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The fate of excited charge carriers in metal halide perovskite semiconductors is influenced by energetic disorder and defects. Here, photoluminescence (PL) blinking is used to probe metastable nonradiative (NR) centers and the nanoscale energy landscape. Temporal activation of an NR center creates a local region with increased NR recombination. Activation and deactivation of this local PL quenching does not only lead to PL blinking, but also to fluctuations of the PL spectra, if the crystal is inhomogeneous in the sense that the PL emission spectrum is slightly different from one location to another. It resembles the spectral hole‐burning technique; however, here the eliminated excited states are chosen by their spatial localization close to the quencher. In MAPbI3, PL spectral fluctuations at low temperature reveal energetic inhomogeneities on the order of 5 to 10 meV. Quenching of the main PL band is often found to correlate with an increase of the low‐energetic tail of the PL spectra, which is attributed to partially radiative recombination of charges captured by the NR center. The transition energy of the NR center is found to be only ≈80 meV smaller than the bandgap, implying that the underlying defect cannot be a single mid‐bandgap state. [ABSTRACT FROM AUTHOR]

We report the results of experiments on observation of specific features in the spectrum of optically detected magnetic resonance in ensembles of NV centers in diamond at room temperature upon excitation of low-frequency transitions by dual-frequency and amplitude-modulated single frequency microwave radiation. The dependence of parameters of these specific features on intensity of optical radiation and power of microwave radiation is investigated. [ABSTRACT FROM AUTHOR]

Abstract We present a new scheme to report on Goos–Hänchen (GH) shift experienced by the Gaussian light beam interacting with an optical cavity filled with four-level sodium atomic medium in the spectral hole burning region with and without Doppler broadening effect. Theoretical atomic density-matrix formalism is employed to obtain the susceptibility of atomic medium while the stationary-phase-theory is used to compute the GH shift in the reflected and transmitted probe beams subjected to control fields. A steep normal slope of dispersion is observed with a maximum and zero probability of transmission and reflection coefficients, respectively, at the regions of the spectral holes burning. In the normal dispersion spectrum at the region of spectral hole burning, positive and negative GH shift is observed, respectively, in the transmitted and reflected light beams. However, at anomalous dispersive regions negative GH shift in the transmission beam and positive GH shift in the reflection beam is observed. The reflection and transmission coefficients as well as the spatial GH shift are the functions of probe detuning, collective phase of control fields, beam incident angle and inverse Doppler broadening effect in the spectral hole burning region. The position and number of spectral holes also depend on the same spectral parametrs as stated above. The study is expected to be useful for optoelectronic devices and optical-clocking applications. Highlights • We investigate spatial Goos–Hänchen (GH) shift in an atomic cell filled with four-level atomic medium in the spectral hole burning region by density-matrix formalism and stationary-phase-theory. • Reflection and transmission coefficients and the corresponding GH shift depend on collective phase, probe detuning, Doppler broadening and incident angle. • The number and positions of spectral holes also depends upon the collective phase of driving fields, probe detuning and incident angle. • At the region of normal dispersion, positive and negative GH shift is observed, respectively, in the transmitted and reflected probe beams. • The reflection and transmission of the probe beam as well as the GH shift are the functions of inverse Doppler broadening effect in the spectral hole burning region. [ABSTRACT FROM AUTHOR]

Biological tissue is a highly scattering medium that prevents deep imaging of light. For medical applications, optical imaging offers a molecular sensitivity that would be beneficial for diagnosing and monitoring of diseases. Acousto-optical tomography has the molecular sensitivity of optical imaging with the resolution of ultrasound and has the potential for deep tissue imaging. Here, we present a theoretical study of a system that combines acousto-optical tomography and slow light spectral filters created using spectral hole burning methods. Using Monte Carlo simulations, a model to obtain the contrast-to-noise ratio (CNR) deep in biological tissue was developed. The simulations show a CNR > 1 for imaging depths of ~5 cm in a reflection mode setup, as well as, imaging through ~12 cm in transmission mode setups. These results are promising and form the basis for future experimental studies. [ABSTRACT FROM AUTHOR]

High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost fabrication and a greater range of accessible material systems. Here we show that crystal properties, such as nuclear spin lifetime, are strongly affected by mechanical treatment, and that spectral hole burning can serve as a sensitive method to characterize the quality of REI doped powders. We focus on the specific case of thulium doped(Tm:YAG). Different methods for obtaining the powders are compared and the influence of annealing on the spectroscopic quality of powders is investigated on a few examples. We conclude that annealing can reverse some detrimental effects of powder fabrication and, in certain cases, the properties of the bulk material can be reached. Our results may be applicable to other impurities and other crystals, including color centers in nano-structured diamond. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate significant narrowing of laser linewidths by high optical density materials with inhomogeneously broadened absorption. As a laser propagates through the material, the nonlinear spectral hole burning process causes a progressive self-filtering of the laser spectrum, potentially reaching values less than the homogeneous linewidth. The transient spectral hole dynamically adjusts itself to the instantaneous frequency of the laser, passively suppressing laser phase noise and side modes over the entire material absorption bandwidth without the need for electronic or optical feedback to the laser. Wide bandwidth laser phase noise suppression was demonstrated using Er3+ doped Y2SiO5 and LiNbO3 at 1.5μm by employing time-delayed self-heterodyne detection of an external cavity diode laser to study the spectral narrowing effect. Our method is not restricted to any particular wavelength or laser system and is attractive for a range of applications where ultra-low phase noise sources are required. [Copyright &y& Elsevier]

Abstract: Behavior of optical impurity spectra in van der Waals glasses is rationalized with the aid of a two-particle Lennard–Jones model of intermolecular interactions. Simple mathematical manipulations with the 6–12 potential yield inhomogeneous distribution functions (IDFs) of zero phonon lines (ZPLs) at different compressions, and the expressions for wavelength dependent pressure shift coefficients of ZPLs (or holes), local phonon frequencies, and linear and quadratic coupling constants. Experimentally, the ZPL to phonon wing intensity ratios (Huang–Rhys or Debye–Waller factors) are measured for bacteriochlorophyll a in glass-forming triethylamine 5K. Enhancement of coupling strength with increasing transition wavelength is observed, in qualitative agreement with the model. [ABSTRACT FROM AUTHOR]

Abstract: Developing new resonant optical materials for spatial-spectral holography and quantum information applications requires detailed knowledge of the decoherence and population relaxation dynamics for the quantum states involved in the optical transitions, motivating the need for fundamental material studies. We report recent progress in studying these properties in erbium-doped lithium niobate at liquid helium temperatures. The influence of temperature, applied magnetic fields, measurement timescale, and dopant concentration were probed using photon echo spectroscopy and time-resolved spectral hole burning on the 1532nm transition of Er3+:LiNbO3. Effects of spectral diffusion due to interactions between Er3+ ions and between the Er3+ ion and 7Li and 93Nb nuclear spins in the host lattice were observed. In addition, long-lived persistent spectral storage of seconds to minutes was observed due to non-equilibrium population redistribution among superhyperfine states. [Copyright &y& Elsevier]

Abstract: Optical fiber doped with lead salts quantum dots (QDs) of different radii, has previously been proposed as a wide-band amplifier in the optical communication range. The emission and absorption spectra of QDs are size-dependent. Optical fiber amplifier doped with QDs of different sizes is an inhomogeneous gain medium. This inhomogeneity is the principle of operation of wide-band quantum-dot-doped fiber amplifiers (QDFAs). To study the effects of inhomogeneity such as spectral hole burning on the amplifier behavior, a fiber amplifier with an arbitrary size distribution of QDs is taken into consideration. The light propagation equations and rate equations for the inhomogeneous medium are presented. To investigate the gain spectrum, the amplifier bandwidth and the spectral hole burning effect on the amplifier behavior, the system of governing equations for the steady-state regime of operation are solved and numerical results are presented. [Copyright &y& Elsevier]

Optical data recording is one of the most widely used and efficient systems of memory in the non-living world. The application of color centers in this context offers not only systems of high speed in writing and read-out due to a high degree of parallelism in data handling but also a possibility to set up models of neural networks. In this way, systems with a high potential for image processing, pattern recognition and logical operations can be constructed. A limitation to storage density is given by the diffraction limit of optical data recording. It is shown that this limitation can at least in principle be overcome by the principle of spectral hole burning, which results in systems of storage capacities close to the human brain system. [ABSTRACT FROM AUTHOR]

Abstract: The Sm3+-doped alkali strontium borate glass-ceramics were obtained by heating of the as-made glasses in air, where Sm3+ ions were reduced to Sm2+ ions. The XRD, optical absorption spectra and luminescence of Sm3+ and Sm2+ ions were investigated. The excitation spectra of the 7F0 → 5D0 transition were measured in the region of 7F0 → 5D1 transition, where spectral holes were burnt within two of the Stark split 5D1 bands. The Sm2+ ions doped glass ceramics exhibit the persistent spectral hole burning at room temperature. The hole depth, which are burned by the DCM dye laser, are about 40% of the total intensity, respectively. It is concluded that the dominant burning mechanism is a photoionization of electron trapping at a site other than Sm3+ ions because of the absence of an antihole around the burned hole. [Copyright &y& Elsevier]

Nonlinear gain in semiconductor ring lasers has been investigated theoretically based on density-matrix equations, including the effects of carrier density pulsations, carrier heating, spectral hole burning, and carrier diffusion. Expressions for non-linear susceptibilities are derived analytically and compared with previous theoretical results. It is found that carrier diffusion have strong effects on both the amplitude and beat frequency dependency of the nonlinear susceptibilities. Various nonlinear parameters are also calculated based on the expressions obtained, and are consistent with published experimental results by other groups. [ABSTRACT FROM AUTHOR]

Abstract: The possible influence of excitation energy transfer on various spectra observable in hole burning (HB) experiments has been analyzed for pigments with quasi-degenerate absorption bands with uncorrelated site distribution functions. It was shown that ignoring this influence can lead to incorrect interpretation of experimental results. Application of the model is demonstrated for the CP43 core antenna complex of plant Photosystem II, which possesses two quasi-degenerate lowest-energy states [Jankowiak et al., J. Phys. Chem. B 104 (2000) 11805]. According to the model, bands A and B observed in HB experiments do not truly represent the whole absorption bands of the two lowest-energy states in CP43. Assuming that the sample can be represented as a sum of the sub-ensembles of the CP43 complexes where one or another state is the lowest-energy one (and therefore is incapable of downhill energy transfer), bands A and B are the lowest-energy bands of these sub-ensembles. With this restriction, the model allows for fast energy transfer between the two lowest-energy chromophores (states) in CP43. It is shown that the transient and persistent HB spectra of the isolated CP43 complexes are in good agreement with the model. [Copyright &y& Elsevier]

Abstract: The small width of purely electronic zero-phonon lines (ZPL) opens attractive possibilities of their study with the help of Doppler effect (DS—Doppler Spectroscopy). In order to shift the ZPL with 10MHz width to a new position the velocities of the detector relative to the source of the order of tens of meters per second are sufficient. The narrower the line or the spectral hole (its negative image), the more efficient is DS. The DS of the spectral holes shapes and the possibilities of the super-sensitive DS are discussed; the peculiarity of the DS frequency modulation (the perturbations of the internal states of the emitter and absorber are absent) is pointed out. Thus it is interesting to study the interference of the photon “with itself” when the frequency of “its half” is changed by DS. [Copyright &y& Elsevier]

We investigate nonlinear carrier dynamics in a multiquantum-well semiconductor optical amplifier (SOA) in the context of ultrafast all-optical logic. A rate-equation model is presented that accounts for two-photon absorption, free-carrier absorption, self- and cross phase modulation, carrier heating, spectral, spatial hole burning, and self- and cross polarization modulation. The nonlinear refractive index dynamics is investigated theoretically and experimentally. We find nonlinear phase changes larger than π radians, which recovers on a timescale in the order of 1 ps. We also investigate a nonlinear AND gate that consists of an SOA that is placed in an asymmetric Mach-Zehnder interferometer. We show that the gate can be operated using 800-fJ optical pulses with duration of 200 fs while having a contrast ratio larger than 11 dB. [ABSTRACT FROM PUBLISHER]

Techniques of spectral hole burning and single-molecule spectroscopy have been used to study thin films of polycrystalline terrylene-doped biphenyl at temperatures between 1.7 and 2.2 K. A very wide range of probabilities of photoinduced spectral transitions of terrylene molecules are indicated by the strong non-exponentiality of non-photochemical hole burning processes and observation of some extremely stable single-molecule lines. Broad distribution of single-molecule linewidths as well as obvious disagreement between their average value and the corresponding holewidth also demonstrate a large variety of spectral behaviour of terrylene impurity molecules. We attribute these effects to spatial variations of local environment of terrylene molecules in an incommensurate matrix of biphenyl. [Copyright &y& Elsevier]

Observations of a directional asymmetry in the sub-ps THz radiation generated from ultrafast excitation of biased GaAs are presented. This asymmetry is inconsistent with the long standing and widely accepted surface-layer current-surge description of the THz emission process. A model based on propagating carrier excitation fronts during spectral-hole-burning is proposed to explain these observations. This model introduces new roles for the semiconductor optical and carrier transport properties in determining the efficiency of the THz generation process. [Copyright &y& Elsevier]

Accumulated spectral hole burning is demonstrated for self-organized InAs/GaAs quantum dots (QDs) embedded in the space-charge region of a p–i–n diode. In two-color experiments, selective charging of QDs by resonant optical excitation is proved. A hole storage time of 1.5 ms leads to saturation densities of only 0.5 mW/cm−2. The results show the potential of inhomogeneously broadened ensembles of self-organized QDs for parallel optical storage. Additionally, spectral hole burning is used to identify the positive trion and to estimate the trion binding energy. [Copyright &y& Elsevier]

Persistent spectral holes in the inhomogeneously broadened 4f1–4f05d1 zero-phonon transitions in LuPO4:Ce3+ and YPO4:Ce3+ crystals were burned at T=2 K. The holes observed in absorption were deep (up to 50%) and could be observed at least minutes after they were burned. The burning process was very efficient and is due to a single photon process. The observed spectral holes are burned in a photochemical process of photoionization of Ce3+ ions involving electron tunneling from Ce3+ centers to traps. [Copyright &y& Elsevier]

We present a model for quantum-well (QW) semiconductor optical amplifiers (SOAs) that considers bidirectional field propagation and the carrier densities in the barrier and QW regions. Carrier capture from the barriers into the QWs and carrier escape from the QWs to the barriers are included by means of effective capture and escape times. The model incorporates the wavelength dependence of the optical response of the active region and the effects of spectral hole burning via an analytical approximation to the susceptibility of the active material, which allows one to very effectively include the wavelength dependence of the output properties of the SOA. The model is used to analyze the experimental results obtained for a multiquantum-well SOA. The simulations results show a good agreement with the experimental data when a carrier-density dependent escape time from the QW to the barrier regions is considered. [ABSTRACT FROM PUBLISHER]

A new theoretical/numerical model of the spectral hole burning (SHB) effect in erbium-doped fiber amplifiers (EDFAs) is suggested. A new measurement technique for SHB measurement is developed. Experiments are conducted to identify the particular mechanism of SHB. A computer simulation program is developed using this approach. The shape and depth of the spectral hole are in accordance with the suggested theory. [ABSTRACT FROM PUBLISHER]

A few examples of progress of studies and applications of purely electronic zero-phonon line are considered: new experimental values of the narrowest line, femtosecond time-and-space-domain holography and the Taffoli gate by means of it; promises of quantum computing compared to what already done in holography. [Copyright &y& Elsevier]

We report optical studies of the new material – Cr3+-doped lithium–germanate glass, containing Li2Ge7O15 (LGO) nanocrystalline particles. While only broadband 4T2–4A2 fluorescence from the low-field octahedral Cr3+ sites was observed from Cr3+ ions in the glass, in LGO nanocrystals high-field Cr3+ centers emit 2E–4A2 (R–lines) fluorescence. The process of crystallization in the course of isothermal annealing of glasses was monitored spectroscopically and the nucleation of LGO crystallites was observed starting from the smallest clusters. Using the 2E–4A2 fluorescence spectra it is possible to detect the ferroelectric phase transition in LGO:Cr3+ nanocrystals, whose critical temperature was found to be similar to that of the bulk crystals. Long-lived spectral holes were burned in the inhomogeneously broadened R-lines of Cr3+ in LGO nanocrystals at low temperatures. The linear temperature dependence of hole widths shows that the homogeneous broadening of 4A2–2E transitions of Cr3+ in nanocrystals is due to interaction of Cr3+ electronic levels with the two-level systems (TLS) of the surrounding glass. The range of the Cr3+-TLS elastic dipole–dipole interaction is estimated. [Copyright &y& Elsevier]

I offer some reflections on the past three decades of high-resolution spectroscopy of rare-earth ions in solids which was ushered in by the development of tunable lasers in the mid 1970s. A brief review is given of some of the accomplishments in the area of spectral hole-burning and coherent transient spectroscopy, emphasizing work with which the author has been associated. Spectral hole-burning has been characterized by a richness of mechanisms. These include population storage in nuclear-spin and electron-spin Zeeman sub-levels, hyperfine and superhyperfine levels and metastable optical levels with corresponding hole lifetimes from many hours to microseconds. In addition, persistent hole-burning has been seen in disordered materials and in those showing photo-ionization or photo-chemistry following excitation into zero-phonon lines. This has made hole-burning a generally useful technique for the measurement of magnetic and electric dipole moments, hyperfine interactions, spin relaxation and thermally induced line-broadening. Photon-echoes have proven to be the prime source of coherence-time information and coherence times as long as several milliseconds corresponding to optical resonance widths of less than 100 Hz have been reported. Tables summarizing these results and providing references to original work are included. [Copyright &y& Elsevier]

We present some preliminary results on the photophysical properties of a new supramolecular assembly C60–H2TPP, studied at low temperatures by optical spectroscopy. While the absorption spectrum in the long wavelength range reflects the dominant contribution of the porphyrin moiety, the fluorescence spectrum is dominated by the emission coming from the pyrrolidino[60]fullerene moiety. No fluorescence line narrowing effect was observed when exciting within the lowest absorption band assigned to the porphyrin moiety. However, the demonstration that narrow spectral holes can be burnt in this band reveals that the excited state of the porphyrin moiety is not strongly affected by electron–phonon coupling with the host despite its covalent link with a bulky fullerene. [Copyright &y& Elsevier]

In search for efficient near infra-red systems exhibiting broadband significant persistent spectral hole-burning properties for coherent femtosecond pulse-shaping purposes, we have recently demonstrated the potentiality of C70 fullerene to act as an optical enhancer of the hole-burning properties of Si-naphthalocyanine (SiNPc)-doped PVB films in two-colour hole-burning experiments. We hereby report on an increase of the one-colour hole-burning efficiency of SiNPc when C70 is present. We present some spectroscopic evidence that the energy initially absorbed by SiNPc molecules excited at 792 nm is transferred to C70 fullerene molecules, allowing them to play a role as hole-burning activators. [Copyright &y& Elsevier]

We report on the spectroscopic and hole burning properties of free-base naphtophthalocyanine with and without 1-chloranthracene in polymer host. These materials exhibit a strong 0–0 absorption band in the region 800 nm matching the wavelength range of most semiconductor and Ti:Sapphire lasers. The materials studied feature two persistent hole burning photochemical mechanisms, i.e. one-photon proton tautomerization, and two-photon-gated hole burning likely due to donor–acceptor electron transfer. The last mechanism includes the long living intermediate state. The hole width at 1.5 K is about 300–400 MHz depending on the hole burning conditions, while the inhomogeneous width is about 107 MHz. Holographic storage is an important potential application of these materials. We demonstrated 10 plane wave holograms angularly multiplexed at one frequency channel in a spectral hole burning medium. It was shown that the M/# is still a valid system metric and the measured M/# in one frequency channel is about 0.01. [Copyright &y& Elsevier]

The earlier discovery by G.J. Small and his group of the exceptional hole burning properties of aluminum phthalocyanine tetrasulfonate (AlPT) in hyper quenched water encouraged us to look for other suitable hosts in which such properties could be preserved. The non-photochemical hole burning behavior of AlPT in various hosts: dense inorganic or hybrid xerogels, light aerogels and porous Vycor glasses soaked with dye-doped water is investigated. The crucial role played by water or the silanol groups in xerogel pores is underlined by our experiments, the hole burning efficiency becoming quite low in a hybrid xerogel or in a dried porous glass. [Copyright &y& Elsevier]

Broadening and shifts of spectral holes by changing the hydrostatic pressure at 2 K were measured for dimethyl-s-tetrazine probe molecules in durene crystal, both pure and doped with hexachlorobenzene (HCB) at 2 mol%. The HCB molecules act as elastic defects and cause increase in inhomogeneous broadening as well as in the pressure-induced broadening of spectral holes. However, the relative pressure broadening (scaled to the inhomogeneous linewidth) decreases with pressure. The HCB concentration also affects the color effect in pressure broadening, i.e. its dependence on the spectral position. The observations are qualitatively interpreted proceeding from the diaelastic model [J. Chem. Phys. 104 (1996) 5384]. [Copyright &y& Elsevier]

We have, for the first time, experimentally verified the black box model based upon the knowledge in the form of characteristic tilt functions and demonstrated accurate characterization of erbium-doped fiber amplifiers (EDFAs) in wavelength division multiplexing (WDM) system operation [ABSTRACT FROM PUBLISHER]

The spectral hole burning effects and gain dynamics of all-optical gain clamped multichannel erbium-doped fiber amplifiers (EDFAs) are modeled. The two-level laser model is used to write the propagation and rate equations of the inhomogeneous laser medium. The governing equations are an uncountable system of partial differential equations (PDEs). After some mathematical manipulations, averaging over the fiber length and introducing an approximation method, the system of PDEs is converted to a finite system of ordinary differential equations (ODEs). The gain dynamics and hole burning of an all-optical stabilized multiwavelength EDFA and the transient response of an optical fiber inverter are analyzed by the solution of the system of ODEs. Theoretical results are in good agreement with the published experimental result [ABSTRACT FROM PUBLISHER]

A simple dynamic model of laser-gain clamped erbium-doped fiber amplifiers (EDFAs) using ordinary differential equations is presented. The model not only provides a fast means of calculating EDFA gain dynamics, but also shows explicitly how the laser relaxation oscillation frequency and damping constant are affected by design parameters through analytical expressions. It is shown that the dynamic power excursion caused by relaxation oscillations can be reduced by increasing the oscillation frequency. The simplified model has two limitations: first, the amplified spontaneous emission (ASE) spectrum is not fully resolved and the noise figure can not be studied; second, the effect of spectral hole burning, which also causes gain excursion, can not be modeled. The first limitation can be removed by ASE-resolved modeling, where the concept of average inversion is also utilized to save computing time [ABSTRACT FROM PUBLISHER]

• Spectral holes of the laser pulse are created with the spontaneously generated coherene in a medium. • The depth of the spectral holes of the laser pulse gets deeper with increasing of the Kerr field. • Maximum transmission of the probe laser pulse at holes is achieved with SGC and Kerr nonlinearity. We study the control over spectral hole burning in four-level N-type system via spontaneously generated coherence (SGC) and Kerr nonlinearity in an inhomogeneous Doppler broadening medium. We consider a co-propagating probe laser beam and a counter-propagating control laser beam at the same time. Multiple spectral holes are created with the spontaneously generated coherence in the medium. The depth of the spectral holes gets deeper with increasing of the Kerr field. We study the group index and the transmission of probe laser pulse in SHB regions that lead us to achieve maximum transmission and much steeper group index in the system with increasing the strength of the Kerr field. [ABSTRACT FROM AUTHOR]

The dependence of the dynamical response of spectral hole burning (SHB) of an erbium-doped fiber amplifier (EDFA) on temperature is investigated. Experimental results show that gain variations decrease with increasing temperature. The dependence of the transition time on temperature is weak with a trend to larger values at higher temperatures. We also observe that EDFAs using two or three energy levels of the erbium ions show a similar behavior with respect to temperature variation. However, the three-level EDFA presents a higher dependence of the magnitude of induced gain variations on temperature. [ABSTRACT FROM PUBLISHER]

In this work the 1. 53 μ m transition of 167Er 3 + : YVO 4 is investigated with high-resolution laser spectroscopy at sub-Kelvin temperatures. At zero field, hyperfine splitting of approximately 2 GHz is observed, and the optical absorption line is divided into three separate bands. With an external magnetic field of 1 T, the phase memory time has reached the superhyperfine limit, corresponding to an effective homogeneous linewidth which is less than 1 kHz. We have also performed spectral hole burning experiments and the ground-state hyperfine lifetime is longer than 15 s. These properties indicate that 167Er 3 + : YVO 4 is a promising candidate material for potential quantum memory applications working at telecom wavelengths. • Coherent optocal spectroscopy at sub-Kelvin temperatures. • Working at telecom wavelength. • Homogeneous linewidth less than 1 kHz. • Spectral hole lifetime longer than 15 s. [ABSTRACT FROM AUTHOR]

Spectral hole burning is examined via surface plasmon at the interface of Cesium and Gold atomic medium. Kerr nonlinearity effect creates a spectral hole in the absorption spectrum and also enhances dispersion of the surface plasmon polariton. The group speed of surface plasmon polariton is investigated and found to be slowed down. It is also noticed that the group index of surface plasmon polariton is enhanced in the hole burning region in the presence of Kerr effect. This work may have significant applications in data storage devices and plasmonster technology. [ABSTRACT FROM AUTHOR]

We demonstrate the first 10-GHz instantaneous bandwidth radio-frequency spectrum analyzer based on spectral hole burning in Tm3+:YAG. It exhibits 10 000 frequency channels and a resolution better than 1 MHz. Thanks to the fast and linear chirping capabilities of the laser used, it has a potential 100% probability of interception and a response time in the millisecond range. Its linear dynamic range of 16 dB is presently essentially limited by the modest amount of optical power available and can be further improved. [ABSTRACT FROM PUBLISHER]

The gain dynamics of a symmetrical multiple-quantum-well semiconductor optical amplifier (SOA) with wide gain-bandwidth are measured by a two-color heterodyne pump-probe technique. Short optical pulses are generated by using optical filters to select spectral components from compressed supercontinuum optical pulses. To maintain durations of the order of 100 fs over the entire gain bandwidth of the SOA, the pulse broadening caused by frequency shifters is compensated by fibers with lengths optimized for respective wavelengths. We measure the wavelength dependences of the recovery time of carrier heating (CH) and the gain reduction due to CH. The gain reduction caused by spectral hole burning is observed. [ABSTRACT FROM PUBLISHER]

The accuracy of erbium-doped fiber amplifier gain characterization tests has been evaluated using reduced sets of wavelength-division-multiplexing laser sources. Wavelength grids with both uniform and nonuniform wavelength spacing have been evaluated. Experiments show that it is necessary to maintain equal spectral density of source power per region in order to operate at the same saturation/inversion conditions of the amplifier. By doing so, acceptable results were obtained for a laser configuration with 400-800-GHz nonuniform spacing, employing 12 lasers [ABSTRACT FROM PUBLISHER]

This letter verifies experimentally that gain tilt in amplified systems due to Raman crosstalk, when separated from gainshaping effects of the erbium-doped fiber amplifier (EDEA), accumulates as the sum of individual span contributions. This letter also demonstrates that a property of the EDFA, believed to be spectral hole burning, acts to level the gain tilt induced by Raman crosstalk. [ABSTRACT FROM PUBLISHER]

Optical gain control (OGC) can be used to lock the inversion of an erbium-doped fiber amplifier (EDFA), assuming that the gain medium is homogeneous. However, EDF's exhibit certain degrees of spectral hole burning. As a result, when the OGC laser power and the spectral-hole depth at the laser wavelength change, the inversion of the EDFA changes accordingly with a fixed OGC cavity loss. In this work, a saturable absorber is placed in the OGC laser cavity to adjust the cavity loss dynamically and compensate the gain tilt caused by the OGC laser spectral hole burning. It is demonstrated that the steady state gain variation of a surviving channel in an optically gain controlled EDFA is improved from 1.3 dB (with a fixed loss) to 0.4 dB (with a saturable absorber in the cavity). The transient response of this gain control scheme is also discussed [ABSTRACT FROM PUBLISHER]

We report a novel method for automatic gain control of optical amplifiers: dual-cavity optical automatic gain control. The method exploits inhomogeneous broadening in erbium-doped fibers to clamp the erbium gain spectrum with two oscillating lasers. The technique significantly reduces surviving channel steady-state and transient power excursions by automatic reduction of relaxation oscillations and spectral hole burning [ABSTRACT FROM PUBLISHER]