Spectral Hole Burning Effects Research Articles

In vivo ultrasound modulated optical tomography with a persistent spectral hole burning filter.

We present in vivo ultrasound modulated optical tomography (UOT) results on mice, using the persistent spectral hole burning (PSHB) effect in a Tm3+:YAG crystal. Indocyanine green (ICG) solution was injected as an optical absorber and was clearly identified on the PSHB-UOT images, both in the muscle (following an intramuscular injection) and in the liver (following an intravenous injection). This demonstration also validates an experimental setup with an improved level of performance combined with an increased technological maturity compared to previous demonstrations.

Laser guide star return-flux gain from frequency chirping

ABSTRACT Spectral hole burning reduces sodium laser guide star efficiency. Due to photon recoil, atoms that are initially resonant with the single-frequency laser get Doppler shifted out of resonance, which reduces the return flux. Frequency-chirped (also known as frequency-swept) continuous-wave lasers have the potential to mitigate the effect of spectral hole burning and even increase the laser guide star efficiency beyond the theoretical limit of a single-frequency laser. We investigate the return flux of frequency-chirped laser guide stars and its dependence on environmental and chirping parameters. On-sky measurements of a frequency-chirped, single-frequency laser guide star are performed at the Roque de los Muchachos Observatory on La Palma. A fast photon-counting receiver system is employed to resolve the return-flux response during laser frequency sweeps gaining insights into the population dynamics of the sodium layer. At a launched laser power of 16.5 W, we find a maximum gain in return flux of 22 per cent compared to a fixed-frequency laser at a chirping amplitude of the order of 150 MHz and a chirping rate of 0.8 MHz µs−1. Time-resolved measurements during the chirping period confirm our understanding of the population dynamics in the sodium layer. These are the first measurements of return-flux enhancement for laser guide stars excited by a single-frequency-chirped continuous-wave laser. For higher laser powers, the effectiveness of chirping is expected to increase, which could be highly beneficial for telescopes equipped with high-power laser guide star adaptive optics systems.

基于光谱烧孔效应的激光稳频技术研究与进展

基于光谱烧孔效应的激光稳频技术研究与进展

Spatially Resolved Brillouin Spectral Hole Burning in PMF and SMF

We observe the spectral hole burning effect in a polarization maintain fiber (PMF) and a single-mode fiber (SMF) through the interaction between a continuous wave (CW) beam and a high power pulse with two frequency components located around the Stokes and anti-Stokes frequencies of the CW beam. The linewidth of the spectral burning hole is much narrower than that of the intrinsic Brillouin gain spectrum. We experimentally study the position dependent dip formation process in a PMF and an SMF, and explore the possibility of using this narrowed spectral width for distributed temperature and strain sensing with a higher accuracy. A hole burning peak with a linewidth of 9 MHz in a Brillouin gain spectrum with a full-width at half-maximum (FWHM) of 50 MHz is observed in a PMF. Since the frequency measurement accuracy of Brillouin sensor is inversely proportional to the FWHM of detected spectrum, the spectrum hole burning represents a potential for improving the Brillouin peak detection accuracy of distributed Brillouin sensor.

Traveling Wave Model for Frequency Comb Generation in Single-Section Quantum Well Diode Lasers

We present a traveling wave model for a semiconductor diode laser based on quantum wells. The gain model is carefully derived from first principles and implemented with as few phenomeno- logical constants as possible. The transverse energies of the quantum well confined electrons are discretized to automatically capture the effects of spectral and spatial hole burning, gain asym- metry, and the linewidth enhancement factor. We apply this model to semiconductor optical amplifiers and single-section phase-locked lasers. We are able to reproduce the experimental re- sults. The calculated frequency modulated comb shows potential to be a compact, chip-scale comb source without additional external components.

Super-luminescence and spectral hole burning effect in ultra-short length Er/Yb-doped phosphate fiber

We demonstrate super-broad luminescence over 70 nm of bandwidth and spectral hole-burning effect obtained in just a few cm of novel air-clad, highly concentrated Er/Yb-doped phosphate fiber. The fiber is drawn from preforms of glasses within the P2O5 – SrO – Na2O composition. The fabrication process, thermal, structural, and optical properties of the fiber are described.

Robustness and mode selectivity in parity-time (PT) symmetric lasers

We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain values, (3) PT symmetric photonic molecule lasers are more robust than their counterpart structures made of single microresonators; and (4) Extending the concept of single longitudinal mode operation based on PT symmetry in millimeter long edge emitting lasers having smaller FSR can be challenging due to instabilities induced by nonlinear modal interactions. Finally we also present a possible strategy based on loss engineering to achieve more control over the mode selectivity by suppressing the mode that has the highest gain (i.e. lies under the peak of the gain spectrum curve) and switch the lasing action to another mode.

Experimental Investigation of Gain Offset Behavior of Feedforward-Controlled WDM AGC EDFA Under Various Dynamic Wavelength Allocations

Realizing dynamics in the optical layer is becoming more important for efficient optical communication networks such as protection switching in the optical domain or reconfiguring the optical layer to meet traffic fluctuations. This paper experimentally investigates gain offset changes under dynamic optical switching using feedforward-controlled wavelength-division-multiplexing (WDM) automatic gain control erbium-doped fiber amplifiers (EDFAs). Realistic optical switching scenarios are emulated by resolving dynamic routing and wavelength assignment problems. The experimental results demonstrate that channel intensity changes with optical switching and that the intensity changes accumulate as the number of cascaded EDFAs increases. Considering a gain model in wavelength assignment can successfully reduce the channel intensity changes by up to 0.7 dB after five cascaded EDFAs. Effects of gain spectral hole burning on the intensity changes are also discussed.

Wavelength-switchable fiber laser based on few-mode fiber filter with core-offset structure

We propose a wavelength-switchable erbium-doped fiber ring laser based on the few-mode fiber filter with core-offset structure. The filter is constructed by splicing a section of few-mode fiber with two segments of single mode fiber. Meanwhile, the excited modes are effectively selected by controlling the core-offset splicing carefully. The novel filter is based on the interference between fundamental mode and LP11 mode. The single-, dual-, triple- and quad-wavelength fiber laser is accomplished by adjusting the states of polarization controller at room temperature. The principle of operation is mainly based on the saturated spectral hole-burning effect and the balance between the gain and loss in the cavity.

Switchable dual-wavelength erbium-doped fiber ring laser with tunable wavelength spacing based on a compact fiber filter

Abstract In this paper, using a compact fiber filter (CFF), we demonstrate a dual-wavelength erbium-doped fiber ring laser with tunable wavelength spacing. The two oscillation wavelengths are specified by a fiber modal interferometer (MI) and a fiber Bragg grating (FBG) embedded in the MI, which consists of the CFF. Due to the deeply saturated spectral hole-burning (SHB) effect in the erbium-doped fiber, stable dual-wavelength operation is achieved at room temperature and the wavelength spacing can be tuned from 9.29 nm to 11.11 nm continuously when the strain applied to the CFF is changed. By adjustment of the attenuator in the cavity, the laser can operate in dual-wavelength or in wavelength switching modes.

Modeling of Wide-Band Optical Signal Amplification in an EDFA Network Using Tunable Tap

Optical amplification in C and L band region with wave division multiplexing can provide over 160 channels. The paper provides simulation studies of such a wideband erbium doped fiber amplifier which utilizes a tunable tap at the TLS source end. This isolates and provides two parallel channels for simultaneous amplification in both C and L band. Such a configuration has shown to provide a gain well over 20dB from 1525-1615nm bandwidth with average noise figure of 10dB (approx.). Gain saturation effects beyond -20dBm/channel signal level and, gain spectra at different pump powers and amplifier lengths have also been studied. Full Text: PDF References Robert E. Tench, Proc. IEEE Elecronic Componenets and Technology Conference. 9, (1999). J. F. Massicott, R. Wyatt, and B. J. Ainslie, "Low noise operation of Er 3+ doped silica fibre amplifier around 1.6 ?m", Electron. Lett. 28, 1924 (1992). CrossRef Y. Sun, A. Srivastava, J.Zhou, and J. Sulhoff, "Optical fiber amplifiers for WDM optical networks", Bell Labs Technical Journal. 4, (1999) CrossRef H. Ono, M. Yamada and Y. Ohishi, "Gain-flattened Er/sup 3+/-doped fiber amplifier for a WDM signal in the 1.57-1.60-?m wavelength region", IEEE Photon. Technol. Lett. 9, (1997). CrossRef C. Jiang, W. Hu, Q. Zeng and S. Xiao, "High detectivity GaInAs-InP quantum-well infrared photodetectors grown on Si substrates", IEEE Photon. Technol. Lett. 14, 290 (2002). CrossRef M. A. Mahdi, F. R. M. Adikan, P. Poopalan, S. Selvakennedy, W. Y. Chan, and H. Ahmad, "Long-wavelength EDFA gain enhancement through 1550 nm band signal injection", Opt. Commnun.175, 296 (2000). CrossRef H. Chen, M. Leblanc and G.W. Schinn, "Gain enhanced L-band optical fiber amplifiers and tunable fiber lasers with erbium-doped fibers", Opt. Comm. 216, 119 (2003). CrossRef M. A. Mahdi and H. Ahmad, "Gain enhanced L-band Er/sup 3+/-doped fiber amplifier utilizing unwanted backward ASE", IEEE Photon. Technol. Lett. 13, 1067 (2001). CrossRef S. W. Harun, N. Tamchek, P. Poopalan and H. Ahmad, "Gain clamping in two-stage L-band EDFA using a broadband FBG", IEEE Photon. Technol. Lett. 16, 422 (2004). CrossRef T. Sakamoto. "Wide wavelength band (1535?1560 nm and 1574?1600 nm), 28 × 10 Gbit/s WDM transmission over 320 km dispersion-shifted fibre", Electron. Lett.34, 392 (1998). CrossRef Y. Sun et al., "80 nm ultra-wideband erbium-doped silica fibre amplifier", Electron. Lett. 33,1965 (1997). CrossRef T. Kasamatsu, Y. Tano and T. Ono, 13, 31 (2001). S. K. Liaw and Y. K. Chen, "Self-phase modulation coefficient of multiple-quantum-well optical amplifiers", IEEE Photon. Tech. Lett. 8, 876 (1996). CrossRef A. Srivastava and Y. Sun, Optical Fiber Telecommunications, I. P. Kaminov and T. Li, Eds. (San Diego, CA: Academic 2002, vol. VI A). R. Anthony and S.N. Biswas, "Temperature Dependent Gain Analysis of a Cascaded C-Band EDFA DWDM Network", Elseviers Procedia Technol. 4, 92 (2012). CrossRef G. Luo, J. L. Zyskind, I. A. Nagel, and M. A. Ali, "Experimental and theoretical analysis of relaxation-oscillations and spectral hole burning effects in all-optical gain-clamped EDFA's for WDM networks", IEEE J. Lightwave Technol. 16, 527 (1998). CrossRef I.K. Bu Sohn and J.W. Song, "Gain flattened and improved double-pass two-stage EDFA using microbending long-period fiber gratings", Optical Communications. 236, 141 (2004). CrossRef R. Singh, Sunanda and E.K. Sharma, "Gain flattening by long period gratings in erbium doped fibers", Optical Communications. 240, 123 (2004). CrossRef

Electronic spectroscopy, stimulated emission, and persistent spectral hole burning of cryogenic nitrogen matrices doped with tetrabenzoporphin

This paper deals with our on-going work on the electronic spectroscopy of tetrapyrrole molecules embedded in cryogenic hosts. Under nanosecond laser excitation of free-base tetrabenzoporphin molecules in a nitrogen matrix at 8 K, increasing laser pulse energy results in essential enhancement of the intensity of one or several vibronic emission lines in the fine-structure fluorescence spectrum. Some characteristics of stimulated radiation are realized in the observed intense monochromatic radiation as a result of a transition from the purely electronic S1 level to a vibrational sublevel of the S0 state, corresponding to the excitation of C–C stretching vibrations of tetrapyrrole methane bridges. We also report on persistent spectral hole-burning effects. Hole and antihole formation analysis gives some insight on the photochemical properties of tetrabenzoporphin in a nitrogen matrix.

Switchable multi-wavelength fiber ring laser using a side-leakage photonic crystal fiber based filter

A switchable multi-wavelength fiber ring laser is proposed and experimentally demonstrated with a novel side-leakage photonic crystal fiber (SLPCF) based filter incorporated into the ring cavity at room temperature. Stable multi-wavelength laser operations can be achieved due to the spatial mode beating, polarization hole burning and spectral hole burning effects. By adjusting the polarization controller appropriately, the laser can be switched among the single-, dual- and triple-wavelength lasing oscillations whose signal-to-noise ratio is up to 50 dB. In addition, the lasing wavelength can be also tuned and switched by applying the strain to the filter.

增益平坦掺铒光纤放大器中均匀信号强度造成的光谱烧孔效应

Spectral hole burning (SHB) effects in a gain-flattened erbium-doped fiber amplifier (EDFA) are demonstrated to be significant in the presence of large signal power around the 1530?1532-nm wavelength range. These are the first effects reported in a setup employing equivalent power level distribution of 40 channels ranging from 1530 to 1561 nm. To explain this, the introduction of a new local population variable into the laser equation is required to support the original inversion ratio that is determined by the pump lasers. In the analysis section, spectroscopic parameters and high signal powers are considered to be other contributing parameters to the change in the gain characteristics. An improvement to this theoretical basis is suggested by implementing mathematical modeling to validate similarities between the gain shape of simulation to that obtained in the experiment.

Spectral hole burning effects initiated by uniform signal intensities in a gain-flattened EDFA

Spectral hole burning effects initiated by uniform signal intensities in a gain-flattened EDFA

Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

The switchable dual-wavelength erbium-doped fiber laser (EDFL) with a two-mode photonic crystal fiber (PCF) loop mirror and a chirped fiber Bragg grating (CFBG) at room temperature is proposed and experimentally demonstrated. The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror, with the air-holes of the PCF intentionally collapsing at the splices. By adjusting the state of the polarization controller (PC) appropriately, the laser can be switched between the stable single- and dual-wavelength operations by means of the polarization hole burning (PHB) and spectral hole burning (SHB) effects.

Switchable quadruple-wavelength erbium-doped fiber ring laser based on two-segment Lyot–Sagnac filter

We propose and demonstrate a novel switchable quadruple-wavelength erbium-doped fiber ring laser (EDFL) based on two-segment Lyot–Sagnac filter which is used as the wavelength-selective filter. Due to the deeply saturated spectral hole-burning (SHB) effect in an ordinary erbium-doped fiber, the laser realizes stable single-wavelength, dual-wavelength, triple-wavelength, and quadruple-wavelength output by controlling two polarization controllers (PCs) appropriately. The optical signal-to-noise ratio (OSNR) is over 30 dB. The peak fluctuation is less than ~2 dB over 1.5 h at room temperature.

An inhomogeneous theoretical model for analysis of PbSe quantum-dot-doped fiber amplifier

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.

Wavelength dependent ultrafast gain and phase dynamics in bulk SOAs over wide gain region

Based on the semiclassical density-matrix equations, ultrafast probe gain and phase dynamics in bulk semiconductor optical amplifiers excited by a 200 fs Gaussian pump pulse centered at 1,558 nm are numerically investigated and compared over a wide material gain region (1,460–1,650 nm). It is predicted that the recovery time of phase may be longer or shorter than that of gain depending on probe wavelengths. Besides, as functions of probe wavelength, the dynamic gain range and the dynamic phase range have different shapes. Moreover, the wavelength dependence of phase recovery overshoot is illustrated. At last, the probe chirp dynamics and the wavelength dependence of the chirp characteristics are described. These interesting features result from a restriction of the Kramers–Kronig relations and different ways of the competition or cooperation among the effects of spectral-hole burning, carrier heating and two-photon absorption on subpicosecond timescale over the whole concerned band.

Occupation-Dependent Access to Metabolic Energy in Fröhlich Systems

Fröhlich systems model ensembles of electromagnetic-radiation-emitting molecular oscillators residing inside biological cells. The core piece of this theory are rate equations for the quantum-mechanical occupation numbers of the collective oscillation modes that take into account the flow of metabolic energy through the ensemble. In continuation of prior study of feedback patterns implicit in this model, oriented multigraphs representation is used to investigate the case when the pumping source—in analogy with the effect of spectral hole burning in injection lasers—exhibits depletion phenomena dependent on occupation numbers and the eigenfrequencies of the modes. As a result, in comparison with the case when all modes have equal access to pumping source, the onset of energy condensation in the fundamental mode is shifted to higher pumping levels and new feedback loops appear in the representative diagram. The modified theory provides a more realistic description of electromagnetic emission in biological cells.