Terahertz wave generator and method of generating terahertz wave

1. A terahertz wave generator comprising:

a first light source outputting a first light having a first frequency;

a second light source outputting a second light having a second frequency different from the first frequency;

a second harmonic generation unit performing second harmonic conversion on the first and second lights to generate a third light and a fourth light; and

a photomixer converting a mixing light of the third and fourth lights into a terahertz wave alternating signal and outputting a terahertz wave.

2. The terahertz wave generator of claim 1 , wherein the second harmonic generation unit adjusts incidence angles of the third and fourth lights such that the third and fourth lights are mixed and a result is incident onto the photomixer.

3. The terahertz wave generator of claim 1 , wherein the third light has a frequency two times higher than a frequency of the first light and the fourth light has a frequency two times higher than a frequency of the second light.

4. The terahertz wave generator of claim 1 , wherein the photomixer generates an alternating signal having a frequency corresponding to a difference between frequencies of the third and fourth lights.

5. The terahertz wave generator of claim 1 , wherein each of the first and second light sources is an InP-based light source generating light having a band of 1300 nm to 1550 nm.

6. The terahertz wave generator of claim 1 , wherein each of the first and second light sources has a wavelength lower than a bandgap energy of an InP or GaAs-based photomixer.

7. The terahertz wave generator of claim 1 , wherein the photomixer is an GaAs-based photomixer having an operating band of 800 nm to 900 nm.

8. The terahertz wave generator of claim 1 , wherein one of the first and second light sources is a variable frequency light source.

9. The terahertz wave generator of claim 8 , wherein the alternating signal output from the photomixer is varied twice more than a frequency variation of the first or second light source.

10. A terahertz wave generator comprising:

a dual-mode single resonator generating two lights having different frequencies and outputting a first light having a frequency corresponding to a difference between frequencies of the two lights;

a second harmonic generator performing second harmonic conversion on the first light to output a second light; and

a photomixer converting the second light into a terahertz wave alternating signal and outputting a terahertz wave.

11. The terahertz wave generator of claim 10 , wherein a frequency of the second light is double of a frequency of the first light.

12. A terahertz wave generating method comprising:

generating a first light and a second light having different frequencies;

generating a third light by performing second harmonic generation on the first and second lights and mixing the first and second lights;

converting the third light into a terahertz wave alternating signal using a photomixer; and

outputting the terahertz wave alternating signal as a terahertz wave.