Dual-beam Optical Injection Research Articles

Photonic generation of tunable dual-chirp microwave waveforms using a dual-beam optically injected semiconductor laser.

An approach to generating dual-chirp microwave waveforms (DCMWs) is proposed and experimentally demonstrated. The proposed scheme consists of a typical semiconductor slave laser (SL), which is subject to a dual-beam optical injection from two master lasers with one being positively detuned (${\rm ML}_1$ML1) and the other negatively detuned (${\rm ML}_2$ML2) from the SL. Under proper injection conditions, the SL operates in the so-called Scenario B of dual-beam injection. After optical-to-electrical conversion, a dual-frequency microwave signal can be generated with one of its two frequencies increasing linearly and the other decreasing linearly as the ${\rm ML}_1$ML1 injection strength is increased. By incorporating a fast injection strength controller (formed by an intensity modulator and an electrical control signal), a DCMW with a large time-bandwidth product can be generated. In the experimental demonstration, a DCMW with a temporal period of 1 µs has been obtained. This simultaneously offers an up-chirp (13.4-20.2 GHz) and a down-chirp (27.3-20.5 GHz), and its frequency tunability has been achieved by simply adjusting the injection parameters. Furthermore, the auto-ambiguity function of the generated DCMW has also been investigated, which proves that the proposed scheme has the ability to improve the range-velocity resolution and, thus, could be promising for use in radar systems.

Chaos Bandwidth Enhancement of Fabry–Pérot Laser Diode With Dual-Mode Continuous-Wave Optical Injection

We show numerically that dual-mode continues wave optical injection into a Fabry-Perot laser diode subject to optical feedback generates a chaos bandwidth, which is four to six times that without optical injection. As a comparison, it is shown that single-mode optical injection can increase the chaos bandwidth threefold with careful choice of detuning. Furthermore, any combination of dual-mode injection will enhance the chaos bandwidth and especially for strong injection and over relatively large positive detuning ranges. Even, when the bias current of the Fabry-Perot laser diode is relatively low, the bandwidth of chaos can reach 35 GHz after dual-mode optical injection, which is six times than that of without optical injection. The enhanced bandwidth with dual-beam optical injection is in accordance with our previous experiments [25]. The present simulations provide detailed guidance on the choice of experimentally accessible parameters to generate chaotic signals with enhanced bandwidth by using single or dual-beam optical injection into a Fabry-Perot laser diode with optical feedback.

Experimental investigation on the nonlinear dynamical states of DFB semiconductor lasers subject to dual-beam optical injection

The nonlinear dynamic behaviors of the distributed feedback semiconductor laser (DFB-SLs) subject to dual-beam optical injection are experimentally investigated. The results show that the outputs of a DFB-SL subject to dual-beam optical injection display much rich and more complex nonlinear dynamical behaviors compared with that of a DFB-SL subject to single-beam injection. By fixing the oscillated wavelengths of two injection optical beams and continuously changing injection strengths of two injection optical beams, the output optical spectra and power spectra of the DFB-SL under different injection strengths of dual-beam optical injection have been measured. On the basis of the optical spectra and power spectra, some typical dynamical states have been determined under three cases categorized as scenarios A, B and C. Finally, we give the distribution map of the dynamical states of DFB-SL in the parameter space of two injection strengths, and the regions for scenarios A, B and C have been indicated.

Comparisons of typical nonlinear states in single- and dual-beam optically injected semiconductor lasers

The characteristics of the typical nonlinear states in an optically injected laser system with single- and dual-beam injection are analyzed and compared numerically. Both single- and dual-beam optical injection systems can generate periodic oscillations and chaos states but with different characteristics. By observing the evolution process of periodic oscillations, it is found that dual-beam injection induced periodic oscillations have multiple time series patterns including continuous periodic signals with single peak (CPS) and continuous periodic signals with subharmonic (CPSSH), while for single-beam injection with either of the dual-beam injection parameters generated periodic oscillations, the extremum numbers of the time series equal to the frequency period numbers of the optical spectrum. In addition, the great advantages of bandwidth enhancement effect for chaos oscillations are obtained by using dual-beam injection. Furthermore, extensive numerical simulations reveal that dual-beam injection system undergoes period-doubling routes to chaos, which is identical to that in single-beam injection system. Finally, the characteristics of newly clustered NDFWM dynamics in dual-beam injection system are analyzed.

Dynamics Maps and Scenario Transitions for a Semiconductor Laser Subject to Dual-Beam Optical Injection

Compared with single-beam injection, dual-beam optical injection increases the complexity and enriches the nonlinear dynamics of a semiconductor laser. The nonlinear dynamics of a dual-beam optically injected semiconductor laser system under various operating conditions are numerically studied by comprehensive comparisons of the output spectra of single-beam injection and dual-beam injection. Complete mapping of the different scenarios induced by dual-beam optical injection is shown for various combinations of detuning frequencies and injection strengths of the two injection beams. Complex dual-beam injection dynamics are mapped, and the dynamics in different scenarios are linked through transitional regions. Characteristics of the transition from one scenario to another are traced and analyzed by comparing the resonance frequency of each dual-beam injection optical spectrum with that of the dominant single-beam injection optical spectrum. Two different types of chaos, each following a period-doubling route, are identified in two different scenarios.

Optical generation of tunable millimeter-wave based on dual-beam optical injection Locked 1550 nm vertical-cavity surface-emitting laser

Based on the spin-flip model, the nonlinear dynamics of a 1550 nm vertical-cavity surface-emitting laser (1550 nm-VCSEL) subject to dual-beam optically injection is investigated theoretically. The results show that a slave 1550 nm-VCSEL (S-VCSEL) under the injection of dual-beam output from two master VCSELs (M-VCSELs) can be driven to enter into an injection locking state under suitable injection parameters. In this case, the outputs of both X and Y polarization modes of the S-VCSEL exhibit periodic oscillation whose frequency is equal to the frequency detuning between the two M-VCSELs, and its optical spectrum contains only two main frequency components and possesses a single sideband spectrum structure. As a result, two mutually orthogonal optical millimeter-waves can be obtained based on the periodic oscillation in a VCSEL subject to dual-beam optically injected locking. Through adjusting the frequency detuning between the two M-VCSELs, the frequency of the millimeter-wave can be tuned continuously in a large range, while the power and modulation depth can also be controlled by adjusting the system parameters.

Dual-beam optically injected semiconductor laser for radio-over-fiber downlink transmission with tunable microwave subcarrier frequency

We propose a downlink broadcast transmission scheme of radio-over-fiber (RoF) system based on period-one (P1) dynamic of dual-beam optically injected semiconductor laser with tunable microwave subcarrier frequency. The transmission performance of 2.5Gb/s data in a 60GHz RoF system is demonstrated through numerical simulations. It is found that the proposed transmission scheme can easily generate a single-sideband (SSB) optical modulation by adjusting the injection strength level of two master lasers (ML), which is favorable to reduce the fading effect due to chromatic dispersion. Furthermore, influences of the pulse amplitudes and duty cycles of the downlink data on the transmission properties are investigated. It is observed that the oscillation of the relative power at the base station induced by fiber dispersion does not vary apparently with the modulation parameters. Once the SSB spectrum is generated by dual-beam optical injection, the downlink transmission performance of the proposed RoF system keeps good stability and reliability.

Photonic Generation of Broadly Tunable Microwave Signals Utilizing a Dual-Beam Optically Injected Semiconductor Laser

We propose and study photonic generation of broadly tunable microwave signals utilizing a dual-beam optically injected semiconductor laser. By injecting a slave laser with two detuned master lasers at the stable locking states, microwave signals with frequencies corresponding to the frequency spacing of the master lasers can be generated. Without the need for a microwave reference source, the dual-beam optical injection scheme has the advantages of low cost and less system complexity. Moreover, without the limitations of period-doubling bifurcation and Hopf bifurcation, by utilizing the period-one oscillation state with a single-beam injection scheme, the microwave signals generated with the proposed scheme have a much broader tuning range. In this paper, optical and power spectra of the microwave signals generated with the dual-beam optical injection scheme are compared with those generated with the optical mixing, the single-beam injection, and the unlocked dual-beam injection schemes. Generation of tunable microwave signals up to 120 GHz is demonstrated, which is currently limited by the locking range of the slave laser determined by the frequency difference between the Hopf (higher frequency) and the saddle node (lower frequency) bifurcation curves.