This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

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The HITRAN 2008 molecular spectroscopic database

Reviews the basic physics of tunable solid-state lasers and discusses the characteristics of the most significant established and emerging systems. Particular emphasis is placed on trivalent transition metals; alexandrite, other Cr-doped systems, and Ti: sapphire are also discussed. Other systems, rare earth and forsterite, are considered. >

Tunable solid-state lasers

Models for numerical simulations of laser-pumped thulium- and thulium-holmium-doped lasers have been developed. In the models, upconversion losses and ground-state depletion in both thulium and holmium are accounted for, as well as spatial dependencies of the pump and resonator modes. The models apply to CW operation and to the build-up of population inversion prior to lasing in pulsed modes of operation. It is shown that upconversion losses in Tm:Ho:YAG significantly reduce the output from the laser in both CW and Q-switched mode. Simulations of CW lasers show good agreement with experimental results.

Modeling of laser-pumped Tm and Ho lasers accounting for upconversion and ground-state depletion

A novel chaotic lidar (CLIDAR) system that utilizes a chaotic laser as the light source is proposed and studied. In CLIDAR, the detection and ranging are realized by correlating the signal waveform reflected back from the target with a delayed reference waveform. Benefiting from the very broad bandwidth of the chaotic waveform that can be easily generated by a semiconductor laser, a centimeter-range resolution is readily achieved. The correlation performance of CLIDAR is studied both numerically and experimentally. The power spectra, phase portraits, time series, and correlation traces of the chaotic waveforms obtained at different operating conditions are compared. The relation between the complexity of the attractor and the correlation property is examined. The correlation dimension and the largest positive Lyapunov exponent of each waveform are calculated. To compare the correlation performance of the waveforms quantitatively, peak sidelobe levels of the correlation traces with different correlation lengths and relative noise levels are investigated. Preliminary experiments show a subcentimeter accuracy in ranging with a 3-cm-range resolution, which currently is limited by the bandwidth of the oscilloscope used.

Chaotic lidar

Stable and self-starting mode-locking of a Tm:KLu(WO4)2 crystal laser is demonstrated using a transmission-type single-walled carbon nanotube (SWCNT) based saturable absorber (SA). These experiments in the 2 µm regime utilize the E11 transition of the SWCNTs for nonlinear saturable absorption. The recovery time of the SWCNT-SA is measured by pump-probe measurements as ~1.2 ps. The mode-locked laser delivers ~10-ps pulses near 1.95 µm with a maximum output power of up to 240 mW at 126 MHz repetition rate.

Passive mode-locking of a Tm-doped bulk laser near 2 microm using a carbon nanotube saturable absorber.

The use of airborne laser radar (lidar) to measure wind velocities and to detect turbulence in front of an aircraft in real time can significantly increase fuel efficiency, flight safety, and terminal area capacity. We describe the flight-test results for two coherent lidar airborne shear sensor (CLASS) systems and discuss their agreement with our theoretical simulations. The 10.6-μm CO2 system (CLASS-10) is a flying brassboard; the 2.02-μm Tm:YAG solid-state system (CLASS-2) is configured in a rugged, lightweight, high-performance package. Both lidars have shown a wind measurement accuracy of better than 1 m/s. © 1996 Optical Society of America

Coherent lidar airborne wind sensor II: flight-test results at 2 and 10 νm.

Injection control of a tunable Ti:sapphire laser using a narrow-bandwidth pulsed dye laser operating at a wavelength removed from the peak of the Ti:sapphire-laser gain curve is reported. The free-running Ti:sapphire laser had broadband laser emission from 750 to 790 nm. Injection at 727 nm resulted in essentially complete energy extraction at that wavelength in a 2.5-pm bandwidth matching the injection source.

Pulsed injection control of a titanium-doped sapphire laser.

High resolution spectra in the region of the v(2) band of nitric acid have been obtained for selected portions of the HNO(3) spectrum using tunable diode laser techniques. Continuous spectra are presented from 1718.97 cm(-1) to 1729.57 cm(-1), with a spectral resolution </=0.001 cm(-1) (30 MHz). Absolute line intensities and line positions are presented. Self- and foreign-gas (N(2)) broadening coefficients were iteratively calculated from the experimental data and were determined to be alpha(a) = 0.74 cm(-1)/atm and alpha(f) = 0.13 cm(-1)/atm, respectively.

High-resolution spectral measurement of the HNO(3) 5.9-microm band using a tunable diode laser.

Theoretical and experimental frequency narrowing studies of a Ti-sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported. >

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

Knowledge of the temperature distribution of laser rods end pumped by laser diodes or other laser systems is relevant when thermal stress and crystal damage are expected. The temperature of a multipulsed or continuously pumped laser rod is given as a double-series expression and as a function of time. The mathematical model considers all surface cooling rates, the spatial and temporal variations of the pump beam, and the specific heat and thermal conductivity of the rod material. This eigenfunction expansion representation was employed to predict the spatial and time-dependent quasi-steady-state temperature in Ti:sapphire, Nd:YAG, and Cr:LiSAF laser rods of specific dimensions.

P. Brockman

Papers

Coherent lidar airborne wind sensor II: flight-test results at 2 and 10 νm.

Pulsed injection control of a titanium-doped sapphire laser.

High-resolution spectral measurement of the HNO(3) 5.9-microm band using a tunable diode laser.

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

Temperature distribution in side- and end-pumped laser crystal rods: temporal and spatial variations