JP2829479B2 - Metal vapor laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor laser which is stimulated to emit by discharge using a vapor of copper or the like contained in a tube, and more particularly to a metal vapor laser excellent in laser conversion efficiency.

[0002]

2. Description of the Related Art At present, in various lasers (light amplification by stimulated emission) used in various fields, vapors of metals such as copper, manganese, lead, gold, calcium, barium, thallium and bismuth are introduced. By performing pulsed discharge inside the tube, the metal vapor laser that stimulates and emits metal atoms with a strong resonance trapping phenomenon is other solid-state lasers,
It has features of higher output and higher energy conversion efficiency than semiconductor lasers, carbon dioxide lasers, and gas lasers except iodine lasers that operate at room temperature.

This metal vapor laser discharges atoms in a metal vapor contained in a tube to bring the atoms into an excited state of resonance transition, and some of the atoms in the excited state emit fluorescent light spontaneously to form a ground. State and metastable state. Then, when the number of atoms in the excited state becomes a population inversion state larger than the number of atoms in the metastable state, the fluorescent light acts on the atoms in the excited state, stimulated emission occurs, and new light is generated. The light is amplified while being reflected between the reflecting mirrors, and a part is output as laser light from the output mirror.

In the case of a copper vapor laser using copper as a laser medium, strong oscillation lines having wavelengths of 510.6 nanometers and 578.2 nanometers exist in a visible light wavelength region, and 1 to 1.2%. With high energy conversion efficiency
High output of several watts to several hundred watts or more has been obtained. For this reason, it is used as an excitation light source for dye lasers to separate uranium isotopes, etc.
Application research is being pursued in a wide range of fields such as industrial use.

[0005]

However, in this metal vapor laser, the metal atoms in the excited state (upper laser level) transition to the ground state and the metastable state energy levels by fluorescence emission. However, in the laser transition, the energy is distributed to the lower level of the laser which is a metastable level having a higher energy level than the ground state. While the excitation lifetime at the upper laser level is several hundred nanoseconds, the transition from the lower laser level to the ground state is a forbidden transition, and the excitation lifetime at the lower laser level is several microseconds. Since the reversal distribution state ends immediately with laser oscillation because it is extremely large from seconds to several tens of microseconds, the conventional metal vapor laser has a self-termination that the output pulse width ends at most several nanoseconds to several tens of nanoseconds It became a mold operation, and its use in many fields was limited.

As a matter of course, if the excitation lifetime at the lower level of the laser is shortened, the population inversion time is increased and the laser output pulse width can be increased, which not only increases the laser conversion efficiency but also increases the laser conversion efficiency. In addition, the possibility of continuous oscillation operation is increased, and the practicality of the metal vapor laser is increased, and effective use in various fields is enabled.

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal vapor laser capable of shortening the excitation lifetime of a lower laser level in a laser transition and increasing the energy conversion efficiency and the possibility of continuous oscillation in laser operation. I do.

[0008]

In order to achieve the above-mentioned object, a metal vapor laser according to the present invention is characterized in that a metal vapor is introduced into a tube as a laser medium, and the metal atoms are excited by a discharge to generate a laser upper level. (Resonance excitation level) In a metal vapor laser excited by stimulated emission at a resonance level, an energy value of a ground state and an energy value of a lower laser level which is a metastable state after a laser transition or a fluorescence transition are contained in the laser medium. The difference between the energy value of the upper laser level and the energy value of the lower laser level of the metal atom is added to the vapor of another metal atom, the metal atom of the lower laser level And the metal atoms of the laser lower level transition to the excited state by energy transfer due to the second type collision with the other metal atom of the laser lower level,
The invention is characterized in that the retention time of the population inversion state, in which the number of atoms in the excited state is larger than the number of atoms in the ground state in the metal atom, is lengthened.

Further, in a metal vapor laser in which a metal vapor is put into a tube as a laser medium, and the metal atoms are excited by a discharge to a laser upper level (resonance excitation level) in an excited state and stimulated emission is performed. In the medium, the difference between the energy value of the upper laser level and the energy value of the lower laser level, which is a metastable state after a laser transition or fluorescence transition, is determined by the energy value of the ground state and the lower laser level of the metal atom. The difference between the energy value of the ground state and the energy value of the laser lower level which is a metastable state after the laser transition or the fluorescence transition is substantially equal to the difference between the energy value of the metal atom and the energy value of the metal atom. A vapor of another metal atom which is substantially equal to the difference between the energy value of the laser level and the energy value of the laser lower level is added, and the gold of the laser lower level is added. The metal atoms in the lower level of the laser are transitioned to a ground state and an excited state by energy transfer due to the second type collision between the atom and the other metal atom in the lower level of the laser. This is also characterized in that the retention time of the population inversion state in which the number of atoms in the excited state increases is lengthened.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a metal vapor laser apparatus according to the present invention, wherein 1 is a laser tube made of ceramics or the like, 2 is a metal or metal compound A serving as a laser medium and a metal or metal compound. Heaters for winding and heating the outer periphery of the laser tube 1 to evaporate B; electrodes 3, 3 located near both ends of the laser tube 1;
Is a transflective output mirror, and 6 is a power supply.

Then, the metal or metal compound A or B put in the laser tube 1 is heated by the heater 2 into vapor, and pulse discharge is performed between the electrodes 3 and 3 by the power supply 6 in the vapor. This causes the metal atom A to be in an excited state, and a part of the metal atom A in this excited state spontaneously emits fluorescence and transitions to a ground state and a metastable state. And metal atom A
When the number of distributions of the excited state in the above becomes an inverted distribution state larger than the number of distributions of the metastable state, the fluorescent light acts on the metal atom A in the excited state to cause stimulated emission to generate new light, which is generated by the reflecting mirror 4. , 5 are amplified while being reflected, and a part is output as laser light from the output mirror 5.

FIG. 2 shows an energy level diagram of the metal vapor laser according to the present invention. The left side shows the energy level of metal A, and the right side shows the energy level of metal B to be added. E
₀ (A) and E ₀ (B) represent ground state energy values in which the metal atoms A and B are not excited, and E ₁ (A) and E ₁ (E)
₁ (B) represents the energy value of the upper level (resonance excitation level) of a laser or fluorescence transition in which metal atoms A and B are excited by collision of electrons due to discharge between electrodes 3 and 3, and E ₂
(A) represents the energy value of the lower laser level which is distributed in a metastable state due to the stimulated emission of the metal atom A at the upper level of the laser, and E ₂ (B) represents the energy level of the metal atom B at the resonance excitation level. It represents the energy value of a metastable level distributed in a metastable state by light emission (or stimulated emission).

ΔE (A) is the value of E in metal atom A
The energy value difference between ₁ (A) and E ₂ (A) represents the energy value required to excite the metal atom A at the lower level of the laser to the upper level of the laser. ΔE (B)
Is the difference between the energy values of E ₁ (B) and E ₂ (B) in metal atom B, which excites metal atom B at the lower level of fluorescence or laser transition to the upper level of fluorescence or laser transition. It represents the energy value required to perform

The metal atoms A stored in the metastable state which is the lower level of the laser and the metal atoms B stored in the metastable state of the fluorescence or the laser transition are E ₂ (A) and E ₂ (A), respectively.
Work corresponding to the energy value of ₂ (B) can be performed, and energy can be efficiently consumed for a work amount substantially equal to this energy value.

[0015] Therefore, the first embodiment related to the present invention and
Therefore, when selecting the additional metal atom B, the fluorescent or
Together with the metal atom B of the metastable level
Energy value ΔE required to excite to ring excitation level
(B) is the energy value of the laser lower level of metal atom A
E ₂ There is one that selects something that is almost equivalent to (A)
You.

As described above, the metal atom A as the laser medium
When metal atom B is added to metal atom A, metal atom A emits laser light.
When the laser emits and transitions to the lower level of the laser,
Stay E ₂ Laser while maintaining the energy value of (A)
-Performs a thermal motion determined by the temperature in the pipe (several hundred degrees Celsius to several hundred degrees Celsius).
Repeats violent collisions with surrounding particles. Also, metal
E of child B ₂ The particles in the (B) state behave similarly.
You. And E ₂ (A) Metal atoms A and E in state
₂ When the metal atom B in the (B) state collides, the metal atom A becomes
The metal atom B is excited by the resonance excitation level E ₁ (B) Exciting work
Then, the metal atom A itself loses energy (deactivates).
Level E ₀ Transition to (A). Also, about this reverse process
Is E ₂ (A) and ΔE (B) are laser transition energy
If the difference is sufficiently different from the energy value, the probability can be ignored.
it can. As a result, the excitation lifetime at the lower level of the laser
As the time becomes shorter, the number of particles of metal atom A in the lower level of the laser
Increase in the number of particles at the lower level of the laser.
Retention time of population inversion where the number of particles in the upper level increases
The laser output pulse width
Therefore, the laser conversion efficiency is increased.

When metal atom A is manganese (Mn)
ΔE (B) ≒ E ₂ (A) additional metal atom
As B, europium (Eu), barium (B
a), lanthanum (La), molybdenum (Mo), niobium
(Nb), platinum (Pt), rhenium (Re), ruthenium
(Ru), titanium (Ti), thulium (Tm), etc.
Exist.

When the metal atom A is copper (Cu)
ΔE (B) ≒ E ₂ (A) additional metal atom
As B, europium (Eu), lanthanum (L
a) d Of (Nb), titanium (Ti), zirconium
(Zr), rhenium (Re), thorium (Th), tan
Gusten (W) and the like exist.

When the metal atom A is arsenic (As),
In this case, ΔE (B) ≒ E ₂ (A) additional metal source
As the child B, chromium (Cr), europium (E
u), iridium (Ir), lantern (La), manga
(Mn), platinum (Pt), rhenium (Re), scan
Indium (Sc), Tantalum (Ta), Thorium (T
h), zirconium (Zr) and the like.

Further, when the metal atom A is gold (Au)
ΔE (B) ≒ E ₂ (A) additional metal atom
As B, gadolinium (Gd), germanium (G
e), hafnium (Hf), iridium (Ir), moly
Buden (Mo), rhodium (Rh), tantalum (T
a), thorium (Th), zirconium (Zr), etc.
Exist.

The metal atom A is replaced with barium (Ba).
ΔE (B) ≒ E ₂ Addition to become (A)
As the metal atom B, europium (Eu), hafnium
(Hf), niobium (Nb), thorium (Th), titanium
(Ti), zirconium (Zr) and the like.

Naturally, other than the above metal atoms,
ΔE (B) ≒ E ₂ Metal atoms A and B satisfying (A)
It is only necessary.

Next, as a second embodiment of the present invention, when selecting an additional metal atom B, a metastable metal atom B
Whose energy value E ₂ (B) is substantially equal to the energy value ΔE (A) required to excite the metal atom A at the lower level of the laser to the resonance excitation level E ₁ (A). To choose.

As described above, the metal atom A as the laser medium
When the metal atom B is added to the metal atom A, the metal atom A in the E ₂ (A) state collides with the metal atom B in the E ₂ (B) state, and the metal atom B displaces the metal atom A to the resonance excitation level E ₁ (A ), The metal atom B loses energy (deactivates) and transitions to the ground level E ₀ (B). As a result, the excitation lifetime in the lower laser level is shortened, the increase in the number of particles of the metal atom A in the lower laser level is suppressed, and the increase in the number of particles in the upper laser level is promoted. The inversion distribution state in which the number of particles in the upper level of the laser is larger than the number is lengthened, that is, the laser output pulse width is increased and the laser conversion efficiency is increased.

When the metal atom A is copper (Cu), E
₂ (B) Examples of the additional metal atom B that satisfies ≒ ΔE (A) include europium (Eu), iron (Fe), osmium (Os), rhenium (Re), tungsten (W), yttrium (Y), Manganese (Mn) is present.

When the metal atom A is manganese (Mn), the additional metal atom B that satisfies E ₂ (B) ≒ ΔE (A) includes arsenic (As) and antimony (Sb).
Etc. exist.

Further, when the metal atom A is barium (Ba), tin (Sn), manganese (Mn), or the like is used as the additional metal atom B such that E ₂ (B) ≒ ΔE (A). Exists.

When the metal atom A is lead (Pb), the additional metal atom B that satisfies E ₂ (B) ≒ ΔE (A) includes europium (Eu) and iridium (I
r) and the like.

When the metal atom A is thallium (Tl), the additional metal atom B that satisfies E ₂ (B) ≒ ΔE (A) includes arsenic (As) and molybdenum (M
o), titanium (Ti) and the like.

Naturally, other than the above metal atoms, any metal atoms A and B that satisfy E ₂ (B) ≒ ΔE (A) may be used.

Next, as a third embodiment of the present invention, when selecting an additional metal atom B, a metal atom B having a metastable level
Energy value ΔE required to excite light to the resonance excitation level
(B) is substantially equal to the energy value E ₂ (A) of the metal atom A at the lower laser level, and the energy value E ₂ (B) of the metal atom B at the metastable level is lower than the laser level. Is selected so that the energy value ΔE (A) required to excite the metal atom A of the above to the resonance excitation level is substantially equal. That is, ΔE (B) ≒ E ₂ (A) and E ₂ (B)
A metal atom that satisfies both ≒ ΔE (A) is selected.

As described above, the metal atom A as the laser medium
Similarly, a metal atom B which is a laser medium is added to E ₂
Metal atom A in state (A) and metal atom B in state E ₂ (B)
Collide, the metal atom A performs the work of exciting the metal atom B to the resonance excitation level E ₁ (B), and the metal atom A loses energy (deactivates) and transitions to the ground level E ₀ (A). At the same time, the metal atom B replaces the metal atom A with the resonance excitation level E
_The metal atom B loses energy (deactivates) and transitions to the ground level E ₀ (B) by performing the work of exciting ₁ (A). As a result, the excitation lifetime of the metal atoms A and B at the lower laser level is shortened, and the increase in the number of metal atoms A and B at the lower laser level is suppressed. The number of particles increases and the number of particles in the upper level of the laser is larger than the number of particles in the lower level of the laser. The conversion efficiency increases.

In each of the above-described embodiments, it is necessary that the energy level associated with the metal atom B to be added does not have an interaction that hinders the laser oscillation operation of the metal atom A as the laser medium. . Also, metal atoms A,
The ratio of the vapor pressure of B is appropriately set so as to extend the inversion distribution holding time, but may be about 1: 1.

The apparatus of the metal vapor laser shown in FIG. 1 is only a schematic one. When the vaporization temperature of the metal or metal compound A or B is different, a dedicated heater is provided for each metal atom. Then, the vapor pressure is controlled for each metal atom.

[0035]

As described above in detail, according to the metal vapor laser of the present invention, the metal atom serving as the laser medium is added with the vapor of another metal atom capable of transferring energy by the second type collision. The excitation lifetime at the lower level of the laser in the laser transition is shortened, the inversion distribution time is increased, and the laser output pulse width can be increased, which not only increases the laser conversion efficiency but also enables continuous oscillation operation Thus, the practicality of the metal vapor laser is increased, and effective use in various fields is possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a metal vapor laser device of the present invention.

FIG. 2 is an energy level diagram of the metal vapor laser of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 2 Heater 3 Electrode 4 Total reflection mirror 5 Output mirror 6 Supply power

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01S 3/227

Claims (2)

(57) [Claims] 1. A metal vapor laser in which a metal vapor is introduced into a tube as a laser medium, and the metal atoms are excited to a laser upper level (resonance excitation level) in an excited state by discharge and stimulated-emitted. In the medium, the difference between the energy value of the ground state and the energy value of the lower level, which is a metastable state after the laser transition or the fluorescence transition, is determined by the energy value of the upper laser level and the lower laser level of the metal atom. And adding a vapor of another metal atom which is substantially equivalent to the energy value of the second metal atom in the lower level of the laser and the other metal atom of the lower level in a metastable state.
The metal atoms in the lower level of the laser are transitioned to the upper level of the laser by energy transfer due to seed collision, and the number of atoms in the upper level of the laser is larger than the number of atoms in the lower level of the laser in the metal atom. A metal vapor laser characterized by a longer holding time. 2. A metal vapor laser in which a metal vapor is introduced into a tube as a laser medium, and the metal atoms are excited by a discharge to a laser upper level (resonance excitation level) in an excited state and stimulated emission is performed. In the medium, the difference between the energy value of the upper laser level and the energy value of the lower laser level, which is a metastable state after laser transition, is the energy value of the ground state and the lower energy level of the metal atom in the metal atom. And the difference between the energy value of the ground state and the energy value of the lower laser level which is a metastable state after the laser transition is the same as the energy value of the upper laser level and the lower laser level of the metal atom. A vapor of another metal atom which is substantially equivalent to the difference between the energy value of the level and the metal atom of the lower laser level and the other metal source of the lower laser level are added. The metal atoms at the lower level of the laser and the other metal atoms transition to the ground state and the upper level of the laser, respectively, by the energy transfer due to the second kind collision with the atoms, and the number of atoms of the lower level of the laser in both metal atoms A metal vapor laser characterized by having a longer inversion distribution holding time in which the number of atoms in the upper level of the laser is larger than that of the laser.