Injection locking in AlGaAs semiconductor laser

Injection locking of AlGaAs double-heterostructure (DH) lasers was studied with respect to locking bandwidth, required power, and coherence. The relation of the locking bandwidth versus the ratio of locked laser power to injected power was consistent with the classical analysis on injection locking phenomena reported by Adler [2]. The measured maximum locking bandwidth was 5.8 GHz when the locking gain was 18 dB. A maximum gain of 40 dB was observed with a 500 MHz locking bandwidth. The power increase in the injected mode agrees well with theoretical values calculated with the van der Pol equation. The interference pattern was observed between an injecting beam and a locked laser beam. Visibility was the same as that obtained by the interference between forward and backward emitted beams in an identical free-running laser. Spurious mode suppression was observed when a single-frequency optical power is injected into an RF-modulated laser. Single longitudinal mode operation was obtained at a sufficiently high injecting level.     

Injection locking of an index-guided semiconductor laser array

This paper describes an analysis of the effects of an injected laser field on an index-guided semiconductor laser array. We assume an injected field that is resonant with the lowest order array mode and a free-running array that is either operating with a higher order array mode or is not frequency locked. For both cases, a sufficiently intense injected field is found to cause the array to operate predominantly in the lowest order mode. Also, according to our analysis, for certain array configurations, it is more advantageous to have the injected field present during the startup of oscillation than to introduce it after the free-running array has reached steady state. Finally, the injection-locked array is found to contain a tilt in the output beam.     

Injection locking characteristics of an AlGaAs semiconductor laser

Injection locking of an AlGaAs double-heterostructure laser was studied with respect to locking frequency width and locking gain. The relation of the locking bandwidth versus the ratio of locked laser to injected power was consistent with the analysis on injection locking phenomena by Adler. Measured maximum locking bandwidth was 3 GHz, when locking gain was 23 dB. The 40 dB maximum gain was observed with the 500 MHz locking bandwidth. By measuring the beat notes between two temperature-stabilized free running AlGaAs lasers, the linewidth was estimated as 10 MHz.     

Fabry-Perot semiconductor laser injection locking

Injection locking of a semiconductor laser is studied using a Fabry-Perot (FP) model. For low injection powers the FP model gives the same results as the rate equation model. At higher injection powers, the FP laser has an unlimited injection locking bandwidth; however, regions of the bandwidth are dynamically unstable. The influence of the linewidth enhancement factor on injection locking and its stability are also studied using the FP model. Finite values of the linewidth enhancement factor lead to increased locking bandwidth, asymmetry in the locking range and a saddle-node bifurcation in the injection locked solutions, of which only lower carrier density arm has linearly stable solutions.     

Injection locking of a passively mode-locked laser

We present and analyze a model of a passively mode-locked laser, which is subjected to injection of a coherent pulse train. The model, based on soliton perturbation theory, predicts the possibility of coherent injection locking, and gives analytical estimates for the locking ranges. The ability to simultaneously lock the timing and the phase of the output pulses of a mode-locked laser to an injected, coherent pulse train is shown. The interesting limiting case of phase locking the mode-locked laser to a constant amplitude external injection, is addressed with implications for future coherent soliton communication systems     

Injection locking of a KrF laser using a frequency-doubledargon-ion laser pulse

The injection locking of a KrF unstable resonator module has been studied experimentally using a dye-laser-amplified, frequency-doubled seed pulse generated from the 496.5-nm output of an etalon-narrowed argon-ion laser. Partial injection locking was observed starting at input powers of 0.1 W, with greater than 90% injection locking being achieved at input powers of over 1 kW. The output linewidth was experimentally determined to be less than 100 MHz, making possible an ultra-high-brightness KrF laser source     

Chaos and locking in a semiconductor laser due to externalinjection

We have analyzed the behavior of a semiconductor laser subjected to increasing external injection. Numerical simulations show the well-known nonlinear modulation and locking regimes, followed by an intermediate chaotic region that precedes definitive locking to the external source at significantly higher injection levels     

Dynamic behavior and locking of a semiconductor laser subjected toexternal injection

In this paper, we analyze the phenomena arising when a monomode semiconductor laser is subjected to external injection from another laser. The system stability is investigated as a function of detuning and of the relative injected power. Different regimes, spanning from phase locking to chaos and coherence collapse, are described by analytical and numerical methods for weak and moderate injection. Previous theoretical studies are extended by describing the inverse transition from chaos to stability and by deriving the final locking condition. Also, further investigation on the coherence collapse regime has been performed. Besides contributing to the exploration of an interesting fundamental phenomenon, the results of this analysis are useful for different applications, including coherent detection and chaotic cryptography     

半导体激光器的自脉动与被动锁模

利用普适GaAlA3双异质结半导体激光器，观察到被动锁模现象。讨论了半导体激光二极管的自脉动、外腔中的诱导自脉动以及被动锁模间的区别与联系。     

Frequency locking of semiconductor laser using PSK modulated signal

A random PSK modulated signal generated with an optical waveguide phase modulator is used to obtain an error signal and lock the frequency of an AlGaAs semiconductor laser to the /sup 7/Rb D/sub 2/ line. The measured error signal is similar to that obtained with sinusoidal phase modulation under the same conditions. The technique could be applied to longer wavelength lasers and other types of laser that cannot be directly modulated such as fibre lasers.<>     

Observation of mode beating and self-frequency locking in a nearlysingle-mode semiconductor laser

The beat spectra between the adjacent modes of a semiconductor laser having no external cavity are reported. Passive beat-frequency locking is observed at high power without a saturable absorber. This self-induced locking is manifested by the dramatic narrowing (by four orders of magnitude) of the beat spectrum between the dominant and adjacent modes. It is accompanied by the transition from nearly single-mode behavior to a highly structured multifrequency optical spectrum     

Injection locking of an optically pumped FIR laser

Phase locking of optically pumped far-infrared lasers to highly stable synthesized signals is an interesting goal, at least for metrological purposes. In this paper, the possibility of obtaining such a stabilization by injection of the reference signal into the laser is investigated, and from the results obtained, it is inferred that this technique can be efficiently used in the frequency range up to 1 THz.     

Injection locking of an additive-pulse mode-locked fiber laser

Injection locking is utilized to synchronize an additive-pulse mode-locked fiber laser to an external pulsed 76.0-MHz laser source. The spectral and temporal performance of the additive-pulse mode-locked fiber laser and the required conditioning are discussed. A low-jitter temporal synchronization is achieved     

Influence of amplitude-phase coupling on the injection locking bandwidth of a semiconductor laser

The strong amplitude-phase coupling in a semiconductor laser is well known to induce an enhancement linewidth factor (1 + ?2) It is shown that it also produces an enhancement of the injection locking bandwidth proportional to (1 + ?2)1/2. The connection with the usual locking bandwidth derived from Adler's equation is pointed out by considering the carrier dependence of the injected cavity resonance frequency.     

Theory of active mode locking of a semiconductor laser in an external cavity

An analytical treatment is given for the active mode locking of a semiconductor laser in an external resonator. The width of the mode-locked pulses is obtained as a function of the laser and cavity parameters and the amount of frequency detuning. The effects of self-modulation and saturation are included in the treatment. The pulse output is compared with that obtained by a strong modulation of the laser diode with no external cavity.     

The semiconductor laser beyond the locking range of optical injection

The voltage of a current-driven optically injected semiconductor laser has been measured. The experiments not only show the well known phenomenon of injection locking but also reveal unprecedented dispersive-like structures around the relaxation oscillation frequencies. Based on the single-mode rate equations a theoretical explanation of both phenomena is given. The dispersive-like structures are shown to be caused by four wave mixing.<>     

半导体激光器的调频特性

本文讨论了半导体激光器(LD)的直接调频(FM)特性,指出随着偏置电流的增大,FM响应降低,伪强度调制(IM)响应增大,并给出了一种新的描述FM能力的方法.     

Injection locking characteristics of semiconductor lasers in double phase conjugate mirror geometry

Phase locking of two semiconductor lasers is demonstrated by injection of the feedback from a double phase conjugate mirror. The stability or quality of the locking is characterised from fringe visibility measurements. Phase conjugate injection into the central mode exhibits an asymmetric stable locking region which extends to greater detunings and asymmetry with increased feedback. High quality locking is also demonstrated by phase conjugate injection into sidemodes up to nine longitudinal mode spacings from the target mode.<>     

Experimental observation of asymmetric detuning characteristics in semiconductor laser injection locking

The effects of refractive index dependence on the active region carrier density in semiconductor laser injection locking have been examined experimentally. Strong asymmetry has been observed in the relation between locked longitudinal mode intensity and the difference between an original longitudinal mode wavelength and the injecting light wavelength.     

Injection locking and synchronization of periodic and chaotic signals in semiconductor lasers

We experimentally investigate the synchronous response of a semiconductor laser to the injection of a periodic or chaotic oscillating optical signal that is generated by a similar semiconductor laser with optical feedback. We show that there are two different types of synchronous response, appearing in separate regimes of laser frequency detuning and injection strength. They are distinguished by the time lag of the slave-laser response with respect to the injection signal from the output of the master laser. The experimental observations are well described by a numerical model consisting of a set of rate equations. It is revealed that the first type of synchronous response corresponds to the complete synchronization solution of the equations and the second type of response is the result of strong driving. The relevance of these two types of synchronous behavior to a number of recent experiments on chaos synchronization and their implications for data encoding/recovery using chaotic carriers are discussed.