Line profile distortions in laser-induced impedance change signals for wavelength determination of tunable dye lasers

Microlensing-induced distortions of broad emission line profiles observed in the spectra of gravitationally lensed quasars can be used to probe the size, geometry, and kinematics of the broad-line region (BLR). To this end, single-epoch Mg II or Hα line profile distortions observed in five gravitationally lensed quasars, J1131-1231, J1226-0006, J1355-2257, J1339+1310, and HE0435-1223, have been compared with simulated ones. The simulations are based on three BLR models, a Keplerian disk (KD), an equatorial wind (EW), and a polar wind (PW), with different sizes, inclinations, and emissivities. The models that best reproduce the observed line profile distortions were identified using a Bayesian probabilistic approach. We find that the wide variety of observed line profile distortions can be reproduced with microlensing-induced distortions of line profiles generated by our BLR models. For J1131, J1226, and HE0435, the most likely model for the Mg II and Hα BLRs is either KD or EW, depending on the orientation of the magnification map with respect to the BLR axis. This shows that the line profile distortions depend on the position and orientation of the isovelocity parts of the BLR with respect to the caustic network, and not only on their different effective sizes. For the Mg II BLRs in J1355 and J1339, the EW model is preferred. For all objects, the PW model has a lower probability. As for the high-ionization C IV BLR, we conclude that disk geometries with kinematics dominated by either Keplerian rotation or equatorial outflow best reproduce the microlensing effects on the low-ionization Mg II and Hα emission line profiles. The half-light radii of the Mg II and Hα BLRs are measured in the range of 3 to 25 light-days. We also confirm that the size of the region emitting the low-ionization lines is larger than the region emitting the high-ionization lines, with a factor of four measured between the sizes of the Mg II and C IV emitting regions in J1339. Unexpectedly, the microlensing BLR radii of the Mg II and Hα BLRs are found to be systematically below the radius-luminosity (R − L) relations derived from reverberation mapping, confirming that the intrinsic dispersion of the BLR radii with respect to the R − L relations is large, but also revealing a selection bias that affects microlensing-based BLR size measurements. This bias arises from the fact that, if microlensing-induced line profile distortions are observed in a lensed quasar, the BLR radius should be comparable to the microlensing Einstein radius, which varies only weakly with typical lens and source redshifts.

Recent studies have shown that line profile distortions are commonly observed in gravitationally lensed quasar spectra. We investigate the effect of gravitational microlensing on quasar broad emission line profiles and their underlying continuum, combining the emission from simple representative BLR models with generic microlensing magnification maps. Specifically, we considered Keplerian disk, polar, and equatorial wind BLR models of various sizes. The effect of microlensing has been quantified with four observables: $\mu^{BLR}$, the total magnification of the broad emission line; $\mu^{cont}$, the magnification of the underlying continuum; as well as red/blue, RBI and wings/core, WCI, indices that characterize the line profile distortions. The simulations showed that distortions of line profiles, such as those recently observed in lensed quasars, can indeed be reproduced and attributed to the differential effect of microlensing on spatially separated regions of the BLR. While the magnification of the emission line $\mu^{BLR}$ sets an upper limit on the BLR size and, similarly, the magnification of the continuum $\mu^{cont}$ sets an upper limit on the size of the continuum source, the line profile distortions mainly depend on the BLR geometry and kinematics. We thus built (WCI,RBI) diagrams that can serve as diagnostic diagrams to discriminate between the various BLR models on the basis of quantitative measurements. It appears that a strong microlensing effect puts important constraints on the size of the BLR and on its distance to the high-magnification caustic. In that case, BLR models with different geometries and kinematics are more prone to produce distinctive line profile distortions for a limited number of caustic configurations, which facilitates their discrimination.

Microlensing of the broad emission line region (BLR) in gravitationally lensed quasars produces line profile distortions that can be used to probe the BLR size, geometry, and kinematics. Based on single-epoch spectroscopic data, we analyzed the C IV line profile distortions due to microlensing in two quasars, SDSS J133907.13+131039.6 (J1339) and SDSS J113803.73+031457.7 (J1138), complementing previous studies of microlensing in the quasars Q2237+0305 and J1004+4112. J1339 shows a strong, asymmetric line profile deformation, while J1138 shows a more modest, symmetric deformation, confirming the rich diversity of microlensing-induced spectral line deformations. To probe the C IV BLR, we compared the observed line profile deformations to simulated ones. The simulations are based on three simple BLR models, a Keplerian disk (KD), an equatorial wind (EW), and a polar wind (PW), of various sizes, inclinations, and emissivities. These models were convolved with microlensing magnification maps specific to the microlensed quasar images, which produced a large number of distorted line profiles. The models that best reproduce the observed line profile deformations were then identified using a Bayesian probabilistic approach. We find that the line profile deformations can be reproduced with the simple BLR models under consideration, with no need for more complex geometries or kinematics. The models with disk geometries (KD and EW) are preferred, while the PW model is definitely less likely. In J1339, the EW model is favored, while the KD model is preferred in Q2237+0305, suggesting that various kinematical models can dominate the C IV BLR. For J1339, we find the C IV BLR half-light radii to be r1/2 = 5.1−2.9+4.6 light-days and r1/2 = 6.7−3.8+6.0 light-days from spectra obtained in 2014 and 2017, respectively. They do agree within uncertainties. For J1138, the amplitude of microlensing is smaller and more dependent on the macro-magnification factor. From spectra obtained in 2005 (single epoch), we find r1/2 = 4.9−2.7+4.9 light-days and r1/2 = 12−8+13 light-days for two extreme values of the macro-magnification factor. Combining these new measurements with those previously obtained for the quasars Q2237+0305 and J1004+4112, we show that the BLR radii estimated from microlensing do follow the C IV radius–luminosity relation obtained from reverberation mapping, although the microlensing radii seem to be systematically smaller, which could indicate either a selection bias or a real offset.

A CCD-line module is built to upgrade conventional spectrograph to the CCD ability of advanced data acquisition as well as a cost-effective solution to the plasma diagnostic spectroscopy measurement needs. The CCD module is adapted to the ISP-51 (Lomo-Russia) spectrograph, used for light dispersion and as a wavelength pre-selector when a Fabry-Perot interferometer is positioned into the parallel optical path of the spectrograph. A high-resolution spectrometer system is developed both computerized and easy to maintain. The main advantage over conventional method of spectral line profile registration is achievement of single-shot capability. Thus the line profile distortions caused by intensity fluctuations, which occur during the scanning process are eliminated. The capability of the designed spectrometer are presented with the measurements of the resolved superfine structure of the Cd I 480 nm spectral line profile as well as analyzing Ar I 738.4 nm spectral line profile broadening resulting with the gas temperature determination of argon inductively coupled plasma at low pressure and applied power.

We show that invaluable information on the structure quasar outflows can be obtained by considering microlensing (ML)-induced variability of absorption-line troughs in lensed quasars. Depending on the structure and geometry of the outflowing gas, such extrinsic line variability is manifested as changes to the equivalent width of the trough as well as line profile distortions. Here we consider several physically distinct outflow models having very similar spectral predictions, and show how ML-induced absorption-line variability can be used to distinguish between them. Possible merits from future systematic studies of these effects are exemplified.

Line profile distortions are commonly observed in gravitationally lensed quasar spectra. These distortions are caused by microlensing from the stars in the lensing galaxy, which produce differential magnification of spatially and kinematically separated parts of the broad line region (BLR). The quasi-simultaneous visible and near-infrared spectroscopy of the lensed quasar Q2237+0305 reveals strong microlensing-induced line deformations in the high-ionization C IVλ1549 Å and the low-ionization Hα emission lines. We use this effect to constrain the BLR size, geometry, and kinematics in Q2237+0305. For this purpose, we modeled the deformation of the emission lines for three representative BLR models: a Keplerian disk, an equatorial wind, and a biconical polar wind. We considered various inclinations with respect to the line of sight. We find that the observed microlensing effect, characterized by a set of four indices, can only be reproduced by a subsample of the considered BLR models. The microlensing analysis favors a Keplerian disk model for the regions emitting the C IV and the Hα emission lines. A polar wind model remains possible for the C IV BLR, although it is less likely. The equatorial wind model is totally excluded. A preferred inclination of the BLR of 40° is found, in agreement with expectations for a type 1 AGN and past constraints on the accretion disk inclination. The half-light radius of the BLR is r1/2 ≃ 47 ± 19 light-days, with no significant difference between the C IV and Hα BLRs. The size of the C IV BLR agrees with the radius-luminosity relation derived from reverberation mapping, while the size of the Balmer line BLR is one order of magnitude smaller, possibly revealing different quasar properties at high luminosities and high accretion rates.

Powerful and tunable lasers in the visible region are expected to be realized in the very near future, for the purpose of laser isotope separation and applications of tunable dye lasers, not only in our country but also in the United States and Europe. However, it is not so easy to realize both high power or energy and good tunability.In this paper, we wish to report an investigation of verious types of high-power tunable dye lasers which can be used as a pumping source for atomic uranium isotope enrichment, and high power techniques of dye laser apparatus, especially flashlamp-pumped high energy dye lasers developed in our laboratory.

Interaction of some organic dyes with DNA induces fluorescence enhancement through intercalation or groove binding, stimulating the development of compact tunable thin-film dye lasers. We have demonstrated amplified spontaneous emission (ASE), laser emission and its tuning via distributed feedback (DFB) with a dynamic grating formed in DNA-surfactant complexes doped with cyanine or hemicyanine dyes. The formation of semi-persistent (or quasi-dynamic) grating is more preferable in order to realize stable and easily tunable laser sources, so we fabricated bi-layered devices composed of a DNA-CTMA layer doped with pyridine 1 (Py1) and an PMMA layer including an azo dye, Disperse Red 1 (DR1). Under simultaneous excitation of the azo layer with interfering two beams for grating formation and the emission layer with another beam as pumping, we observed laser emission from the device. The oscillation wavelength was controlled by varying the incident beam angles allowing the fast tuning suitable to applications. Furthermore, monolithic DNA device having two functions of lasing and grating formation would be more promising. DNA-CTMA complex had been considered to be a poor matrix for grating inscription, but we found that doping of an azo-carbazole compound made it possible to inscribe gratings with relatively high diffraction efficiency and with fast response which could be applicable to monolithic tunable laser system.

Many new effects in optical physics and spectroscopy owe their origin to tunable dye lasers. Even if more practical and efficient tunable lasers are developed in the future, the remarkable role of the dye lasers in the advancement of science and technology cannot be overestimated. I would like to illustrate this statement with the example of the discovery of the methods for manipulating atomic motion by means of laser radiation, particularly the methods of the laserinduced optics of atomic beams. Incidentally, this area of laser-atomic physics will also be twenty five in two years. My interest in this problem was aroused in 1968 in connection with the search for new Doppler-free laser spectroscopic techniques. In the sixties, new Doppler-free laser absorption saturation spectroscopic methods were developed on the basis of the Lamb dip [11.1] and the inverted Lamp dip [11.2]. A shortcoming of this powerful technique is that it is capable of eliminating the linear Doppler broadening only in the quantum transition being saturated and in those coupled to it. I was aware of the fact that a principally different method existed to suppress the Doppler broadening, based on the restriction of the particle's motion within an area less than about 2 (radiation wavelength) across. This effect, referred to as the Lamp-Dicke regime [11.3], was successfully realized in the microwave band in the Ramsey hydrogen maser (storage bulb method) [11.4]. To implement such an approach in the optical region of the spectrum, I suggested [11.5] trapping atoms or molecules in small regions of space, less than ~'opt in size, by means of the so-called spatially periodic gradient force in a standing light wave (Fig. 11.1a). Thanks to the restriction (localization) of the atomic motion, there should have taken place a severe distortion of the Doppler profile with a narrow peak in its center, of all spectral lines observed along the axis of the standing light wave. I believed this method to hold much promise for high-resolution laser spectroscopy (in addition to saturation spectroscopy [11.1, 2] and two-photon spectroscopy in counter-propagating waves [ 11.6]) and called it the spectroscopy of trapped particles [11.7]. However, this idea, attractive as it was, could not be carried into effect without tunable lasers. I remember how, at the beginning of my research work at the Institute of Spectroscopy, Dr. O. Kompanets and myself made an attempt to

Tunable Lasers Handbook

Organic lasers came into existence via the introduction of the pulsed optically-pumped liquid organic dye laser by Sorokin and Lankard (1966) and Schafer et al. (1966). An additional momentous contribution was the discovery of the continuous wave (CW) liquid organic dye laser by Peterson et al. (1970) which opened the way for the development of narrow-linewidth tunability in the CW regime plus the eventual introduction of femtosecond lasers (see, for example, Dietel et al. (1983) and Diels, (1990)). The narrowlinewidth tunable pulsed dye laser was demonstrated by Hansch (1972) and improved by Shoshan et al. (1977), Littman and Metcalf (1978), Duarte and Piper (1980, 1981). All these developments in practical organic tunable lasers, spanning the visible spectrum, “created a renaissance in diverse applied fields such as medicine, remote sensing, isotope separation, spectroscopy, photochemistry, and other analytical tasks” (Duarte et al. (1992)). An early development, in the field of tunable lasers, was also the discovery of solid-state pulsed optically-pumped organic dye lasers by Soffer and McFarland (1967) and Peterson and Snavely (1968). However, it was not until the 1990s that, due to improvements in the dye-doped polymer gain media, this class of lasers would again be the focus of research attention (see, for example, Duarte (1994), Maslyukov et al. (1995), Costela et al. (2003)). An additional effort in optically-pumped tunable laser research is the work on organic semiconductor lasers based on thin-film conjugated polymers (see, for example, Holzer et al. (2002)). All this activity has been conducted on optically-pumped organic lasers although researchers from the onset have also been interested on the direct electronic excitation of tunable organic lasers (Steyer and Schafer, 1974; Marowsky et al., 1976). Some recent reviews mentioning efforts towards realizing coherent emission from direct electrical excitation of organic semiconductors, include Kranzelbinder and Leising (2000), Baldo et al. (2002), Samuel and Turnbull (2007), and Karnutsch (2007). Most of these reviews give ample attention to conjugated polymer gain media. In this chapter, experimental results demonstrating coherent emission from electricallyexcited pulsed dye-doped organic semiconductors, in microcavity configurations, are reviewed. The reported emission is single-transverse-mode, and given the 300 nm cavity length, also single-longitudinal mode. In the spectral domain the emission is indistinguishable

We show that it is possible to make a hologram with true-height contours by using dispersion compensation provided by holographic gratings in the reference and picture beams. Holograms can be made with either a short-pulse, mode-locked laser or a tunable dye laser with 2N + 1 frequencies each spaced by Δν frequency. Experiments are presented to illustrate the high-contrast contours obtained with consecutive exposures from a tunable dye laser. Fine-scale vernier and coarse contours are obtained at intervals c/[2(2N + 1)Δν] and c/(2Δv), respectively.

Theories of planet formation predict the birth of giant planets in the inner, dense, and gas-rich regions of the circumstellar disks around young stars. These are the regions from which strong CO emission is expected. Observations have so far been unable to confirm the presence of planets caught in formation. We have developed a novel method to detect a giant planet still embedded in a circumstellar disk by the distortions of the CO molecular line profiles emerging from the protoplanetary disk's surface. The method is based on the fact that a giant planet significantly perturbs the gas velocity flow in addition to distorting the disk surface density. We have calculated the emerging molecular line profiles by combining hydrodynamical models with semianalytic radiative transfer calculations. Our results have shown that a giant Jupiter-like planet can be detected using contemporary or future high-resolution near-IR spectrographs such as VLT/CRIRES or ELT/METIS. We have also studied the effects of binarity on disk perturbations. The most interesting results have been found for eccentric circumprimary disks in mid-separation binaries, for which the disk eccentricity - detectable from the asymmetric line profiles - arises from the gravitational effects of the companion star. Our detailed simulations shed new light on how to constrain the disk kinematical state as well as its eccentricity profile. Recent findings by independent groups have shown that core-accretion is severely affected by disk eccentricity, hence detection of an eccentric protoplanetary disk in a young binary system would further constrain planet formation theories.

We report a highly efficient, compact low-cost tunable dye laser pumped directly by green laser diodes. A tunable dye laser quasi-longitudinally pumped by two multimode InGaN diodes (520 nm), was implemented in a 200 ns pulsed mode with a 2 Hz repetition frequency. The lasing threshold energies were found to be 0.23–0.37 $$\upmu \hbox {J}$$ using an output mirror with 13% transmission. The best efficiency at the lasing maximum for Pyrromethene 567 exceeded 25% when the slope efficiency in broadband cavity configuration was 43% at an absorbed pump energy of $$0.75\,\upmu \hbox {J}$$ . The laser overlapped a wide spectral region of 145 nm (from 537 to 682 nm) with a linewidth of 1 nm. This indicates that green diodes can be used as an effective pump source for tunable dye lasers. Such lasers will be useful for spectroscopy, medicine and other fields due to their compactness and low cost.

A method to set accurately an etalon-tuned dye laser to any preselected wavelength within its lasing region is presented. The method involves a unique procedure to determine accurately the etalon thickness, so that the correct etalon order can be found for each wavelength and corresponding etalon setting. An equation relating the dial reading on the optical mount of the intracavity etalon to lasing wavelength is derived and evaluated for the Chromatix CMX-4 pulsed tunable dye laser. The procedure used to evaluate the equation parameters is described in detail. After establishing the value of all the equation parameters, a comparison is made between lasing wavelengths as predicted by the equation and as experimentally determined using laser-induced impedance changes to detect spectral lines in hollow cathode lamps. Agreement is found to be better than ±0.05 Å for all spectral lines used, with 68% of the predicted wavelengths within ±0.02 Å of their actual values. The micrometer drive for the birefringent filter, used in the CMX-4 to select an etalon order, is also calibrated using a quadratic polynominal equation, which gives predictions better than ±0.25 Å for all wavelengths tried in the regions of 5890 Å to 6050 Å and 6350 Å to 6720 Å, corresponding to the dyes R6G and R640, respectively.