A saturable absorber for the iodine laser

An absorber for iodine laser pulses has been developed using iodine atoms in the ground state as the absorbing species. The iodine atoms have been produced by dissociation of gaseous molecular iodine in a heated cell. The absorption is easily saturated at moderate energy densities.     

Stability investigations of laser with saturable absorber

Stability of steady solutions of semiclassical laser-absorber model is investigated. It is found that the solutions exhibit instabilities for all values of cavity losses and, for some values of parameters, additional instability, connected with phase, appears. It is also shown by a numerical calculation that in an unstable region periodic and erratic motion can exist above criticallity.Supported in part by the Polish Ministery of Science, Technology and Higher Education, Project M.R.I.7     

Excitability in a semiconductor laser with saturable absorber

We show that a monolithic and compact vertical cavity laser with intracavity saturable absorber can emit short excitable pulses. These calibrated optical pulses can be excited as a response to an input perturbation whose amplitude is above a certain threshold. Subnanosecond excitable response is promising for applications to novel all-optical devices for information processing or logical gates.     

Stochastic resonance in a laser with saturable absorber

Summary We have investigated, experimentally and theoretically, the occurrence of stochastic resonance (SR) in a laser with saturable absorber: a non-linear optical system presenting optical bistability and self-pulsed regimes for the laser output intensity. In the optical-bistability regime we have obtained an excellent demonstration of SR by studying Fourier spectra and residence time distributions; operating just below the Hopf bifurcation that originates pulsed periodic regime we have obtained experimental evidence of the SR phenomenon. For operation close to the Hopf bifurcation, the theoretical analysis (performed through numerical simulations) has demonstrated that simultaneous presence of noise and periodic forcing generates excursions far from equilibrium; from the locking between these excursions and periodic forcing the SR phenomenon may arise. Paper presented at the International Workshop “Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing and Related Phenomena”, Elba, 5–10 June 1994.     

Correlation functions for a laser with saturable absorber near threshold

We study in the threshold region the relaxation times and the correlation functions of the field amplitude and of the intensity fluctuations for a solid-state laser containing a saturable absorber in the domain of the parameter space where bistability can occur. We show that the relaxation times display in a small domain above threshold a net-like structure which disappears in the polynomial approximation. The noise spectrum is nearly lorentzian only in a very small domain around the transition point and well above threshold. The line-width displays the well-known sharpening at and above threshold.Supported in part by the Polish Ministry of Science, Technology and Higher Education, Project M.R.I.7Chercheur qualifié F.N.R.S.     

Graphene saturable absorber mirror for ultra-fast-pulse solid-state laser

High-quality graphene sheets with lateral size over 20 μm have been obtained by bath sonicating after subjecting the wormlike graphite marginally to mixed oxidizer. To date, to our knowledge, they are the largest graphene sheets prepared by exfoliation in the liquid phase. A saturable absorber mirror was fabricated based on these sheets. We exploited it to realize mode-locking operation in a diode-pumped Nd:GdVO(4) laser. A pulse duration of 16 ps was produced with an average power of 360 mW and a highest pulse energy of 8.4 nJ for a graphene mode-locked laser.     

Two-dimensional tellurium saturable absorber for ultrafast solid-state laser

Two-dimensional(2 D) Te nanosheets were successfully fabricated through the liquid-phase exfoliation(LPE) method. The nonlinear optical properties of 2 D Te nanosheets were studied by the open-aperture Z-scan technique. Furthermore, the continuous wave mode-locked Nd:YVO_4 laser was successfully realized by using 2 D Te as a saturable absorber(SA) for the first time, to the best of our knowledge. Ultrashort pulses as short as 5.8 ps were obtained at 1064.3 nm with an output power of 851 m W. This primary investigation indicates that the 2 D Te SA is a promising photonic device in the fields of ultrafast solid-state lasers.     

Bifurcation phenomena in a laser with saturable absorber I

We investigate the bifurcation diagram of a laser with saturable absorber in the low and medium intensity regimes. The linear stability of the stationary solutions corresponding to these regimes is studied. In the low intensity domain, a Hopf bifurcation point is determined from which a time-periodic solution emerges. This solution is contructed and its stability is analyzed in the vicinity of the bifurcation point. It is shown that this time-periodic solution is stable in a finite domain of the parameter space.     

含可饱和吸收体的单模驻波激光系统的定态行为

具体给出了含可饱和吸收体的单模驻波激光系统的哈密顿(Hamiltonian)量和序参量运动方程,并对序参量的定态解做了线性稳定性分析。结果表明,驻波系统在阈值附近的定态行为(非平衡相变行为、双稳行为、临界点附近的指数行为等)与行波系统定性类似,但具体细节有异。特别不同于行波的是,驻波情形下三个定态解中的I_分支有可能实现。     

Self-pulsing localized structures in a laser with saturable absorber

We consider a broad area heterostructured semiconductor laser with an integrated saturable absorber in a monolithic configuration. We extend beyond the single-longitudinal mode approximation a model already used to predict transversely localized structures or cavity solitons (CSs) in a shorter device and we numerically demonstrate the existence of self-pulsing transverse localized structures. Like CSs, these structures can simultaneously coexist in different transverse locations.     

Phase transition analogies in a laser with saturable absorber

The possible threshold behaviours of a four-level laser in the presence of an saturable absorber are examined. In the parameter space of the absorber the regions where the threshold behaviours resemble first or second order phase transitions are found. The analysis is based on the semi-classical approximation and makes use of some concepts taken from Thom's theory of catastrophes.     

Cavity soliton laser based on VCSEL with saturable absorber

We study theoretically a broad-area vertical cavity surface emitting laser (VCSEL) with a saturable absorber. We show numerically the presence of cavity solitons in the system: they exist as solitary structures formed through a modulationally unstable homogeneous lasing state that coexists with a background with zero intensity. Such a peculiar scenario endows the solitons with unique properties compared to cavity solitons in most previously studied optical systems. In particular, these solitons do not as such rely on a proper phase of the addressing pulses to be either created or deleted. We show that exciting and deleting the solitons depend crucially on whether a threshold in the soliton peak has been reached.     

High-energy saturable absorber mode-locked fiber laser system

We demonstrate a mode-locked erbium-doped fiber laser with a 1-microm InGaAs saturable absorber that produces 84-ps, 1-nJ transform-limited pulses. Measurements of the InGaAs multiple quantum well revealed a slow saturable absorber that is useful for passive mode locking. Optical fiber was added to extend the cavity and vary the repetition rate from 51 kHz to 5.4 MHz. The narrow spectral width of the laser output (<0.04 nm) permits amplification to 0.2 microJ/pulse with minimal pulse broadening. Pulse energies as large as 1.7 microJ can be achieved with pulse widths of <330 ps. Average powers of 0.5 W at megahertz repetition rates are demonstrated.     

Bifurcation of periodic solutions in a laser with saturable absorber

We investigate a Hopf bifurcation at complex conjugate double eigenvalues in semiclassical equations of a laser with saturable absorber where the degeneracy of eigenvalues is implied by a symmetry. The bifurcation analysis is undertaken within a more general system of nonlinear ordinary differential equations invariant under the same transformations as laser equations. It is proved that three periodic solutions exist and their stability criteria are found.     

Mode-locked Yb-fiber laser with saturable absorber based on carbon nanotubes

An ytterbium-fiber laser with the self-mode-locking using a saturable absorber based on carbon nanotubes is presented. Original films that contain carbon nanotubes make it possible to generate pulses with a duration of 16 ps and a mean power of up to 10 mW at a wavelength of 1058 nm and a repetition rate of 125 MHz     

氧化石墨烯被动调Q掺铒光纤激光器

报道了基于氧化石墨烯的被动调Q掺铒光纤激光器。激光器采用环形腔结构,调Q器件为自制的氧化石墨烯可饱和吸收镜。泵浦功率在81~505 mW范围内时,得到了重复频率68~124 kHz的稳定的调Q脉冲输出,脉宽为0.47~1.60 s。由于泵浦功率限制,激光器最大输出功率为10 mW, 相应单脉冲能量为80.6 nJ。此种基于氧化石墨烯可饱和吸收体的被动调Q光纤激光器体积小、成本低廉、结构简单、稳定性高、光束质量高,具有广阔的应用前景。     

Mode-locked fiber laser with a manganese-doped cadmium selenide saturable absorber

We demonstrate the generation of mode-locked pulses in an erbium-doped fiber laser(EDFL) by using a new manganese-doped cadmium selenide quantum-dots-based saturable absorber. The laser produces a soliton pulse train operating at 1561.1 nm with a repetition rate of 1 MHz, as the pump power is varied from 113 to 250 m W.At the maximum pump power, we obtain the pulse duration of 459 ns with a signal-to-noise ratio of 50 dB.