Low-Noise Operation of Mid-Infrared Quantum Cascade Lasers Using Injection Locking

Quantum cascade lasers are the most promising optical source for emission in the mid-infrared and THz region, and they are already used in a large number of applications such as free-space communications, absorption spectroscopy, sensing and so on. In all these applications, the noise properties of the optical sources are critical for the system performance. In this work, the authors present a theoretical study on the intensity noise characteristics of quantum cascade lasers (QCLs) under external non-coherent optical injection. The injection locking has been proven in the past beneficial for noise properties of bipolar lasers, and thus this technique is utilized here in quantum cascade lasers. With the help of various analytical and numerical models, it is shown that intensity noise reduction can be achieved in the operation of the so-called locked slave laser compared to its free-running values. The detailed analysis reveals the contribution of the various noise sources to the intensity noise of the laser and how they affect the injection locking process. Using different numerical models, two distinct schemes are investigated, analysed and discussed, injection on the lasing mode or on non-lasing residual modes of the slave laser cavity

Line shape in the mirage experiment

Using a many-body theory, we calculate the change in differential conductance dI/dV after adding an impurity either on a clean surface or inside an elliptic quantum corral. Using the same set of parameteres for both cases, the qualitative features of the voltage dependence of the change in dI/dV observed in recent experiments, are reproduced.Comment: 4 pages, 1 combined figure, submitted for the Proceedings of the PASI conference on Physics and Technology at the Nanometer Scale, Costa Ric

All-Optical Regeneration Based on Phase-Sensitive Nondegenerate Four-Wave Mixing in Optical Fibers

An optical regeneration scheme based on nondegenerate phase-sensitive amplification in highly nonlinear fibers is numerically investigated. The proposed regenerator exhibits significant amplitude and phase noise suppression properties and eliminates the need for precise phase and frequency locking with the input return-to-zero differential phase-shift keying signal

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.Peer ReviewedPostprint (published version

Colorless Regenerative Amplification of Constant Envelope Phase-Modulated Optical Signals Based on Injection-Locked Fabry–Pérot Lasers

An efficient phase preserving amplitude noise limiter suitable for constant envelope phase-modulated signals is experimentally demonstrated for 10-Gb/s differential phase-shift-keying (DPSK) signals exploiting injection locking in Fabry–Pérot lasers. The limiter operates successfully over a 16.4-nm tuning range leading to 12 dB of power penalty reduction for 10^-3 of bit-error-rate (BER) performance

Spatial Photonic Reservoir Computing based on Non-Linear Phase-to-Amplitude Conversion in Micro-Ring Resonators

We present a photonic reservoir computing, relying on a non-linear phase-to-amplitude mapping process, able to classify in real-time multi-Gbaud time traces subject to transmission effects. This approach delivers an all-optical, low-power neuromorphic dispersion compensator.Comment:

Pseudo-Random Generator based on a Photonic Neuromorphic Physical Unclonable Function

In this work we provide numerical results concerning a silicon-on-insulator photonic neuromorphic circuit configured as a physical unclonable function. The proposed scheme is enhanced with the capability to be operated as an unconventional deterministic pseudo-random number generator, suitable for cryptographic applications that alleviates the need for key storage in non-volatile digital media. The proposed photonic neuromorphic scheme is able to offer NIST test compatible numbers with an extremely low false positive/negative probability below 10-14. The proposed scheme offers multi-functional capabilities due to the fact that it can be simultaneously used as an integrated photonic accelerator for machine-learning applications and as a hardware root of trust.Comment: 8 pages, 7 figure

Intermixed Time-Dependent Self-Focusing and Defocusing Nonlinearities in Polymer Solutions

[Image: see text] Low-power visible light can lead to spectacular nonlinear effects in soft-matter systems. The propagation of visible light through transparent solutions of certain polymers can experience either self-focusing or defocusing nonlinearity, depending on the solvent. We show how the self-focusing and defocusing responses can be captured by a nonlinear propagation model using local spatial and time-integrating responses. We realize a remarkable pattern formation in ternary solutions and model it assuming a linear combination of the self-focusing and defocusing nonlinearities in the constituent solvents. This versatile response of solutions to light irradiation may introduce a new approach for self-written waveguides and patterns