The provision of both wireless and wired services in the optical access domain will be an important function for future passive optical networks (PON). With the emergence of 5th generation (5G) mobile communications, a move toward a dense deployment of small cell antenna sites, in conjunction with a cloud radio access network (C-RAN) architecture, is foreseen. This type of network architecture greatly increases the requirement for high capacity mobile fronthaul and backhaul links. An efficient way of achieving such connectivity is to make use of wavelength division multiplexed (WDM) PON infrastructure where wireless and wired services may be converged for distribution. In this work, for the first time, the convergence of 5G wireless candidate waveforms with a single-carrier wired signal is demonstrated in a PON. Three bands of universally filtered orthogonal frequency division multiplexing (UF-OFDM) and generalized frequency division multiplexing (GFDM), are transmitted at an intermediate frequency in conjunction with a digital 10Gb/s pulse amplitude modulation (PAM-4) signal in the downlink direction. Orthogonal frequency division multiplexing (OFDM) is also evaluated as a benchmark. Results show, for each waveform, how performance varies due to the 5G channel spacing - indicating UF-OFDM's superiority in terms of PON convergence. Successful transmission over 25km of fibre is also demonstrated for all waveforms.

We report on an InP photonic integrated circuit for the generation of an externally injected gain switched optical frequency comb. The device is fully characterized and generates a comb with frequency spacing ranging from 6 to 10 GHz, good noise properties that include relative intensity noise of < - 130 dB/Hz and linewidth of 1.5 MHz, and a high phase correlation between comb lines. These characteristics, in conjunction with the compactness and cost efficiency of the integrated device, demonstrate the quality of the resultant comb source for numerous applications. (C) 2017 Optical Society of America

Due to the growing popularity of optical superchannels and software-defined networking, reconfigurable optical add-drop multiplexer (ROADM) architectures for superchannel switching have recently attracted significant attention. ROADMs based on micro-electro-mechanical system (MEMS) and liquid crystal-on-silicon (LCoS) technologies are predominantly used. Motivated by requirements for low power, high-speed, small area footprint, and compact switching solutions, we propose and demonstrate spatial and wavelength flexible superchannel switching using monolithically integrated silicon photonics (SiP) micro-ring resonators (MRRs). We demonstrate the MRRs' capabilities and potential to be used as a fundamental building block in ROADMs. Unicast and multicast switching operation of an entire superchannel is demonstrated after transmission over 50 km of standard single mode fiber. The performance of each sub-channel from the 120 Gb/s QPSK Nyquist superchannel is analyzed, and degradation in error vector magnitude performance was observed for outer sub-channels due to the 3 dB bandwidth of the MRRs, which is comparable with the superchannel bandwidth. However, all sub-channels for all switching cases (unicast, multicast, and bi-directional operation) exhibit performance far below the 7% FEC limit. The switching time of the SiP MRR chip is such that high-capacity superchannel interconnects between users can be set up and reconfigured on the microsecond time scale.

Aiming to facilitate increased intra-datacenter throughput and reconfigurability, the use of a programmable silicon photonic chip to achieve optical circuit switching and multicasting of 12.5GBaud burst mode PAM-4 is experimentally demonstrated for the first time.

An optoelectronic terahertz (THz) receiver for heterodyne detection of THz signals as low as 3 μW is demonstrated. To the best of our knowledge, this is the most sensitive optoelectronic heterodyne THz receiver to date. The intermediate frequency (IF) bandwidth of the detector is only limited by the used amplifier. The InGaAs-based photoconductor operating at 1.5 μm allows for a fully fiber-coupled receiver unit. This simplifies its use for spectroscopy and THz communication.

Chip-scale frequency comb sources are key elements for a variety of applications, comprising massively parallel optical communications and high-precision optical metrology. In this talk, we give an overview on our recent progress in the area of integrated optical comb generators and of the associated applications. Our experiments cover modulator-based comb sources, injection locking of gain-switched laser diodes, quantum-dash mode-locked lasers, as well as Kerr comb sources based on cavity solitons. We evaluate and compare the performance of these devices as optical sources for massively parallel wavelength division multiplexing at multi-terabit/s data rates, and we report on comb-based approaches for high-precision distance metrology.

In this paper we demonstrate a reduction of relative-intensity noise of a mode-locked laser and a gain-switched comb source based on external injection employing a novel optical demultiplexer. Significant performance improvement is demonstrated in 3.125GBaud, 12.5GBaud and 28GBaud PAM-4 systems.

We demonstrate a programmable control-plane based on field programmable gate array (FPGA) with a power-efficient algorithm for optical unicast, multicast, and broadcast functionalities in a silicon photonic platform. The platform includes a silicon photonic 1×8 microring array chip which in conjunction with a fast tunable laser over the C-band is capable of delivering software controlled wavelength selective functionality on top of spatial switching. We characterize the thermo-optic response of microring resonators and extract key parameters necessary for the development of the control-plane. The performance of the proposed architecture is tested with 10 Gb/s on-off keying (OOK) optical data and error-free operation is verified for various wavelength and spatial switching scenarios. Lastly, we evaluate electrical power and energy consumption required to reconfigure the silicon photonic device for all possible wavelength operations and output ports combinations and show that unicast, multicast of two, three, four, five, six, seven, and broadcast functions are achieved with energy overheads of 0.02, 0.07, 0.18, 0.49, 0.76, 1.01, 1.3, and 1.55 pJ/bit, respectively.

We demonstrate the performance of a novel integrated gain switched optical frequency comb source (GS-OFCS) in two different optical transmission systems. The device generates a 6.25-GHz frequency spaced comb that comprises eight spectral tones in a 3-dB spectral power ripple. The GS-OFCS presents good noise properties, which include relative intensity noise of ~ -125 dB/Hz and linewidth of 1.5 MHz. We then employ the device in two transmission systems that use advanced modulation formats. First, it is employed in a four-level pulse amplitude modulation format system operating at 3.125-GBaud per channel and over 3 km of standard single mode fiber (SSMF), where all the channels performed below the 7% FEC limit and the receiver sensitivity achieved was -21 dBm. Then, the GS-OFCS is used in a Nyquist quadrature phase-shift keying (QPSK) system at 5-Gbaud per channel and over 50 km of SSMF, where all the channels exhibited a similar performance well below the 7% FEC limit. These results, in conjunction with the compactness and cost efficiency of the integrated device, denote the quality and relevancy of the resultant comb source for future optical transmission systems.

Quantum dash (Q-Dash) passively mode-locked lasers (PMLLs) exhibit significant low frequency relative intensity noise (RIN), due to the high mode partition noise (MPN), which prevents the implementation of multilevel amplitude modulation formats such as PAM4. The authors demonstrate low frequency RIN mitigation by employing 8B/10B and Manchester encoding with PAM4 modulation format. These encoding techniques reduce the overlap between the modulation spectral content and the low-frequency RIN of the Q-dash devices, at the expense of increased overhead. The RIN of the 33.6 GHz free spectral range Q-dash PMLL was characterized, and the results obtained show very high levels of RIN from DC to 4 GHz, but low levels for higher frequencies. The performance improvement for 28 GBaud 8B/10B and Manchester encoded PAM4 signal has been demonstrated compared to the case when no encoding is used. Finally, the effect of RIN on the system performance was demonstrated by comparing the bit error rate (BER) performance of the PAM4 signaling obtained with an external cavity laser (ECL) to those obtained with Q-dash PMLL.

5G communications will require the effective transmission of new radio signals through fiber networks, in order to facilitate the proliferation of antenna sites as well as greater pooling of resources. Next generation optical access networks can provide an efficient platform for mobile x-haul. Techniques discussed in this paper shows how both wired and 5G wireless services may be converged over a single fiber infrastructure, and how optical networking can be harnessed in order to provide flexible millimeter-wave radio-over-fiber.

We demonstrate transmission of a 200-Gb/s superchannel over 3-km single-mode optical fiber (SMF) targeting intra-data center interconnect applications using a novel single-section quantum-well passive-mode-locked laser that generates an optical frequency comb. The transmitted optical signal consists of 16 subcarriers filtered from the optical frequency comb of the laser and modulated with an advanced modulation format of Baudrate-pilot-aided quadrature phase-shift keying (QPSK) modulation that enables direct detection. Bit error rates below the forward error correction limit have been confirmed for all subcarriers, and the detailed noise characteristics of the passive-mode-locked laser have been investigated to support the understanding of the system performance.

Summary form only given. We investigate the amplitude and phase noise of an optical frequency comb based on InAs/InP Quantum-dash (Qdash) mode-locked laser (MLL). The laser demonstrates low relative intensity noise (RIN) and phase noise in the passive regime. By actively mode-locking the laser, we observe a reduction in the 1/f phase noise and timing jitter, as a result of which the optical linewidth decreases. Owing to such low noise performance, the frequency combs generated by Qdash lasers are particularly suited for data center interconnects using coherent optical communication.

We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

We investigate the amplitude and phase noise of an optical frequency comb based on InAs/InP quantum-dash mode-locked laser. The laser demonstrates low relative intensity noise (<-125 dB/Hz) and phase noise in the passive modelocking regime. By actively mode-locking the laser, we observe a reduction in the flicker FM noise and timing jitter, as a result of which the optical linewidth decreases, and hence the effective bandwidth compatible with optical coherent systems increases by more than 50% to similar to 1.1 THz.

We experimentally investigate the corner frequency in the 1/f frequency noise of the longitudinal modes of an InAs/InP quantum-dash based single-section passive mode-locked laser. The corner frequency features a strong asymmetry across the optical frequency comb with the values ranging from 10 MHz in the low-frequency side to 180 MHz in the high-frequency side. Actively mode-locking the laser induces a reduction in the corner frequency as it changes from 3 MHz in the low-frequency side to 70 MHz in the high-frequency side and the asymmetry persists.

Due to the growing popularity of optical superchannels and software defined networking, reconfigurable optical add-drop multiplexer (ROADM) architectures for superchannel switching have recently attracted significant attention. ROADMs based on micro electro-mechanical system (MEMS) and liquid crystal-on-silicon (LCoS) technologies are predominantly used. Motivated by requirements for low power, high-speed, small area footprint and compact switching solutions, we propose and demonstrate spatial and wavelength flexible superchannel switching using monolithically integrated silicon photonics (SiP) micro-ring resonators (MRR). We demonstrate the MRRs capabilities and potential to be used as a fundamental building block in ROADMs. Unicast and multicast switching operation of an entire superchannel is demonstrated after transmission over 50 km of standard single mode fiber. The performance of each sub-channel from the 120 Gb/s QPSK Nyquist superchannel is analyzed and degradation in error vector magnitude performance was observed for outer sub-channels due to the 3-dB bandwidth of the MRRs, which is comparable with the superchannel bandwidth. However, all sub-channels for all switching cases (unicast, multicast and bi-directional operation) exhibit performance far below the 7% FEC limit. The switching time of the SiP MRR chip is such that high capacity superchannel interconnects between users can be setup and reconfigured on the microsecond timescale.

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.

We propose and experimentally demonstrate a long-reach Nyquist ultradense wavelength division multiplexed passive optical network using a tunable optical frequency comb source and a digital coherent receiver. Each of the six comb tones on a 12.5 GHz grid is modulated with a 12 Gbaud Nyquist polarization division multiplexed quadrature phase shift keyed signal which includes a 20% overhead for forward error correction. Unrepeated downlink transmission of 100 km is demonstrated at three different operating wavelengths across the C-band. A worst-case channel sensitivity of -35.3 dBm (59 photons/bit) is achieved at a bit error rate of 1.5 x 10(-2), yielding a system loss budget of 35.7 dB.