Shozo Kon

Stabilization of a CO2 pump laser using external CH3OH stark-cell modulation

In order to stabilize the 118.8 μm CH3OH laser output, frequency stabilization of the CW 9P(36) CO2 laser pump is carried out using external CH3OH Stark-cell modulation without internal frequency modulation. The CO2 laser output power around the CH3OH absorption center is stabilized to within ±1.0% for 60 min. The frequency stability of the CO2 laser is estimated to be within ±1.4 MHz for 60 min, assuming the output fluctuation to be caused by this frequency fluctuation. As a result of the CO2 pump laser stabilization, an output power stability of about ± 1.0% for 30 min is obtained for the 118.8 μm CH3OH laser.

Assignments of optically pumped CD3OH laser lines

Six FIR laser lines from CD3OH pumped by the 10R(36) and the 10R(18) CO2 laser lines are assigned to specific rotational energy levels in the excited C−0 stretch state. It is found that their upper laser levels are shifted by a Fermi resonance between the C−0 stretch vibration and the third and forth harmonics of the torsional mode. The Fermi resonance shifts are +0.332 cm−1 and +2.251 cm−1 for the upper laser levels pumped by the 10R(36) and the 10R(18) CO2 laser lines, respectively. Calculated frequencies of the pump and the laser transitions agree with those of the pump CO2 laser lines and the observed FIR laser lines within estimated accuracy.

Optically Pumped Far-Infrared Laser Lines in Deuterated Methyl Alcohol, CH3OD, CH2DOH, CHD2OH, CD3OH, CD3OD

Normal methyl alcohol(CH3OH) pumped by CO2 laser is known as the best FIR laser molecule. The exchage of H by D in the molecule does not shift the CO2 laser absorption appreciably; all of its deuterated species falls in the 900–1100 cm-1 region of CO2 laser spectrum. Laser action in CH3OD was first observed by Dyubko et al. in 1974, subsequently many new lines were reported by many authors.

High power FIR NH3 laser using a folded resonator

A compact FIR laser cavity having a couple of folding mirrors was designed. By inserting this FIR cavity into the pump TE CO2 laser resonator, we observed 19 FIR NH3 laser lines of which 4 new lines were included. The maximum output power was over 500 W at 90 μm.

Intracavity pumped far-infrared lasers by TE CO2 laser.

A novel compact FIR laser system was constructed. The FIR laser cavity was placed inside the resonator of a pump TE CO2 laser. With this system, FIR laser actions in D2O and CH3OH were observed. Five new lines were found in CH3OH.

Compact, high power FIR NH3 laser pumped in a three mirror CO2 laser cavity

A compact CO2−NH3 FIR laser system where an NH3 laser cavity was inserted in pump, three mirror CO2 laser cavity was designed. The total length of this system was about 1.8 m. Output energy of about 1 mJ (⊥10 KW pea power) was obtained at the 152 μm and 90 μm lines in NH3. Power conversion efficiency of 1.7 percent was obtained at the 90 μm line.

Experimental test of CH3OH laser line assignments with competitive and cascade couplings

Abstract Periodic reduction and enhancement are observed in the tuning curves of optically pumped CH3OH laser lines. It is shown that they are caused by competitive or cascade couplings. The interactions are found in four groups of the CH3OH laser lines pumped by the 9P(36), 9P(34), 9R(10) and 10R(38) CO2 laser lines. The proposed assignments of the laser lines are checked with the experimental results.

Mode Characteristics of TEA CO2 Laser Using an Unstable Resonator

An output spectrum of the TEA CO2 laser was observed with the use of a confocal Fabry-Perot interferometer. In output pulses, four or five longitudinal modes were found and they were oscillating independently. To obtain single mode oscillation, a Ge flat mirror or a butadiene absorption cell as a mode selector was placed in the unstable cavity. It was possible to determine the frequency of a single mode by using the Fabry-Perot interferometer.

Intracavity pumped NH3 laser using a very small cavity

Abstract A new FIR laser cavity (1 cm 3 active mode volume) which was as small as possible for intracavity pumping configuration was constructed. Though this cavity was very small, NH 3 laser action was observed in 13 lines. Comparison between intracavity pumping of the NH 3 laser suggests how to make a high power FIR laser of a compact cavity.

Forced CO2 Laser Oscillation by Injection of a Weak External Optical Signal

A forced or frectuency locked oscillation is obtained even below threshold when a weak singleline of a CO2 laser is externally injected into a Q switched CO2 1aser system. For such a regenerative optical amplifier, the input power is amplified by a factor of 106. Without a dispersive element, a single line oscillation is obtained in the range of P(10) to P(32) and R(28) to R(14) of the 10.4 µm band transition for various external signals. The amplification mechanism of the input signal is explained by the assumption that the quantum noise and the external signal are amplified in the same manner, and by the exchange of the noise for the input power. Experimental results agree well with the theoretical results which are derived from the quantum mechanical Langevin equations.