Active coherent beam combining and beam steering using a spatial mode multiplexer

Coherent beam combination is one promising way to overcome the power limit of one single laser. In this paper, we use a Multi-Plane Light Converter to combine 12 fibers at 1.03 micron with a phase locking setup. The overall loss measurement gives a combination efficiency in the fundamental Hermite-Gaussian mode as high as 70%. This setup can generate the fundamental and higher-order Hermite-Gaussian modes and has beam steering capabilities

Silicon-on-Insulator RF Filter Based on Photonic Crystal Functions for Channel Equalization

International audienceA compact silicon-on-insulator 2-tap interferometer is demonstrated as a channel equalizer. The radiofrequency filter is reconfigurable thanks to thermally-controlled photonic crystal couplers and delay lines. The channel fading of a dispersive fiber link supporting a directly modulated telecommunication signal is successfully compensated for using the interferometer, leading to eye diagram opening and the possibility to recover the bit-error-rate of a reference signal with less than 1-dB power penalty

Silicon photonics frequency shifter based on I&Q dual Mach-Zehnder modulator

We present a fully CMOS compatible frequency shifter device, in a I&Q dual Mach-Zehnder architecture. Frequency shift up to 410 MHz are obtained, with carrier and image sideband extinction from 27 to 51 dB

Time delay generation at high frequency using SOA based slow and fast light

International audienceWe show how Up-converted Coherent Population Oscillations (UpCPO) enable to get rid of the intrinsic limitation of the carrier lifetime, leading to the generation of time delays at any high frequencies in a single SOA device. The linear dependence of the RF phase shift with respect to the RF frequency is theoretically predicted and experimentally evidenced at 16 and 35 GHz. (C) 2011 Optical Society of Americ

Influence of optical filtering on nonlinearities in SOA-based slow and fast light microwave phase shifter

International audienceWe present an experimental and numerical investigation of the influence of filtering the red-shifted modulation on the linearity of a microwave-photonics link with a CPO-based phase shifter. Different behavior versus SOA bias current are evidenced

Experimental ARoF System Based on OPLL Mm-Wave Generation for Beyond 5G

We experimentally analyze the ARoF based on OPLL mm-Wave generation performance for 5G fronthaul. Remarkable performance improvements are achieved for all 5G NR numerologies and different OPLL configurations despite their inherently high phase noise level

Optical phase-locked loop phase noise in 5G mm-wave OFDM ARoF systems

The use of millimeter-wave (mm-wave) frequencies is required in order to support the increasing number of connected devices expected from the fifth generation (5G) of mobile communications. Subsequently, the generation of radio-frequency (RF) carriers ranging from 10 GHz to 300 GHz and their transport through optical distribution network (ODN) is a key element of the future 5G fronthaul. Optically assisted RF carrier generation is one of the most promising solutions to tackle this issue, allowing a wide use of analog radio-over-fiber (ARoF) architectures. However the main limitation of these optical methods is related to the finite coherence of lasers sources, which can dramatically degrade data transmission in analog formats. To mitigate its impact, the use of orthogonal frequency-division multiplexing (OFDM) as the 5G standard allows employing efficient phase noise compensation algorithms. Therefore, in this study, we present an experimental demonstration of a mm-wave generation technique based on an optical phase-locked loop (OPLL) that fulfills the frequency specifications for 5G. Then, an algorithm is introduced that improves data recovery at reception and reduces the impact of a possible high phase noise carrier. Finally, a back-to-back data transmission experiment is performed, demonstrating the efficiency of the algorithm to reach the 5G requirements. These results emphasize the use of OPLLs as a viable solution to generate mm-wave carriers for 5G and beyond

Free Space Intra-Datacenter Interconnects Based on 2D Optical Beam Steering Enabled by Photonic Integrated Circuits

Data centers are continuously growing in scale and can contain more than one million servers spreading across thousands of racks; requiring a large-scale switching network to provide broadband and reconfigurable interconnections of low latency. Traditional data center network architectures, through the use of electrical packet switches in a multi-tier topology, has fundamental weaknesses such as oversubscription and cabling complexity. Wireless intra-data center interconnection solutions have been proposed to deal with the cabling problem and can simultaneously address the over-provisioning problem by offering efficient topology re-configurability. In this work we introduce a novel free space optical interconnect solution for intra-data center networks that utilizes 2D optical beam steering for the transmitter, and high bandwidth wide-area photodiode arrays for the receiver. This new breed of free space optical interconnects can be developed on a photonic integrated circuit; offering ns switching at sub-μW consumption. The proposed interconnects together with a networking architecture that is suitable for utilizing those devices could support next generation intra-data center networks, fulfilling the requirements of seamless operation, high connectivity, and agility in terms of the reconfiguration time

Orbital Angular Momentum beams generation from 61 channels Coherent Beam Combining femtosecond Digital Laser

International audienceWe report on the use of a 61 beamlets Coherent Beam Combination femtosecond fiber amplifiers as a digital laser source to generate high power Orbital Angular Momentum beams. Such approach opens the path for higher order non-symmetrical user-defined far field distributions