Method and apparatus for generating high-power terahertz wave
View Patent ↗A method and apparatus for generating terahertz waves using laser plasma are disclosed herein. The method of generating high-power terahertz waves includes generating plasma by focusing a laser beam on a gas within a vacuum chamber, radiating laser beams into the magnetized plasma from opposite directions so that the laser beams collide with each other at a preset location, and generating terahertz waves of a predetermined frequency through the oscillation of the plasma generated by the collision of the laser beams.
1. A method of generating high-power terahertz waves, comprising:
generating plasma by focusing a laser beam on a gas within a vacuum chamber;
magnetizing the generated plasma by a magnetic field generator;
radiating laser beams into the magnetized plasma from opposite directions so that the laser beams collide with each other at a preset location; and
generating terahertz waves of a predetermined frequency through oscillation of the plasma generated by the collision of the laser beams.
2. The method of claim 1 , wherein the preset location is a periphery of the plasma generated within the vacuum chamber.
3. The method of claim 1 , wherein the laser beams radiated into the magnetized plasma comprises two laser beams that have a preset or lower level of power and are controlled such that they are directed toward a periphery of the plasma from opposite directions and thus collide with each other.
4. The method of claim 3 , wherein, when the laser beams having the preset or lower level of power collide with each other in the magnetized plasma, a critical or higher level of plasma waves are formed, and a current in the plasma waves generates terahertz waves while oscillating at a plasma frequency.
5. The method of claim 4 , wherein the terahertz waves are generated through formation of the current, which is stationary and oscillates at the plasma frequency, by the formed plasma, as given by the following equation:
eE
THz
mc
ω
=
π
16
ω
c
ω
p
σ
2
k
2
α
0
4
ⅇ
-
0.084
ω
p
2
τ
2
where σ is a length of laser pulses/2, k is a number of laser waves, α 0 is a normalized vector potential of the laser beams, τ is laser beam duration/2, ω p is the plasma frequency, ω c is eB/m, and E THz is magnitude of the terahertz electric field.
6. The method of claim 4 , wherein the magnitude of the electric field inside the plasma is expressed by the following equation:
e
E
^
(
x
,
t
)
mc
ω
p
≃
-
σ
_
J
j
0
2
t
_
3
/
2
x
_
2
cos
(
x
_
2
2
t
_
+
π
4
)
σ
_
J
=
ω
p
σ
J
/
c
j
0
=
J
0
/
en
0
c
t
_
=
ω
p
t
where J 0 is a current density deduced from the following equation:
eE
THz
mc
ω
=
π
16
ω
c
ω
p
σ
2
k
2
α
0
4
ⅇ
-
0.084
ω
p
2
τ
2
where σ is a length of laser pulses/2, k is a number of laser waves, α 0 is a normalized vector potential of the laser beams, τ is laser beam duration/2, ω p is the plasma frequency, ω c is eB/m, and E THz is magnitude of the terahertz electric field.
7. An apparatus for generating high-power terahertz waves, comprising:
a vacuum chamber;
a gas regulator configured to supply a gas to the vacuum chamber;
a laser generator configured to generate laser beams having a preset level of energy and a preset or lower level of power, and to radiate two laser beams toward a periphery of plasma within the vacuum chamber from opposite directions so that the two laser beams collide with each other;
a plasma generator configured to generate plasma in response to a laser beam radiated into the vacuum chamber and focused on the gas; and
a magnetic field generator configured to magnetize the plasma generated by the plasma generator, and to generate terahertz waves of a predetermined frequency using oscillation of the plasma generated through the collision of the opposite laser beams by the laser generator.