Travelling-wave-pumped ultrashort-pulse distributed-feedback dye laser

A travelling-wave pumping scheme is used to excite a distributed feedback dye laser. Output pulse shortening below the resolution limit of the streak camera system (1.9 ps) is observed when the velocity of the travelling pump wave is properly matched to the velocity of the laser emission. The pulse spectrum has been measured simultaneously. It consists of a single line of 4 Å width.     

Tunable distributed-feedback laser based on dye doped microporous quartz glass

The first distributed feedback (DFB) dye laser on the basis of microporous quartz glass (MQG) is reported. MQG consists of a specially processed quartz sample doped with a dye. As a pumping source a second harmonic YAG: Nd³⁺ laser with 12.5 pps repetition rate was used. Stable generation of the narrow line tuned within a spectral range of 562–584 nm and 633–663 nm with a linewidth of 0.04 nm was obtained. A high photochemical stability of the dye in the quartz matrix and reliability of MQG as an active medium for the tunable DFB laser were experimentally demonstrated.     

Sensitive absorption spectroscopy with a room-temperature distributed-feedback quantum-cascade laser

We report what we believe are the first spectroscopic measurements to be made with a room-temperature quantum-cascade distributed-feedback laser. Using wavelength modulation spectroscopy, we detected N(2)O and CH(4) in the chemical fingerprint wavelength range near 8microm . The noise equivalent absorbance for our measurement was 5 parts in 10(5), limited by excess amplitude modulation on the laser output, which corresponds to a 1-Hz bandwidth detection limit of 250 parts N(2)O in 10(9) parts N(2) in a 1-m path length.     

Doppler-limited dye laser excitation spectroscopy of HCF

The cw dye laser excitation spectrum of the $\text{A}\text{?}{}^1\text{A″(000) ←}\text{X}\text{?}{}^1\text{A′(000)}$ vibronic band of HCF was observed between 17 188 and 17 391 cm^?1 with the Doppler-limited resolution, 0.04 cm^?1. The HCF molecule was produced by the reaction of discharged CF₄ with CH₃F, and 853 lines were observed, of which 516 transitions were assigned to K′_a ← K″_a = 3 ← 4, 2 ← 3, 1 ← 2, 0 ← 1, 1 ← 0, 2 ← 1, 0 ← 0, 1 ← 1, 2 ← 2, 3 ← 3, 2 ← 0, and 0 ← 2 subbands. A rotational analysis yielded the rotational constants and quartic and sextic centrifugal distortion constants for both the $\text{A}\text{?}$ and $\text{X}\text{?}$ states and the band origin, with good precision. The molecular constants determined reproduce the observed transition frequencies with an average deviation of 0.0038 cm^?1. Small rotational perturbations in the excited state were found at J = 5, 6 and J = 10, 11 of J_1,J and at J = 15, 16 of J_2,J?1 levels.     

Doppler-limited dye laser excitation spectroscopy of DCF

The dye laser excitation spectrum of the vibronic transition of DCF was observed between 17 200 and 17 400 cm⁻¹ with the Doppler-limited resolution. DCF was produced by the reaction of microwave-discharged CF₄ with CD₃F. The observed spectra, which were found to be nearly free of perturbations, were assigned to 858 transitions of the K′_a − K″_a = 4−5, 3−4, 2−3, 1−2, 0−1, 1−0, 2−1, 3−2, 3−3, 2−2, 1−1, 0−0, 2−0, and 0−2 subbands, and were analyzed to determine the rotational constants and centrifugal distortion constants for both the and à states. The rotational constants of DCF thus determined were combined with those of HCF to calculate the structural parameters for this molecule: r(C---H) = 1.138 Å, r(C---F) = 1.305 Å, and HCF = 104.1° for the ground state, and r(C---H) = 1.063 Å, r(C---F) = 1.308 Å, and HCF = 123.8° for the excited à state.     

Doppler-limited dye laser excitation spectroscopy of HCCl

The cw dye laser excitation spectrum of the $\text{A}\text{?}{}^1\text{A″(050) ←}\text{X}\text{?}{}^1\text{A′(000)}$ vibronic band of HCCl was observed between 16 539 and 16 656 cm^?1 with the Doppler-limited resolution, 0.03 cm^?1. The HCCl molecule was generated by the reaction of discharged CF₄ with CH₃Cl. The observed spectra were assigned to c-type transitions with ΔK_a = ±1 and also to axis-switching transitions with ΔK_a = 0 or ?2, but all with K′_a = 0, both for HC³⁵Cl and HC³⁷Cl. A rotational analysis yielded the rotational constants and quartic centrifugal distortion constants for the ground vibronic state and the band origin. A weak vibronic band, about one-third as intense as the main band, was found at about 57 cm^?1 to the violet of the main band for both isotopic species, and was ascribed to a transition from the ground vibronic state to a vibrational level, possibly (041), of the à state. The rotational levels of HC³⁵Cl in the à state showed a large perturbation; the J′ = 8, 9, and 10 levels were found to be split into two components. A normal coordinate analysis was carried out to calculate the centrifugal distortion constants and the inertia defect, which were in fair agreement with the observed values. The molecular structure of HCCl in the ground vibronic state was recalculated from the rotational constants of the two isotopic species combined with the 0.75B₀ + 0.25C₀ value previously reported for DC³⁵Cl.     

Highly-efficient fully-fiberized mid-infrared differential frequency generation source and its application to laser spectroscopy

Widely-tunable, fully-monolithic, mid-infrared (mid-IR) deference frequency generation source (DFG) is presented. By using a custom designed fiber-pigtailed periodically poled lithium niobate (PPLN) crystal module the idler beam was generated with an efficiency of 21%/W, yielding 2.6 mW of optical output power. The proposed all-fiber configuration radically simplified the optical frequency conversion setup, making it robust and easily configurable. The usefulness of the constructed source was verified by performing simultaneous wavelength modulation spectroscopy (WMS) laser trace gas detection of methane, near 2999 cm^?1, and ethane, near 2997 cm^?1, via two independently generated, tunable idler beams.     

Theory and experiment of CW dye laser injection locking and its application to second harmonic generation

High-power single-mode operation of a cw ring dye laser has been obtained by injection of cw single-mode radiation. The intracavity power of this system was used to generate tunable single-mode uv radiation by frequency doubling in a temperature phase-matched ADA crystal: up to 45 W intracavity fundamental power and up to 70 mW extracted uv power have been observed. A theoretical treatment of the injection locked cw ring dye laser system is given for the stationary state. Expressions for the intracavity intensities as a function of the small-signal gain and the saturation intensity are derived.     

Design of a dye laser for nonlinear spectroscopy

Special requirements should be met by a pulsed dye laser in order to provide reproducible data in a nonlinear experiment. The cavity and pumping laser are chosen to minimize effects due to detailed dye characteristics. A suitable ruby pumping laser is described.     

Opto-acoustic spectroscopy with a visible CW dye laser

The first use of a tunable visible laser in conjunction with an opto-acoustic cell is described. By using a longitudinal resonance of the gas cell NO₂ can be detected around 10 p.p.b., the same order of detectivity as in the infrared. The use of the technique for studying photodissociation in the visible and u.v. is discussed.     

Coherent spectroscopy with a distributed feedback dye laser

A simple and flexible distributed feedback dye laser source pumped by the harmonic of a mode-locked YAG laser is described. Measurements of dephasing times of isotopic and hot bands in CS₂ liquid exploiting both the frequency and time-resolution of this source are reported.     

CVL-pumped dye laser for spectroscopic application

A spectroscopic dye laser system-pumped by a Copper Vapor Laser (CVL)-has been built and optimized for different dye solutions operating in the spectral range from 530 to 890 nm. Conversion efficiencies up to 40% were reached in broad band operation, 24% with a prism expander grating cavity, and 20% in grazing incidence configuration, which operated at typical band widths of 3 GHz. Second harmonic generation (SHG) of the dye laser output produced tunable uv-radiation between 260 and 408 nm at conversion efficiencies 5%. Fundamental and SHG output were used for resonant ionization experiments in molecular beams.     

Four-beamlets laser array and its propagation

A new type of laser array named four-beamlets laser array is proposed. Based on the diffraction integrals, analytical propagation formulae for the four-beamlets laser array passing through paraxial aligned and misaligned optical systems are derived, respectively. The four-beamlets laser array can also be expressed as a superposition of a series of Hermite Gaussian modes by using polynomial expansion. As a numerical example, the propagation properties of a four-beamlets laser array in free space are illustrated graphically. The fractional Fourier transform of the four-beamlets laser array is also studied. Our model provides a convenient way to describe laser array with four-beamlets.     

面发射分布反馈半导体激光器及光栅耦合半导体激光器

阐述了以曲线光栅面发射分布反馈半导体激光器（SEDFB）为代表的SE—DFB器件的原理和结构,讨论了它们的性能和特点并与其他类型的半导体激光器进行了比较。指出依靠曲线光栅特殊的衍射特性,可实现对模式的控制和二维漏模耦合阵列化出光,得到窄线宽（典型值0．08nm）、小发散角（典型值0．5mrad）、高亮度（单管近衍射极限3W（CW））和大功率（单管最高73w,列阵为kW级）的激光。综述了SE—DFB的发展历程、现状及未来的发展趋势,强调由于曲线光栅耦合SE—DFB激光器兼具边发射和面发射器件的优势和诸多其他优秀性能,将其应用于不同材料体系,不同结构的半导体激光器及其阵列,制作不同波段的高功率、高光束质量的SEDFB器件会有很好的研究意义和应用前景。     

Doppler-limited dye laser excitation spectroscopy of the CCN radical

The cw dye laser excitation spectrum of the $\text{A}\text{?}{}^2\text{Δ}\text{(000) ←}\text{X}\text{?}{}^2\text{Π}\text{(000)}$ vibronic transition of the CCN radical was observed between 21 205 and 21 335 cm^?1 with the Doppler-limited resolution, 0.04 cm^?1. The CCN radical was produced by reaction of microwave discharged CF₄ with CH₃CN. The observed spectrum was analyzed to determine rotational and centrifugal constants and effective spin-orbit and spin-rotation coupling constants for both the $\text{A}\text{?}{}^2\text{Δ}\text{(000)}$ and the $\text{X}\text{?}{}^2\text{Π}\text{(000)}$ states, and also the Λ-type doubling constants for the $\text{X}\text{?}{}^2\text{Π}\text{(000)}$ state. The constants determined reproduce the observed spectrum with an average deviation of 0.0027 cm^?1, and are considered to be precise enough for predicting the ground-state microwave transition frequencies. No evidence was found for perturbation in either the $\text{A}\text{?}{}^2\text{Δ}\text{(000)}$ or the $\text{X}\text{?}{}^2\text{Π}\text{(000)}$ state.     

Doppler-limited dye laser excitation spectroscopy of the DSO radical

The $\text{A}\text{?}{}^2\text{A′(003) ←}\text{X}\text{?}{}^2\text{A″(000)}$ vibronic transition (16 370 to 16 425 cm^?1) of the DSO radical in studied by Doppler-limited dye laser excitation spectroscopy. DSO is produced in a flow system by reacting the products of a microwave discharge in O₂ with D₂S. About 637 observed lines are assigned to 987 transitions of the 19 subbands: K′_a ← K″_a = 6 ← 5, 5 ← 4, 4 ← 3, 3 ← 2, 2 ← 1, 1 ← 0, 0 ← 1, 1 ← 2, 2 ← 3, 3 ← 4, 0 ← 0, 1 ← 1, 2 ← 2, 3 ← 3, 4 ← 4, 3 ← 1, 2 ← 0, 0 ← 2, and 1 ← 3. They are analyzed to determine rotational constants, centrifugal distortion constants, and spin-rotation constants for both the ground and the excited electronic states. The band origin obtained is 16 413.874 (2.5σ = 0.002) cm^?1. The rotational constants determined are combined with the previous result on HSO (M. Kakimoto et al., J. Mol. Spectrosc.80, 334–350 (1980)) to calculate the structural parameters for this radical in both the states: $\text{r(}\text{SO}\text{) = 1.494(5)}\text{A}\text{?}$, $\text{r(}\text{SH}\text{) = 1.389(5)}\text{A}\text{?}$, and ∠HSO = 106.6(5)° for the $\text{X}\text{?}{}^2\text{A″}$ state, and $\text{r(}\text{SO}\text{) = 1.661(10)}\text{A}\text{?}$, $\text{r(}\text{SH}\text{) = 1.342(8)}\text{A}\text{?}$, and ∠HSO = 95.7(21)° for the $\text{A}\text{?}{}^2\text{A′(003)}$ state, where values in parentheses denote 2.5σ.     

Doppler-limited dye laser excitation spectroscopy of the HSO radical

The cw dye laser excitation spectrum of the vibronic transition of the HSO radical was observed between 16 420 and 16 520 cm⁻¹ with Doppler-limited resolution, 0.03 cm⁻¹. The HSO radical was produced by reaction of discharged oxygen with H₂S or CH₃SH. The observed spectra were assigned to 751 transitions of the K′_a ← K″_a = 2 ← 3, 1 ← 2, 0 ← 1, 1 ← 0, 2 ← 1, and 3 ← 2 subbands, and were analyzed to determine rotational constants, centrifugal distortion constants, and spin-rotation interaction constants with good precision. The signs of the spin-rotation interaction constants were determined for both the upper and the lower state from the observed spectra. The band origin obtained is 16 483.0252 (2.5σ = 0.0013) cm⁻¹. The molecular constants which were determined reproduce the observed transitions with an average deviation of 0.0045 cm⁻¹.