievable in such systems, with transmission distances limited to around 10 km when operating at 10 Gbit/s in the 1550 nm window [1, 2], and thereby limiting their suitability as optical transmitters in next generation access networks...
We demonstrate for the first time a detailed phase noise characterization of Y-branch lasers. BER tests of 10.7GBaud DQPSK revealed the effect of phase noise at frequencies around the relaxation oscillation peak on system performance.
We demonstrate the tracking of white-FM noise and 1/fα excess noise from a SGDBR laser in a coherent system. The performance of 2nd-order phase-locked loop was experimentally examined in 16-QAM system at 16 Gbaud.
We demonstrate a simple method of flexible optical frequency comb generation by gain switching an externally injected DFB laser. The FSR tunability from 25-33GHz renders this transmitter as a potential source for >100Gb/s optical networks.
We experimentally show optically filtered lasers reduce OSNR penalty due to phase tracking error up to 3 dB for two parallel decision directed algorithms with feedback delay in an 11 Gbaud/s 16QAM coherent system.
Coherent communications have become a commercial reality with the deployment of 40 G and 100 G systems using Quadrature Phase Shift Keying (QPSK) in the core network. In the next evolution of these systems higher order modulation formats have the potential to significantly increase capacity while maintaining the baud rate at levels which allow the use of readily available lower cost electro-optics...
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