Based on chaos synchronization between two 1550 nm response vertical-cavity surface-emitting lasers (R-VCSELs), we propose and numerically investigate a bidirectional dual-channel chaotic secure communication system. Under delayed dual-path chaotic signal injections from the injection VCSEL (I-VCSEL) with polarization-preserved optical feedback, a driving VCSEL (D-VCSEL) can generate an optimized chaotic signal, which can drive two R-VCSELs to output polarization-resolved chaotic signals with wide bandwidth about 35 GHz and low TDS below 0.1 in a relatively large parameter range. Moreover, high-quality isochronal chaos synchronization between the corresponding linear polarization components of two R-VCSELs can be achieved. In contrast, the synchronization quality between D-VCSEL and arbitrary one R-VCSEL is inferior. On this basis, through the polarization-division-multiplexing technique in conjunction with the chaos modulation (CM) method, this proposed system can realize security-enhanced bidirectional dual-channel message transmission of 30 Gbps bipolar non-return-to-zero signals over a 140 km fiber link with Q-factors above six. After adopting four-level pulse amplitude modulation, 60 Gbps signals can be successfully transmitted over a 60 km fiber link with Bit-Error-Rates (BERs) below the hard-decision forward error correction (HD-FEC) threshold of 3.8×10-3.
KEYWORDS: Logic, Signal to noise ratio, Vertical cavity surface emitting lasers, Simulations, Quantum optical ring resonators, Microresonators, Signal intensity, Polarization, Optical resonators, Fire
In this paper, we propose an all optical JK flip-flop system consisting of three vertical-cavity surface-emitting lasers with embedded saturable absorber (VCSEL-SAs) is proposed and numerically simulated. Also, the effects of injection intensity, delay and noise on the JK flip-flop are numerically analyzed. The results show that, based on the spiking dynamics of excited VCSEL-SA, the proposed all-optical JK flip-flop model can perform all the fundamental functions of conventional JK flip-flop under suitable bias current, injection intensity and perturbation delay between two trigger signals. Moreover, the noise has a little effect on the performance of JK flip-flop, but the proposed system has good robustness to the noise. The results provide a feasibility for the application of VCSEL-SA devices in the future ultrafast neuromorphic computing systems.
Based on two Response Vertical-Cavity Surface-Emitting Lasers (R-VCSELs) subject to identical chaos optical injection with phase modulation and dispersion compensation, we propose and numerically investigate a high-speed bidirectional chaotic secure communication system. The driving VCSEL (D-VCSEL) is used to generate the injected chaotic signals to two R-VCSELs. After introducing the phase modulation and dispersion compensation into injection path, the bandwidth of chaotic carrier from the linear polarization components of R-VCSEL1 and R-VCSEL2 can be extended to 45GHz, and corresponding Time Delay Signatures (TDSs) can be suppressed to about 0.15. Moreover, high-quality chaos synchronization between corresponding polarization components of two R-VCSELs but very low correlation between the D-VCSEL and any R-VCSEL can be achieved. On this basis, the bidirectional dual-channel information transmission of 30 Gbit/s over 100 km fiber link is successfully realized.
We propose and demonstrate a scheme for improving ranging performance of Frequency-Modulated Continuous-Wave (FMCW) radar, in which the transmitting signal is generated by a Semiconductor Laser (SL) under intensity-modulated optical injection. Previous investigations have demonstrated that, through introducing optical injection, SLs can be driven into period-one (P1) oscillation under suitable injection parameters, and the oscillation frequency depends on the injection strength. As a result, through modulating the intensity of injection light, FMCW can be obtained. In this work, we adopt a triangular Frequency-Modulated (FM) signal with a frequency of 11.579 MHz (period of 86.362 ns) to modulate the injection strength, an original FWCM signal with bandwidth of 2.59 GHz (from 13.59 GHz to 16.18 GHz) is generated. Taking such a signal as the transmitting signal of radar, the relative error is within the range of (17.74 % to 26.36 %) for ranging the targets within 2.600 m. The large relative error is due to poor repeatability of the transmitting signal, which can be characterized by the frequency comb contrast of FMCW signal. In order to generate the promoted FMCW signal with higher repeatability, optical feedback with delayed time of 86.362 ns is further introduced into the SL under intensity-modulated optical injection. Under optimized feedback strength, the comb contrast of promoted FMCW signal can arrive at 32.35 dB. Taking the promoted FMCW signal as the transmitting signal of radar, the relative error for ranging the targets within 2.600 m is decreased into the range of (0.42 % to 4.61 %).
In this work, a filter-free scheme of photonic generation of a high-quality 32-tupling millimeter-wave signal based on four dual-port MZMs (DP-MZMs) is proposed and simulated. In this scheme, four DP-MZMs are recombined into the two parallel DP-MZMs and the two cascaded DP-MZMs, respectively. After being modulated by a local oscillation signal, the light from the two parallel DP-MZMs is converted by a photodetector into an electrical signal, which is imposed on the electrodes of the two cascaded DP-MZMs. The simulation results show that the performances of the photonic microwave signal are affected by the modulation index, extinction ratio, and bias voltage of the DP-MZMs. Under the optimized operation parameters, a high-quality 32-tupling millimeter-wave signal with 46 dB radio frequency sideband suppression ratio (RFSSR) and 40 dB optical sideband suppression ratio (OSSR) is generated without using the filter. Because the two cascaded DP-MZMs are modulated by a small signal and there is no filter in the system, the high stability and high utilization rate of the sideband can also be realized in this scheme.
Based on a vertical-cavity surface-emitting laser with saturated absorber (VCSEL-SA) subject to optical injection, we proposed an ultrafast pattern recognition scheme of four-bit binary data and theoretically investigated the recognition performances. The results show that, patterns recognition of different four-bit binary data at Gb/s rate can be realized by adjusting the injection weight of each bit number and optimal weight values can be determined. Although noise has some influences on the patterns recognition speed and accuracy, this proposed system has a certain robustness to noise on the whole. These results provide a promising application prospect for VCSEL-SA based ultrafast photonic neuromorphic system in pattern recognition field.
KEYWORDS: Microwave radiation, Microwave photonics, Photonic microstructures, Semiconductor lasers, Modulation, Microsoft Foundation Class Library, Signal generators, Frequency combs, Phase shift keying, Nonlinear dynamics
Semiconductor lasers (SLs) under external disturbances can be driven into diverse nonlinear dynamical states such as period-one, period-two, multi-period, and chaos. Based on the period-one nonlinear dynamical state in an optically injected semiconductor laser, tunable single-tone microwave signal, ultra-broadband microwave frequency combs, and frequency-modulated continuous wave can be generated. Moreover, through introducing optical feedback, a SL under pulsed current modulation can output pulsed chaotic signal, which can be applied in anti-interference radar.
We proposed a reconfigurable all-optical logic gate (AND, OR) based on a vertical-cavity surface-emitting laser with saturated absorber (VCSEL-SA) subject to dual pulse injection and numerically investigated the effects of injection delay, injection strength and bias current on the system performance. The results show that, through adjusting bias current, the pulse injection strength and the injection delay between two pulses, the reconfigurable all-optical logic gate (AND, OR) can be realized. For a suitable injection intensity, all-optical logic AND and OR gates can be implemented within a certain bias current range. Moreover, both AND and OR gates have good robust to noise under suitable injection strength. These results are expected to open a new window for future ultra-fast neuromorphic computing systems to solve complex classification and decision-making tasks
In this paper, we propose and numerically demonstrate a security-enhanced high-speed chaotic communication system by introducing phase modulation and phase-to-intensity conversion. The driving laser (DL) with delayed optical feedback can be used to generate the chaotic driving signal, which is simultaneously injected into two response lasers (RLs) through a phase modulator (PM) and a dispersion component (De). The simulated results show that, due to the phase modulation and phase-tointensity conversion, TDS of injected chaos signal from DL can be effectively suppressed and its bandwidth can be increased to 39.6 GHz under suitable parameter conditions. Simultaneously injecting the chaos signal into two identical RLs, high-quality chaos signals with weakened TDS and enhanced bandwidth between two RLs can be achieved even under certain parameter mismatches, but the synchronization quality between DL and any one of RLs is extremely bad. Based on the system synchronization, secure transmission of 20 Gbit/s messages can be realized and the transmission distance can be over 200km.
Based on a master-slave frame, we propose and numerically simulate a scheme for generating frequency-modulated continuous-wave (FMCW) signals with broad bandwidth. In such a master-slave system, a semiconductor laser under current modulation with single-tone electrical signal is taken as the master laser (ML), and its output optical signal with modulated power is injected into another semiconductor laser (taken as the slave laser, SL) for generating FMCW. The simulated results show that, under suitable operating condition, the bandwidth and the sweep rate of generated FMCW signal can reach 15.4 GHz and 4.83 GHz/ns, respectively. Through further introducing optoelectronic feedback into SL for suppressing the phase noise, the contrast of the frequency comb in the FMCW signal can be increased by 20.22 dB.
Photonic generation of frequency-modulated continuous wave (FMCW) based on period-one (P1) oscillation of an optically injected semiconductor laser (OISL) is numerically investigated. A modulated optical injection can drive an OISL into P1 oscillation for generating an FMCW signal, and an optical feedback is further introduced to reduce the phase noise of the generated signal. The influences of operation parameters on the performance of the generated FMCW signal are discussed. The numerical results show that under proper operating conditions, a photonic FMCW signal with a sweep range of 12.41 GHz can be obtained. After adopting optical feedback, the frequency comb contrast can be increased to a level more than 30 dB.
A scheme for generating frequency-modulated continuous-wave (FMCW) based on an optically injected semiconductor laser (SL) is proposed and demonstrated experimentally. A modulated light injection drives an SL into period-one (P1) state with modulated microwave frequency for generating FMCW, and then an optical feedback is introduced to further enhance the frequency comb contrast of the generated FMCW. Under proper operation conditions, a FMCW signal with a sweep range of 11.39 GHz (10.08 GHz-21.47 GHz) and a sweep rate of 0.72 GHz/ns is obtained, and the frequency comb contrast is increased by 20 dB after introducing the suitable optical feedback.
A bandwidth-enhanced chaos synchronization communication system is proposed and its communication performance is investigated numerically. The results show that, using a bandwidth-enhanced chaotic signal from a driving vertical cavity surface-emitting laser (D-VCSEL) to drive two mutually coupled VCSELs (MC-VCSELs), the high-quality isochronal chaos synchronization with over 30GHz bandwidth between two corresponding LP modes in the two MCVCSELs can be obtained. Taking two LP modes as two different communication channels and adopting chaos masking (CMS) encryption scheme, this system can realize the bidirectional dual-channel high-speed chaos communication at 10Gbits/s transmission rate. Moreover, the parameters mismatches tolerance of this communication system and the influence of message transmission rate on the communication performance also are discussed.
Based on the period-one nonlinear dynamical state of an optically injected semiconductor laser, an all-optical method for photonic microwave generation is proposed and investigated experimentally. Experimental results show that through jointly adjusting injected optical strength and frequency detuning between the injected light and the solitary laser, a photonic microwave signal with a tunable frequency range of several tens GHz can be acquired. Via by introducing an optical feedback and properly selecting the feedback strength, the linewidth of photonic microwave can be narrowed about two orders of magnitude.
In this paper, a new style state-bistability has been experimentally observed by back and forth sweeping the current of a
semiconductor laser nearby its threshold. Moreover, the influence of the injection power on the width of state-bistability
loop has been analyzed and discussed in detail.
In this paper, the total output power features and the mode power characteristics of the extremely short external cavity
semiconductor lasers (ESECSLs) have been investigated experimentally and theoretically, and a new type of variation of
ESECSL's mode power is reported. The results show that with the variation of the external cavity length at the order of
lasing wavelength, the total output power and the mode power of ESECSLs will hop periodically, and the different mode
presents diverse power characteristics. Especially, some modes, locating at the material gain center of ESECSL, present
unique double peak characteristics. Moreover, the primarily theoretical simulations and the physics explanation about
these double peak characteristics have been given. The theoretical simulation results agree well with the experimental
results. These new type characteristics of ESECSL's mode power may be useful in improving the sensitivity of all-optical
sensors and developing the new type of optical data read-write head.
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