DE1283413B - Optical transmitter or amplifier with nitrogen as a stimulable medium for coherent radiation - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

HOIs

German class: 21g-53/12

Number:
File number:
Registration date:
Display day:

P 12 83 413.8-33 (O 792)

4th August 1964

November 21, 1968

The invention relates to an optical transmitter or amplifier with nitrogen as a stimulable medium for coherent radiation in the short-wave, preferably in the ultraviolet spectral range.

Is known an optical transmitter or amplifier in the UV range that with pure nitrogen and with certain discharge conditions, preferably wavelengths of the second positive group of nitrogen molecules, emitted. This transmitter works on the type of two-level laser, and here is only one Impulse operation possible. However, continuous operation is particularly desirable in the case of gas lasers. aside from that The well-known nitrogen laser requires extremely high field strengths for excitation.

In order to achieve an effective reversal of the normal population distribution for the triplet terms of the nitrogen molecule in question with relatively simple technical effort, it is proposed to excite the C ³ 5r _u terms of the nitrogen molecule after energy transfer through collisions of the second kind between the metastable levels of the To bring about noble gas atoms and nitrogen molecules. For this purpose, a discharge in noble gas-nitrogen mixtures can be used, the noble gas pressure being in the range from 10 to 500 Torr and the nitrogen content not being significantly more than 1%.

The excitation mechanism effective in such mixtures can be described as follows are: Because in the noble gas-nitrogen mixture the nitrogen molecules are only in very low concentration is the probability of collisions between the free electrons and nitrogen molecules tiny. In contrast, the free electrons preferentially collide with the noble gas atoms, elastic until the kinetic energy of the electrons is sufficient to generate the to stimulate the lowest noble gas levels. The noble gas atoms excited in this way then transfer their Excitation energy preferentially through collisions of the second kind on the nitrogen molecules when the noble gas pressures and the vessel dimensions are chosen so that inelastic collisions with the wall are less common than with nitrogen molecules. For this, noble gas pressures between 10 and 500 Torr are suggested, each according to the cross section of the discharge tube and the electrical discharge parameters. It must be avoided be that the excited noble gas atoms due to collisions with the vessel walls radiationless in the Skip the basic state.

Very fast electrons can hardly excite triplet terms of the nitrogen molecules directly. Optical transmitter or amplifier with nitrogen
as a stimulable medium
for coherent radiation

Applicant:

Original Hanau Quarzlampen-Gesellschaft mbH, 6450 Hanau

Named as inventor:

Dr. Wolfgang Friedl, 6450 Hanau;

Dr. Volker Schäfer, 6451 Bruchköbel

because this would require a flip of an electron spin, for which a minimum time of Interaction during collision would be required, which is not the case with fast electrons. By slow Electrons in pure nitrogen the direct excitation of the triplet terms is so noticeable that it is practical no inversion of the normal population distribution for the triplet system can be obtained. A noticeable reversal of the population distribution of the triplet system therefore takes place in pure nitrogen practically only at very high field strengths or at low pressures and large pipe cross-sections Energy transfer from the singlet system.

In noble gas-nitrogen mixtures, on the other hand, relatively high pressures and relatively small cross-sections can be used and also smaller field strengths are worked to reverse the normal occupation distribution to achieve.

_{The S 5} ( ³ P ") and the s ₃ ( ³ P") levels of the noble gases in question are essentially suitable for the energy transfer. Their excitation energies are

Argon:

S ₅ 11.55 eV 4, N ₂ :

Second vibration level
of C ³ Jr ₁₁ at 11.5 eV

S ₃ 11.73 eV ^ N ₂ :

Third vibration level

of C ³ JTu at 11.7 eV
Krypton:

s _s 9.91 eV ^ N ₂ :

Fourteenth level of vibration

of Β ³ π _κ at 10 eV
Xenon:

S ₅ 8.31 eV ^ N ₂ :

Fifth vibration level

of Β ³ π _Β at 8.3 eV

809 638/1345

The following transitions come from the vibration levels excited by argon and xenon in question:

Argon:

Second vibration level:

(2-0): 297.7 nm

(2-1): 313.5 nm

(2-2): 330.9 nm

(2-3): 350.0 nm

(2-4): 371.0 nm

(2-5): 394.2 nm

: _u Third vibration level:

(3-0): 282.0 nm _1S

(3-1): 296.2 nm

(3-2): 311.6 nm

(3-3): 328.5 nm

(3-5): 367.1 nm

(3-6): 389.4 nm _ao

The numbers in brackets mean the vibration quantum numbers of the initial and final state of the transition in question.

Xenon:

B ³ TTg Fifth vibration level:

(5-1): 612.6 nm (5-2): 670.3 nm

In order to obtain short wavelengths, argon must therefore preferably be used. Used as an inert gas If helium is used, the output levels are preferred through an analog energy transfer process occupied by the so-called negative nitrogen bands. Bands are then broadcast according to the Transitions between the two electron levels may be either short-wave or to obtain long-wave bands in continuous operation.

All common discharges are suitable for excitation. The discharge should be in tubes with a Diameters of 1 to 30 mm take place at around 10 to 500 Torr. Smaller diameters are larger Press to choose.

Claims (2)

Patent claims: 1. Optical transmitter or amplifier with nitrogen as a stimulable medium for coherent Radiation, characterized in that it is predominantly used for generating ultraviolet Radiation is added to the nitrogen noble gas, the noble gas pressure in the range from 10 to 500 Torr and the nitrogen content is not significantly more than 1%. 2. Optical transmitter or amplifier according to claim 1, characterized in that the noble gas Is helium. 3. Optical transmitter or amplifier according to claim 1, characterized in that the noble gas Is argon. 4. Optical transmitter or amplifier according to claim 1, characterized in that the noble gas Krypton is. 5. Optical transmitter or amplifier according to claim 1, characterized in that the noble gas Xenon is. 6. Optical transmitter or amplifier according to claims 1 and 3, characterized in that the argon levels S ₅ ( ³ P?) And / or So ( ³ PS) are used for the selective excitation of the nitrogen molecule. and References Considered: These range essentially between 380 and Journal of Applied Physics, Vol. 35, No. 1, January 510 nm. 1964, pp. 252 to 254; By variation of the proposed noble gases 40 Physical Review, Vol. 133, No. 5A, March 2, 1964, Helium, argon, krypton and xenon are advantageous. See A1244 / 48. 209 638/1345 11.68 Q Bundesdruckerei Berlin