A. Javan

The MOM tunneling diode - Theoretical estimate of its performance at microwave and infrared frequencies

A theoretical analysis of the metal‐oxide‐metal (MOM) antenna/diode as a detector of microwave and infrared radiation is presented with the experimental verification conducted in the far infrared. It is shown that the detectivity at room temperature can be as high as 1010 W−1 Hz1/2 at frequencies of 1014 Hz in the infrared. As a result, design guidelines are obtained for the lithographic fabrication of thin‐film MOM structures that are to operate in the 10‐μ region of the infrared spectrum.

FREQUENCY MIXING IN THE INFRARED AND FAR‐INFRARED USING A METAL‐TO‐METAL POINT CONTACT DIODE

Metal‐to‐metal point contact diodes were used to obtain the 54‐GHz beat notes between two adjacent 10.6‐μ CO2 laser transitions. The speed of the diodes in the far‐infrared is at least 1000 GHz. This was tested with a 337‐μ HCN laser.

ABSOLUTE FREQUENCY MEASUREMENT AND SPECTROSCOPY OF GAS LASER TRANSITIONS IN THE FAR INFRARED

Absolute frequencies of the 311‐μ and the 337‐μ transitions of the CN gas laser are measured to within a few parts in 107. This is achieved by mixing the laser frequencies with high order harmonics of a microwave signal in a silicon diode. The beat frequencies of these two transitions which falls at 73.5 GHz is also measured directly. The Zeeman effect of these two laser transitions is studied. Based on a detailed analysis, it is found that the existing identification of these transitions is inconsistent with our observations.

Collisional narrowing of infrared water‐vapor transitions

Water‐vapor absorption lines in the ν2 band involving transitions between states of high rotational energy have been found to undergo substantial collisional narrowing in the presence of buffer gases. Measurements were carried out near 5.35 μm, using tunable lead sulfide selenide semiconductor diode lasers.

6A5 - Possibility of self-focusing due to intensity dependent anomalous dispersion

Close to an atomic resonance, the dependence of the real part of the susceptibility on power level (i.e., saturation effects) can be sizeable and therefore lead to self-trapping or self-focusing. It is shown here under what conditions this effect can occur. Order of magnitude estimates are given for the intensity dependent index change and the diameter of the trapped beam for some laser materials.

EXTENSION OF LASER HARMONIC‐FREQUENCY MIXING TECHNIQUES INTO THE 9 μ REGION WITH AN INFRARED METAL‐METAL POINT‐CONTACT DIODE

An infrared point‐contact diode is used to mix the frequency of a 28.0 μ water laser with that of a 9.3 μ CO2 laser and a K‐band microwave radiation. The experiment provides, among several applications, the crucial link necessary to establish a frequency multiplier chain for absolute frequency measurements in the infrared.

Accurate laser wavelength measurement with a precision two-beam scanning Michelson interferometer

This paper gives the details of a precision two-beam scanning Michelson interferometer, designed and perfected for accurate comparison of an unknown laser wavelength and the precisely calibrated wavelength of a reference laser. An iodine Lamb-dip stabilized He-Ne 633-nm laser (calibrated with respect to a Kr standard) is used as the reference. The design incorporates features to minimize instrumental errors and the effect of fringe shifts caused by diffraction (in the IR). It is applied to accurate measurements of a stable CO(2) laser wavelength tuned to the centers of its various transitions. Measurements are done by simultaneous fringe counting and relative fringe-phase comparison at the two wavelengths using on-line data storage and processing with an electronic digital computer. The accuracy in the 10-microm region is several parts in 10(9) and is limited by correction for diffraction fringe shifts. Because of its low-Q and broadband operating characteristics, it can be applied to rapid accurate laser wavelength measurements over the entire wavelength range permitted by its transmitting optics. In the visible range where the diffraction correction is small, the interferometer can be used to perform measurements to within several parts in 10(11). The paper gives theoretical derivation of various diffraction corrections, the design and construction of the interferometer, the alignment procedures, detailed analysis of various error sources, and data processing. It also gives the details of a previously reported accurate measurement of the speed of light using the measured wavelength of the CO(2) R(14) line and its known frequency.

ERRATA: STANDING WAVE SATURATION RESONANCES IN THE CO2 10.6‐μ TRANSITIONS OBSERVED IN A LOW‐PRESSURE ROOM‐TEMPERATURE ABSORBER GAS

The standing‐wave saturation resonances are observed by subjecting the CO2 absorber gas to the standing‐wave 10.6‐μ laser field and detecting the change induced in the entire 4.3‐μ (001) → (000) spontaneous emission band as the laser frequency is tuned within the Doppler profile of a specific 10.6‐μ transition. Long‐term stabilization on any oscillating transition is achieved.

ac electron tunneling at infrared frequencies: Thin‐film M‐O‐M diode structure with broad‐band characteristics

A high‐speed diode element consisting of a metal‐metal‐oxide‐metal electron‐tunneling junction is formed by thin films deposited on a substrate. These junctions are integrated with deposited narrow resonant antenna structures which couple the junction to incident radiation. Broad‐band characteristics from radio and microwave frequencies to the infrared region are shown. Frequency mixing and the possibility of utilizing large numbers of elements simultaneously are also demonstrated.

Measurement of vibrational-vibrational exchange rates for excited vibrational levels (2≤v≤4) in hydrogen fluoride gas

A measurement of the total decay rate (due to both V-V and V-T processes) of the second, third, and fourth vibrational levels in vibrationally cold hydrogen fluoride gas is described. The measured endothermic rate constants are 8×105, 1.6×106, and 1.4×106 sec−1 · torr−1, respectively. It is argued that the major contribution of each of these decay rates is from the process HF(ν = n)+HF(ν = 0)→ HF(ν = n − 1) + HF(ν = 1) where n = 2,3, and 4. The technique used in these measurements is a novel variation of the method of laser induced fluorescence. It involves exciting the first; first and second; or first, second, and third vibrational levels of HF via multiband laser optical pumping. Collisional population of the level of interest then occurs through the reverse of the above vibrational exchange process. An analysis using rate equations shows that the rise rate of the population of a given level is governed by the forward rate of the above process. It is also shown theoretically and experimentally that in ...