Jerald R. Izatt

Continuously tunable CH 3 F Raman far-infrared laser

By pumping CH(3)F with a 150-mJ, continuously tunable, multiatmosphere CO(2) laser, we have produced approximately 0.2-mJ far-infrared laser pulses that can be tuned quasi-continuously over approximately 85% of the range from 220 to 400 microm. The tunable far-infrared laser action results from two-photon (Raman) transitions in the R branch of the CH(3)F nu(3) band.

One watt, far infrared CH3OH laser

Abstract Peak powers near 1 watt have been observed on the CH 3 OH laser line at 570.5 μm as well as on each of three new CH 3 OH laser lines produced by pumping a far infrared guided wave cavity with a 0.5 MW helical CO 2 -TEA laser. The new lines have wavelengths of 58.1, 65.1 and 451.9 μm. For all four lines the optimum CH 3 OH pressure was between 2.3 and 3 torr, and laser action at 65.1 μm persisted up to a pressure in excess of 9 torr.

Paper sheet moisture measurements in the far infrared

Measurement of several parameters pertinent to process and quality control in the manufacture of paper products is a potentially important application of far-infrared lasers. Preliminary measurements of the transmittance and reflectance of moist paper sheets are presented, and their use to determine the percentage moisture content and the dry basis weight of the paper is discussed.

New CH3OH laser lines pumped with a fine-tuned high-power CO2-TEA laser

Joule-level pulses from an etalon tuned CO2-TEA laser with an ∼ 4GHz intraline tuning range have been used to pump a large number of new CH3OH FIR laser lines. FIR wavelength measurements, pump laser offsets which produced FIR laser lines and pump laser offsets at which CH3OH absorption lines were observed are reported. Identifications are proposed for most of the absorption lines, and an attempt to identify the FIR laser lines is described.

Fine frequency tuning of high power TEA CO2 lasers

Abstract A new technique is proposed to fine tune a TEA CO 2 laser within the bandwidth of a single ro-vibrational emission line. A tuning range of ±2 GHz off line center is obtained with an emission bandwidth of about 250 MHz and with a total energy output exceeding 1 joule at line center for the P20 (00°1–10°0) line. This technique can be used for single longitudinal mode operation and has the advantage of being directly scalable to higher power lasers.

Wavelengths for new CH3OH laser lines

Using a grating-tuned CO2-TEA laser to pump CH3OH in a metallic-wave-guide resonator, submillimeter laser emissions have been produced by pumping with 36 lines in the 9.4μm CO2 band and with 23 lines in the 10.6μm band. Several dozen new SMM laser lines were observed. Wavelengths accurate to within ∼0.1% are given for 12 previously unmeasured lines between 34μm and 225μm.

Q switching and mode locking of CO2 laser with aromatic halogenated hydrocarbons

Passive Q switching of the CO2 laser by a new class of saturable absorbers is reported. Results are presented for eight representatives of this class: benzene, chlorobenzene, bromobenzene, m‐dichlorobenzene o ‐dichlorobenzene, m ‐difluorobenzene, pentafluorobenzene, and hexafluorobenzene. These Q‐switching agents operate on a large number of lines in both the 9.6‐ and 10.6‐μ bands. Other aromatic halogens selected on the basis of their absorption spectra are expected to display similar Q‐switch characteristics. This new class of saturable absorbers provides increased flexibility in the production of CO2 laser pulses.

Intracavity double resonance in the CH 3 OH submillimeter laser

An intracavity double-resonance technique has been used to study three K-type doublets in the portion of the CH3OH torsional–rotational–vibrational level structure which can be pumped by the CO2 10R(38) laser line to produce submillimeter (SMM) laser action. Measurements of the doublet spacings yield a value of S(4) = 2.1(1) × 10−9 for the first excited state of the ν8 vibrational mode. Measurements of the pressure and rf power dependence of the amplitude and halfwidth of the double-resonance signals produce a new evaluation of the rotational relaxation rate and other useful information pertinent to SMM laser dynamics.

Laser frequency control by spectrally depleted destructive two-beam interference

Abstract We describe, and present experimental evidence to support, a new technique capable of producing sufficient frequency displacement and bandwidth compression to permit near perfect coincidence in frequency and width between the output of a CO 2 -TEA laser and a Doppler broadened absorption line. This is accomplished by replacing one of the laser end mirrors with a Michelson interferometer that is adjusted for destructive interference and by placing the absorbing gas in one of its arms.

Optimum spectral matching for a resonantly pumped far-infrared laser

Abstract A new interferometric technique is described for matching the central frequency and bandwidth of a CO 2 -TEA laser to a Doppler broadened absorption line in a far-infrared (f.i.r.) medium. Experimental results are presented which demonstrate a tuning range of more than 1 GHz for the TEA laser lines, TEA laser mode structure consistent with a bandwidth less than 100 MHz, and a large increase in f.i.r. laser pumping efficiency. Application of the technique to the realization of a continuously tunable, narrow bandwidth, multi-atmosphere CO 2 laser is discussed.