Optically Injected Semiconductor Laser Research Articles

Bandwidth-enhanced LFM waveform generator based on dynamic control of an optically injected semiconductor laser.

A bandwidth-enhanced linear frequency-modulated (LFM) waveform generation scheme is proposed and demonstrated based on dynamic control of an optically injected semiconductor laser (OISL). The OISL operates at the period-one (P1) oscillation state under proper injection conditions. After photodetection, a tunable microwave signal is obtained with its frequency determined by the optical injection strength and the detuning frequency between the master and slave lasers. For a fixed detuning frequency, an LFM waveform can be generated by introducing an electrical control signal S(t) with a quasi-sawtooth profile to dynamically manipulate the injection strength of the OISL. Then, to overcome the bandwidth limitation by the achievable P1 frequency range under a given detuning frequency, both the injection strength and the detuning frequency are dynamically controlled to achieve a synthesized P1 frequency range, thus generating LFM waveforms with enhanced bandwidths. In our demonstration, LFM waveforms with a synthesized bandwidth of 8 GHz (12-20 GHz) and 24.8 GHz (12.6-37.4 GHz) are generated in the experiment and simulation, respectively.

Photonic generation of high-performance microwave frequency combs using an optically injected semiconductor laser with dual-loop optoelectronic feedback

An approach to generating microwave frequency combs (MFCs) with superior performance is proposed and experimentally demonstrated based on an optically injected semiconductor laser (OISL). The OISL operates at the period-one (P1) oscillation state under proper injection conditions. A sinusoidal voltage signal is used to modulate the P1 state for the initial MFC generation, and then two optoelectronic feedback loops are introduced to enhance the performance of the MFC: a short-delay feedback loop is firstly applied to improve comb contrast based on Fourier domain mode locking (FDML), and a long-delay feedback loop is added to reduce the comb linewidth based on the self-injection-locking technique. In the proof-of-concept experiment, a K-band MFC (18-26 GHz) with a line spacing of 8.45 MHz is obtained, where a comb linewidth of approximately 500 Hz and a comb contrast over 45 dB are simultaneously achieved. Additionally, each comb component exhibits superior performance in terms of phase noise, all below -90dBc/Hz at 10 kHz offset, demonstrating an excellent coherence among these combs.

Optically-Injected-Semiconductor-Laser-Based Tunable Dual-Frequency Optoelectronic Oscillator under Subharmonic Microwave Modulation

To obtain low-phase-noise microwave signals with a widely tunable frequency range, an optoelectronic oscillator (OEO) was constructed on the basis of an optically injected semiconductor laser (OISL) for the generation of high-quality microwave signals. Our OEO relied on the effect of wavelength-selective amplification and the period-one (P1) oscillation under optical injection. The signal’s frequency stability, side-mode-suppression ratio (SMSR) and linewidth were optimized by the subharmonic microwave modulation technique in the OEO loop. The experimental results showed that the frequency of the signal obtained by the proposed OEO could be tuned up to 18 GHz. Using the dual-loop OEO structure, the SMSR was increased to 55 dB. Moreover, the phase noise of the obtained microwave signal was lower than −81 dBc/Hz at 1 kHz frequency offset and −119 dBc/Hz at 10 kHz frequency offset. This was achieved by introducing subharmonic microwave modulation in the OEO loop, respectively. Furthermore, via the utilization of a Fabry–Perot laser diode (FP-LD) in the proposed structure, a dual-loop OEO with different dual-frequency configurations (which could be tuned up to 12 and 18 GHz) was obtained.

A New Image Encryption Algorithm Based on Modified Optically Injected Semiconductor Laser Chaotic System

Compared with general chaotic systems, laser chaotic systems have more complex dynamic behaviors and extremely high sensitivity to parameters and initial values. So far, there are few studies on the application of laser chaotic systems to image encryption. Therefore, this paper proposes a new image encryption scheme based on an optical injection semiconductor laser chaotic system. The encryption scheme mainly includes two processes of scrambling and diffusion. The scrambling process converts the pseudo-random sequences generated by the laser chaotic system into chaotic matrixes and scrambling each pixel through a random point scrambling algorithm. In the diffusion process, the chaotic sequences generated by the laser chaotic system are quantized into random numbers and applied to the improved gravitational model algorithm to achieve the effect of pixel diffusion. The experimental results and security analyses indicate that the proposed algorithm has good image encryption performance and can effectively resist various common attacks on image encryption systems.

Generation of NLFM microwave waveforms based on controlled period-one dynamics of semiconductor lasers.

We propose an approach to generating nonlinear frequency-modulated (NLFM) microwave waveforms, which is based on controlled period-one (P1) dynamics of an optically injected semiconductor laser (OISL). When the optical injection is modulated, the OISL, which originally operates at a P1 oscillation state, acts as a microwave voltage-controlled oscillator (VCO). In the proposed system, the microwave frequency output depends closely on the optical injection strength controlled by the modulation voltage input, while the electrical modulation signal required to generate a desired NLFM microwave waveform can be calculated on the basis of the "voltage-to-frequency" transfer function of the established VCO system. Our simulations and experiments demonstrate that both single-chirp and dual-chirp NLFM microwave waveforms can be readily generated with a bandwidth up to 9 GHz. Considering peak-to-sidelobe ratio (PSLR) of the compressed pulses, the NLFM signals generated by the VCO exhibit a practical improvement of ∼13 dB when compared with LFM signals with the same bandwidth, and the tunability of the generated NLFM signals is also experimentally demonstrated.

Photonic Microwave Generation Based on an OISL by Subharmonic Modulation From an OEO

Photonic generation of a low-phase-noise microwave signal based on period-one (P1) dynamics of an optically injected semiconductor laser (OISL) subject to subharmonic modulation from an optoelectronic oscillator (OEO) is firstly proposed and experimentally demonstrated. Under suitable injection parameters, an OISL can be driven into period-one (P1) dynamics, which can be regarded as a photonic microwave with a relatively large linewidth. By further introducing an OEO with a frequency of 1/2 P1 frequency to directly modulate the OISL, a low-phase-noise photonic microwave with P1 frequency can be obtained. For an OISL operating at P1 oscillation with a frequency of 16.96 GHz, after imposing a 1/2 subharmonic modulation of 8.48 GHz on the OISL by an OEO, the photonic microwave linewidth is reduced from 5.23 MHz to less than 1 kHz, and the single sideband (SSB) phase noise of the final photonic microwave is -102.5 dBc/Hz@10 kHz, which is close to the SSB phase noise of the OEO signal (-104.3 dBc/Hz@10 kHz).

Exploiting the Nonlinear Dynamics of Optically Injected Semiconductor Lasers for Optical Sensing

Optically injected semiconductor lasers are known to display a rich variety of dynamic behaviours, including the emission of excitable pulses, and of rare giant pulses (often referred to as optical rogue waves). Here, we use a well-known rate equation model to explore the combined effect of excitability and extreme pulse emission, for the detection of variations in the strength of the injected field. We find parameter regions where the laser always responds to a perturbation by emitting an optical pulse whose amplitude is above a pre-defined detection threshold. We characterize the sensing capability of the laser in terms of the amplitude and the duration of the perturbation.

Suppression of Intensity and Frequency Noise at Low-Sensitivity Operating Points of Period-One Dynamics of Optically Injected Semiconductor Lasers

Period-one (P1) dynamics induced by an optically injected semiconductor laser oscillate at microwave frequencies. The oscillation frequency of a P1 dynamic can be rendered nearly insensitive to small-signal parameter fluctuations and intrinsic laser noise at appropriate operating conditions of the master and slave lasers. In this paper, the noise-canceling properties of the various low-sensitivity (LS) operating points is demonstrated through their dependency on the noise fluctuation frequency and power. The three different types of LS operating points show their effectiveness in suppressing not only P1 intensity and frequency fluctuations caused by narrowband laser perturbations but also intensity and frequency noise caused by broadband intrinsic and extrinsic noise sources.

Generation of Widely Tunable Narrow-Linewidth Photonic Microwave Signals Based on an Optoelectronic Oscillator Using an Optically Injected Semiconductor Laser as the Active Tunable Microwave Photonic Filter

In this work, a novel optoelectronic oscillator (OEO) structure is proposed for generating widely tunable photonic microwave. In this structure, an optical injection semiconductor laser (OISL) functions as an active tunable microwave photonic filter (MPF). Through controlling the injection power and frequency detuning, the OISL is driven into period-one dynamics whose oscillation frequency can be widely tuned from 10.43 to 65.82 GHz. As a result, the OISL can be regarded as a widely tunable active MPF. By introducing an optical feedback loop, the filtered bandwidth of the widely tunable active MPF can be further reduced. Taking the OISL under optical feedback as a widely tunable narrow-bandwidth MPF and a seeding laser source to establish an OEO structure, widely tunable narrow-linewidth photonic microwave can be generated. The experimental results demonstrate that widely tunable photonic microwaves ranging from 10.43 to 39.10 GHz with linewidths below 0.1 MHz and phase variances below 10−2 (rad2) can be achieved.

Tunable and Broadband Microwave Frequency Comb Generation Using Optically Injected Semiconductor Laser Nonlinear Dynamics

Based on an optically injected semiconductor laser (OISL) operating at period-one (P1) nonlinear dynamical state, tunable and ultrabroadband microwave frequency combs (MFCs) are generated experimentally through further current-modulating the OISL. First, by introducing an injection light with an injection power of $P_{\rm{i}}\,= \,12.42$ mW, whose wavelength is identical to the central wavelength of a free-running distributed feedback semiconductor laser, the OISL can be driven into P1 state with a fundamental frequency of $f_{{0}}\,= \,26.44$ GHz. Next, further modulating the OISL with a modulation frequency of $f_{\rm{m}}\,= \,3.3$ GHz and a modulation power of $P_{\rm{m}}$ = 22.0 dBm, an MFC with a bandwidth of 59.4 GHz within a 10 dB amplitude variation is experimentally obtained, and the single sideband phase noise at offset frequency 10 kHz for all comb lines contained within the bandwidth is below −95.0 dBc/Hz. Finally, through varying the modulation frequency, the MFCs with different comb spacing can be obtained, and the influences of relevant operation parameters on the performances of the generated MFCs have been analyzed.

Optical Pulse Generation by an Optoelectronic Oscillator With Optically Injected Semiconductor Laser

A frequency tunable short optical pulse generation scheme based on a self-starting optoelectronic oscillator (OEO) with an optically injected semiconductor laser is proposed and investigated. The generation of optical pulses with a repetition rate coarsely tuned from 6.5 to 15 GHz are demonstrated. Phase noise of the electrical clock signal from the OEO is below −101 dBc/Hz at 10 kHz within the whole tuning range, which leads to a very small timing jitter of the generated optical pulses. Assisted by optical pulse compression technique in the OEO, the full-width-at half-maximum of the generated optical pulses is narrower than 20 ps.

High-purity 60GHz band millimeter-wave generation based on optically injected semiconductor laser under subharmonic microwave modulation.

Based on an optically injected semiconductor laser (OISL) operating at period-one (P1) nonlinear dynamical state, high-purity millimeter-wave generation at 60 GHz band is experimentally demonstrated via 1/4 and 1/9 subharmonic microwave modulation (the order of subharmonic is with respect to the frequency fc of the acquired 60 GHz band millimeter-wave but not the fundamental frequency f0 of P1 oscillation). Optical injection is firstly used to drive a semiconductor laser into P1 state. For the OISL operates at P1 state with a fundamental frequency f0 = 49.43 GHz, by introducing 1/4 subharmonic modulation with a modulation frequency of fm = 15.32 GHz, a 60 GHz band millimeter-wave with central frequency fc = 61.28 GHz ( = 4fm) is experimentally generated, whose linewidth is below 1.6 kHz and SSB phase noise at offset frequency 10 kHz is about -96 dBc/Hz. For fm is varied between 13.58 GHz and 16.49 GHz, fc can be tuned from 54.32 GHz to 65.96 GHz under matched modulation power Pm. Moreover, for the OISL operates at P1 state with f0 = 45.02 GHz, a higher order subharmonic modulation (1/9) is introduced into the OISL for obtaining high-purity 60 GHz band microwave signal. With (fm, Pm) = (7.23 GHz, 13.00 dBm), a microwave signal at 65.07 GHz ( = 9fm) with a linewidth below 1.6 kHz and a SSB phase noise less than -98 dBc/Hz is experimentally generated. Also, the central frequency fc can be tuned in a certain range through adjusting fm and selecting matched Pm.

光注入半导体激光器产生单边带效应的研究

光注入半导体激光器产生单边带效应的研究

Effects of the Gain Saturation Factor on the Nonlinear Dynamics of Optically Injected Semiconductor Lasers

The gain saturation factor describes the proportionality between the real and imaginary parts of the optical susceptibility associated with the circulating optical field in the laser cavity. This factor depends on where the laser operates relative to the gain peak. The effects of the gain saturation factor on the characteristics of the nonlinear phenomena induced by optical injection are studied to find the optimal operating conditions for various application requirements. Such requirements include high microwave frequency, low phase noise, broadband frequency tunability, high modulation bandwidth, optical single-sideband modulation, and stability. Optically injected semiconductor lasers of positive, negative, and zero gain saturation factors are compared through mappings of their nonlinear dynamical characteristics as functions of the detuning frequency and the injection strength. It is found that the instability of an optically injected laser is enhanced by a smaller or more negative gain saturation factor. In both stable locking and periodic oscillations, a laser of a positive gain saturation factor that is smaller than the linewdith enhancement factor is most suitable for optical transmission requirements.

Acquiring narrow linewidth microwave signals based on an optical injection semiconductor laser under subharmonic microwave modulation

The performances of microwave signals generated by an optically injected semiconductor laser operated at the period-one (P1) oscillation under 1/2 subharmonic microwave modulation, are investigated experimentally. The experimental results show that under suitable injection condition, the microwave signal output from an optically injected semiconductor operated at P1 oscillation can reach a frequency of 26.5 GHz limited to the experimental conditions and may have a single sideband optical spectrum structure, but the linewidth of the microwave signal is relatively wide (on the order of MHz). After adopting 1/2 subharmonic locking technique, the linewidth of the obtained microwave signal can be reduced from tens of MHz to tens of kHz. Furthermore, we analyze the influences of the power and frequency of the subharmonic microwave on the phase noise of the generated microwave signals, and further map the subharmonic microwave locking region in the parameter space of the power and frequency of the subharmonic microwave.

Heterodyne Random Bit Generation Using an Optically Injected Semiconductor Laser in Chaos

Heterodyne generation of parallel random bit streams from chaotic emission of an optically injected semiconductor laser is investigated. The continuous-wave optical injection invokes chaotic dynamics in the laser. The broadband chaotic emission is detected through optical heterodyning and electrical heterodyning into different channels. The channels digitize the signals into parallel independent random bit streams. Because of efficient utilization of different portions of the chaos bandwidth, heterodyne detections enable parallel generation of random bit streams, offer high total output bit rates, and require no high-bandwidth analogue-to-digital converters. In the experiment, two optical heterodyne channels and four electrical heterodyne channels are implemented. Each channel is required to digitize only 2.5 GHz of a much broader chaos bandwidth. The sampling rate is 10 GHz with five least significant bits selected from every 8-bit sample. The total output bit rate reaches 100 Gb/s and 200 Gb/s for optical and electrical heterodyning, respectively. The standard test suite of the National Institute of Standards and Technology verifies the randomness of both individual and interleaved output bit streams.

Linewidth Sharpening via Polarization-Rotated Feedback in Optically Injected Semiconductor Laser Oscillators

Combining optical injection and polarization-rotated optical feedback in a semiconductor laser can induce self-referenced periodic output that is widely tunable by simply varying the dc-bias points of the system's master and slave lasers. We observed a feedback-induced reduction of the fundamental period-one oscillation linewidth by more than two orders of magnitude relative to the injection-only case. Performance was found to be negatively affected by the interference between the external injection signal and the residual feedback in the same polarization. The nonlinear dynamics of the optically injected semiconductor laser can be used to minimize sensitivity to fluctuations in the operating points. However, the use of the nonlinear dynamics at high oscillation frequencies is limited by the decreasing strength of the interaction between the circulating intracavity optical field and the carrier density.

Photonic Generation of Wideband Time-Delay-Signature-Eliminated Chaotic Signals Utilizing an Optically Injected Semiconductor Laser

Photonic generation of wideband chaotic signals with time delay signature elimination is investigated experimentally and numerically based on a semiconductor laser (slave laser) with chaotic optical injection from a master laser. The master laser is subject to moderate optical feedback where the feedback strength and external-cavity length are fixed, while the slave laser stands alone. The experimental results show that wideband chaotic signals with successful time delay concealment can be generated in the slave laser by simply adjusting the coupling strength and frequency detuning between the two lasers. Furthermore, the numerical results are in accordance with the experimental observations. Finally, we propose a simple method for simultaneously generating multiple streams of high-quality chaotic signals using multichaotic lasers, where the time delay is effectively concealed in the autocorrelation function and delayed mutual information calculated from the chaotic time series.

Comprehensive experimental analysis of nonlinear dynamics in an optically-injected semiconductor laser

We present the first comprehensive experimental study, to our knowledge, of the routes between nonlinear dynamics induced in a semiconductor laser under external optical injection based on an analysis of time-averaged measurements of the optical and RF spectra and phasors of real-time series of the laser output. The different means of analysis are compared for several types of routes and the benefits of each are discussed in terms of the identification and mapping of the nonlinear dynamics. Finally, the results are presented in a novel audio/video format that describes the evolution of the dynamics with the injection parameters.

Dynamics Scenarios of Dual-Beam Optically Injected Semiconductor Lasers

The nonlinear dynamics of a dual-beam optically injected semiconductor laser are studied. Most of the observed dual-beam injection dynamics can be understood from competitions of single-beam injection dynamics that are associated separately with each injection beam. Three general scenarios are identified and mapped for various combinations of detuning frequencies and injection strengths of the two injection beams. In Scenario A, simultaneous injection of two beams completely suppresses the dynamics due to separate single-beam injection and replaces them with the dynamics resulting from strong nonlinear interactions of the two injection beams. In Scenario B, simultaneous injection of two beams does not suppress the dynamics due to single-beam injection of one of the two beams but modifies such dynamics through nearly degenerate four-wave mixing with the other injection beam associated with the suppressed dynamics. In Scenario C, simultaneous injection of two beams does not suppress the dynamics due to single-beam injection of either of the two beams but allows the two dynamics to coexist and mix nonlinearly.