K.W. Nill

Double heterostructure Pb1‐xSnx Te–PbTe lasers with cw operation at 77 K

Diode lasers that operate cw at 77 K have been made from a Pb0.88Sn0.12 Te–PbTe double heterostructure grown by liquid phase epitaxy. Junction diffusion during growth has been prevented by the use of Tl‐doped PbTe substrates. The wavelength emitted in cw operation has been temperature tuned from 10.5 μm at 12 K to less than 8.2 μm at 80 K, a range of nearly 280 cm−1. The cw threshold current density increases from 1.6 × 103 A/cm2 at 12 K to 4.2 × 103 A/cm2 at 77 K. The measured cw power is 10 mW in four modes at 12 K (1.8 × 104 A/cm2) and 1.2 mW in a single mode at 77 K (7.5 × 103 A/cm2).

Tunable diode laser measurements of water vapour absorption line parameters

Tunable diode laser measurements of water vapour lines in the 5 μm region have been extended to include oxygen as well as nitrogen broadening. Positive pressure shifts of line positions have been observed for the first time in the v 2 band. Absolute calibration of a line position using the CO laser as a reference has also been carried out.

Infrared Spectroscopy of CO Using a Tunable PbSSe Diode Laser

The P(9) fundamental infrared absorption line of carbon monoxide at 2107.4 cm−1 has been studied with high resolution using a cw current tunable PbS0.82Se0.18 diode laser. Both the Doppler linewidth of 150 MHz and the absorption coefficient at line center of 2.1 cm−1/Torr at room temperature have been measured directly for the first time with an estimated resolution of 1% of the linewidth.

Obervation of Λ-doubling and Zeeman splitting in the fundamental infrared absorption band of nitric oxide

Abstract A high resolution infrared study of the R( 15 2 ) vibration-rotation transition in 14N16O has been performed using a narrow linewidth (≈ 1 MHz) tunable PbSSe semiconductor laser. Small splittings due to Λ-type doubling and the Zeeman effect have been fully resolved (resolution ≈a 5 × 107), limited only the Doppler width in the low pressure gas.

LASER EMISSION FROM METAL‐SEMICONDUCTOR BARRIERS ON PbTe AND Pb0.8Sn0.2Te

Laser emission is obtained from forward biased evaporated metal barriers on degenerate p‐PbTe and p‐Pb0.8Sn0.2Te at T=4.2°K. Metals with small work functions such as In, Pb, and Zn produce a degenerate inverted n‐type surface region on p‐type samples without chemical doping. Low‐threshold laser emission has been obtained from these barriers on p‐PbTe at λ = 6.4μ and from Pb barriers on p‐Pb0.8Sn0.2Te at λ = 15μ.

Tunable cw Pb0.98 Cd0.02S diode lasers emitting at 3.5 μm: Applications to ultrahigh‐resolution spectroscopy

Continuously tunable cw diode lasers that produce narrow‐line (1‐ to 10‐MHz linewidth) radiation in the 3.5‐μm region have been fabricated from Pb0.98Cd0.02S. Lasers operating at 10–20 K produced more than 1 mW of cw power distributed among several modes which could be tuned continuously > 1 cm−1 by adjusting the laser current. A spectral range of 30 cm−1 could be covered over the full operating range. Ultrahigh‐resolution (10−5 cm−1) spectra of H2CO have been obtained to demonstrate the potential application of these lasers to the identification of organic molecules by spectroscopy of their C–H stretch absorption bands.

High‐resolution spectroscopy using magnetic‐field‐tuned semiconductor lasers

Tunable laser spectroscopy measurements on low‐pressure gases have been performed using magnetic‐field‐tuned lead‐salt semiconductor diode lasers in the 4‐ to 7‐μm region. Use of magnetic field tuning in conjunction with the conventional current tuning is shown to significantly increase the versatility of diode lasers in high‐resolution spectroscopy. Details of the tuning characteristics for fields up to 90 kG are presented.

Observation of nuclear hyperfine splitting in the infrared vibration—rotation absorption spectrum of the no molecule

Abstract Nuclear hyperfine splitting of several absorption lines in the Q branch of the fundamental 2 Π 1 2 vibration—rotation band of 14 N 16 O has been observed using a turnable PbSSe semiconductor laser operating near 5.4μm

Line shape of the Doppler‐limited infrared magnetic rotation spectrum of nitric oxide

A fully resolved, Doppler‐limited magnetic rotation spectrum of the R (13/2)1/2 absorption line in the fundamental (ν = 0 → ν = 1) vibration‐rotation band of NO has been obtained using a cw, tunable PbSSe semiconductor diode laser.

Measurement of the Gain Line Shape of a Gas Laser Using a Tunable Semiconductor Laser

Using a cw tunable PbS0.6Se0.4 semiconductor diode laser operating near 5.3 μm we have fully resolved the gain (loss) line shape of several vibration‐rotation lines of a CO gas laser amplifier.