[Show abstract][Hide abstract] ABSTRACT: We propose an on-chip optical architecture to support massive parallel communication among high-performance spiking laser neurons. Designs for a network protocol, computational element, and waveguide medium are described, and novel methods are considered in relation to prior research in optical on-chip networking, neural networking, and computing. Broadcast-and-weight is a new approach for combining neuromorphic processing and optoelectronic physics, a pairing that is found to yield a variety of advantageous features. We discuss properties and design considerations for architectures for scalable wavelength reuse and biologically relevant organizational capabilities, in addition to aspects of practical feasibility. Given recent developments commercial photonic systems integration and neuromorphic computing, we suggest that a novel approach to photonic spike processing represents a promising opportunity in unconventional computing.
Journal of Lightwave Technology 11/2014; 32(21). · 2.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose and experimentally demonstrate a wavelength-division multiplexed (WDM) optical stealth transmission system carried by amplified spontaneous emission (ASE) noise. The stealth signal is hidden in both time and frequency domains by using ASE noise as the signal carrier. Each WDM channel uses part of the ASE spectrum, which provides more flexibility to apply stealth transmission in a public network and adds another layer of security to the stealth channel. Multi-channel transmission also increases the overall channel capacity, which is the major limitation of the single stealth channel transmission based on ASE noise. The relations between spectral bandwidth and coherence length of ASE carrier have been theoretically analyzed and experimentally investigated.
[Show abstract][Hide abstract] ABSTRACT: A novel highly scalable adaptive photonic beamformer is proposed and experimentally verified. A single-mode-to-multimode combiner allows our system to recycle the same set of wavelengths for each antenna in the array. A “blind” search algorithm called the guided accelerated random search (GARS) algorithm is shown. A maximum cancellation of ∼37 dB is achieved within 50 iterations, while the presence of a signal of interest (SOI) is maintained. Cancellation across the 900 MHz and 2.4 GHz bands are shown to prove the broadband nature of the optical beamformer.
Journal of Lightwave Technology 10/2014; 32(20):3623-3629. · 2.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: System performance of optical steganography is theoretically analyzed and experimentally demonstrated. The optical stealth channel is carried by amplified spontaneous emission noise, which hides the stealth data in both the time and frequency domain. Meanwhile, because the stealth channel uses noise as the signal carrier, the relation between signal-to-noise ratio (SNR) and carrier power is fundamentally different from the traditional optical channels carried by modulating lasers. To transmit and hide the stealth signal in the existing public network, the degradation principle of SNR of the stealth channel is studied. Such principle can guide the design of the stealth transmission system and optimize the carrier power of the stealth channel.
[Show abstract][Hide abstract] ABSTRACT: We propose an equivalent circuit model for photonic spike processing laser
neurons with an embedded saturable absorber---a simulation model for photonic
excitable lasers (SIMPEL). We show that by mapping the laser neuron rate
equations into a circuit model, SPICE analysis can be used as an efficient and
accurate engine for numerical calculations, capable of generalization to a
variety of different laser neuron types found in literature. The development of
this model parallels the Hodgkin--Huxley model of neuron biophysics, a circuit
framework which brought efficiency, modularity, and generalizability to the
study of neural dynamics. We employ the model to study various
signal-processing effects such as excitability with excitatory and inhibitory
pulses, binary all-or-nothing response, and bistable dynamics.
[Show abstract][Hide abstract] ABSTRACT: An optical encryption method based on analog noise is proposed and experimentally demonstrated. The transmitted data is encrypted with wideband analog noise. Without decrypting the data instantly at the receiver, the data is damaged by the noise and cannot be recovered by post-processing techniques. A matching condition in both phase and amplitude of the noise needs to be satisfied between the transmitter and the receiver to cancel the noise. The precise requirement of the phase and amplitude matching condition provides a large two-dimensional key space, which can be deployed in the encryption and decryption process at the transmitter and receiver.
[Show abstract][Hide abstract] ABSTRACT: We propose an optical encryption technique where the data is encrypted with wideband analog noise. Matching both the phase and amplitude of the noise is required, providing a large key space for the encryption process.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate a photonic coincidence detection circuit with a graphene excitable laser. This technology is a potential candidate for applications in novel all-optical devices for information processing and computing.
[Show abstract][Hide abstract] ABSTRACT: The marriage of two vibrant fields---photonics and neuromorphic
processing---is fundamentally enabled by the strong analogies within the
underlying physics between the dynamics of biological neurons and lasers, both
of which can be understood within the framework of nonlinear dynamical systems
theory. Whereas neuromorphic engineering exploits the biophysics of neuronal
computation algorithms to provide a wide range of computing and signal
processing applications, photonics offer an alternative approach to
neuromorphic systems by exploiting the high speed, high bandwidth, and low
crosstalk available to photonic interconnects which potentially grants the
capacity for complex, ultrafast categorization and decision-making. Here we
highlight some recent progress on this exciting field.
IEEE Photonics Society Newsletter. 06/2014; 28(3):4--11.
[Show abstract][Hide abstract] ABSTRACT: We present the design and simulation results for a photonic integrated circuit (PIC) that performs in-channel and broadband radio-frequency self-interference cancellation. The PIC removes interference by modeling channel effects and inverting a known interferer prior to combining it with the corrupted signal. We present key simulation results showing that the PIC can cancel extremely wideband interferers by ~20 dB. The PIC performance can be improved by reducing signal attenuation and nonlinearities. We plan to fabricate the PIC on a hybrid silicon-on-insulator III-V evanescent photonic platform.
2014 23rd Wireless and Optical Communication Conference (WOCC); 05/2014
[Show abstract][Hide abstract] ABSTRACT: A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase.
[Show abstract][Hide abstract] ABSTRACT: We propose and experimentally demonstrate a method for generating and sharing a secret key using phase fluctuations in fiber optical links. The obtained key can be readily used to support secure communication between the parties. The security of our approach is based on a fundamental asymmetry associated with the optical physical layer: the sophistication of tools needed by an eavesdropping adversary to subvert the key establishment is significantly greater and more costly than the complexity needed by the legitimate parties to implement the scheme. In this sense, the method is similar to the classical asymmetric algorithms (Diffie-Hellman, RSA, etc.).
[Show abstract][Hide abstract] ABSTRACT: This letter presents a novel architecture for a wideband photonic beamformer. The system is best suited for an adaptive beamforming application related to a highly non-stationary environment, requiring rapid beam steering. Using optical transversal filters for each antenna element, the array is capable of both spatial beamforming and frequency-domain filtering. With the use of a single-mode fiber to multimode fiber coupling technique, our system is highly scalable, and the same set of laser wavelengths can be used for every antenna in the system. Experimental results are presented to show proof-of-concept and demonstrates proposed adaptive beamformer performance.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate for the first time an excitable laser using graphene. This technology is a potential candidate for applications in novel all-optical devices for information processing and computing.
[Show abstract][Hide abstract] ABSTRACT: We propose an original design for a neuron-inspired photonic computational primitive for a large-scale, ultrafast cognitive computing platform. The laser exhibits excitability and behaves analogously to a leaky integrate-and-fire (LIF) neuron. This model is both fast and scalable, operating up to a billion times faster than a biological equivalent and is realizable in a compact, vertical-cavity surface-emitting laser (VCSEL). We show that-under a certain set of conditions-the rate equations governing a laser with an embedded saturable absorber reduces to the behavior of LIF neurons. We simulate the laser using realistic rate equations governing a VCSEL cavity, and show behavior representative of cortical spiking algorithms simulated in small circuits of excitable lasers. Pairing this technology with ultrafast, neural learning algorithms would open up a new domain of processing.
IEEE Journal of Selected Topics in Quantum Electronics 09/2013; 19(5):1-12. · 3.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel analog optical technique for multipath interference cancellation of broadband signals is proposed. Multiple optical compensation branches are utilized to replicate wireless multipath channel effects. The duplicated signal is subtracted from the total received signal to recover the signal of interest while suppressing interference. The proposed architecture achieved 40 dB of cancellation over 200 MHz and 50 dB over 10 MHz. The depth and broadband nature of the cancellation demonstrates the precision of optical components and the validity of our interference cancellation scheme.
[Show abstract][Hide abstract] ABSTRACT: We report new approaches for signal generation in Chirped Laser Dispersion Spectroscopy (CLaDS). Two optical arrangements based on electro-optical modulators significantly reduce CLaDS system complexity and enable optimum performance when applied to detection of GHz-wide molecular transitions. Proof-of-principle experiments in the near-infrared spectral range are presented and potential strategies for application in the mid-infrared are discussed.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate an optical steganography method with two dimensional encryption to dramatically improve the privacy of optical networks. The transmitted stealth signal carried by noise is secretly hidden under the public channel. OCIS codes: (060.2330) Fiber optics communications; (060.4785) Optical security and encryption.
Conference on Lasers and Electro-Optics (CLEO); 06/2013
[Show abstract][Hide abstract] ABSTRACT: We propose and demonstrate a proof-of-concept for a novel multiplexing scheme for high-performance optical interconnects. Our approach is based on waveguide coupling using multilevel detection to increase the system throughput without increasing aggregate bit rate.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate tunable fast light in a semiconductor optical amplifier based on cross-gain modulation. Up to 60 ps amplitude-invariant time delay is achieved on a 500 MHz microwave signal.