JP4676280B2 - Light generation device and terahertz light generation device including the device - Google Patents

Description

  The present invention relates to generation of light of two types of wavelengths by optical parametric oscillation.

  Conventionally, light is obtained by irradiating a KTP crystal with an excitation laser to perform optical parametric conversion. Here, two KTP crystals are used, the first KTP crystal irradiated with the excitation laser is fixed, the second KTP crystal is rotated, and tilted with respect to the first KTP crystal. Light with a wavelength can be obtained (see, for example, Patent Document 1). Note that the wavelength of light obtained from the second KTP crystal can be changed by changing the angle of the second KTP crystal with respect to the first KTP crystal.

  However, since the second KTP crystal is inclined with respect to the first KTP crystal, the excitation laser and the beam path of light obtained from the first KTP crystal are refracted by the second KTP crystal. As a result, when the angle of the second KTP crystal with respect to the first KTP crystal is changed, the beam path of the light obtained from the first and second KTP crystals fluctuates later than the second KTP crystal. Become.

  Here, if the light obtained from the first KTP crystal and the light obtained from the second KTP crystal are reflected back to the second KTP crystal, the first KTP of the second KTP crystal Even if the angle with respect to the crystal is changed, the beam path of the light obtained from the first and second KTP crystals does not change after passing through the second KTP crystal (see, for example, Non-Patent Document 1).

JP 2004-219967 A T.Taniuchi, H.Adachi, S.Okada, T.Sasaki and H.Nakanishi, “Continuously tunable THz and far-infrared wave generation from DAST crystal”, Electronics Letters, vol.40, no.9, pp.549- 551 (2004)

  However, in order to reflect the light obtained from the first and second KTP crystals back to the second KTP crystal, in addition to the two mirrors for generating optical parametric resonance, the first and second A reflecting mirror for reflecting the light obtained from the second KTP crystal and a half mirror for guiding the excitation laser to the first KTP crystal are required, and a complicated configuration is required.

  Therefore, an object of the present invention is to keep the optical paths of light of two types of wavelengths constant with a simple configuration.

  A light generation apparatus according to the present invention includes an excitation laser light source that generates excitation laser light, a first mirror that has a reflectance that is lower than that of light that has a wavelength different from that of the excitation laser light, First light generating means for generating first light by optical parametric conversion generated by receiving the excitation laser light transmitted through the first mirror, and transmitting the first light, the first mirror and the first light A second light generating means for generating second light by optical parametric conversion generated by receiving the excitation laser light transmitted through the generating means, and partially reflecting the first light and the second light, A second mirror that returns to the second light generation means, an optical path of the first light that passes through the second light generation means and travels toward the second mirror, and from the second light generation means to the second light mirror Wherein the second optical path of the directed is configured to be from the first light generating means on the extension of the optical path of the first light toward the second light generating means.

  According to the light generation device configured as described above, the excitation laser light source generates excitation laser light. The first mirror has a reflectance with respect to the excitation laser light lower than a reflectance with respect to light having a wavelength different from that of the excitation laser light. The first light generation means generates the first light by optical parametric conversion generated by receiving the excitation laser light transmitted through the first mirror. Second light generation means transmits the first light and generates second light by optical parametric conversion generated by receiving the excitation laser light transmitted through the first mirror and the first light generation means. The second mirror partially reflects the first light and the second light and returns them to the second light generating means.

  In addition, the optical path of the first light that passes through the second light generation unit and travels toward the second mirror, and the optical path of the second light that travels from the second light generation unit toward the second mirror include the first light generation unit. It is on an extension of the optical path of the first light from the one light generating means to the second light generating means.

  Further, in the light generation apparatus according to the present invention, the first light generation means is a first nonlinear optical crystal, and the excitation laser light received by the first light generation means is changed without changing the traveling direction thereof. The direction of the first light generation means may be determined so as to transmit the first light generation means.

  In the light generation device according to the present invention, the second light generation unit may transmit the first light traveling from the first light generation unit to the second light generation unit while changing a traveling direction thereof. An orthogonal line orthogonal to the straight line in a plane including a second nonlinear optical crystal whose orientation is determined and a straight line extending in the traveling direction of the excitation laser light from the first mirror toward the first light generation means A second nonlinear optical crystal that is line symmetric with the second nonlinear optical crystal, and the second nonlinear optical crystal and the third nonlinear optical crystal are made of the same material, and The third nonlinear optical crystal and the orthogonal line may be disposed between the first light generation means and the second mirror.

  Further, the light generation device according to the present invention is directed so that the first light generation unit transmits the excitation laser light traveling from the first mirror toward the first light generation unit while changing its traveling direction. The fourth nonlinear optical crystal is determined and an orthogonal line orthogonal to the straight line in a plane including a straight line extending in the traveling direction of the excitation laser light from the first mirror toward the first light generation means, A fourth nonlinear optical crystal that is symmetrical with the fourth nonlinear optical crystal, and the fourth nonlinear optical crystal and the fifth nonlinear optical crystal are made of the same material, and the fourth nonlinear optical crystal and the fifth nonlinear optical crystal The five nonlinear optical crystals and the orthogonal line may be arranged between the first mirror and the second light generation means.

  In the light generation device according to the present invention, the light traveling back and forth between the first mirror and the second mirror may resonate.

  In the light generation device according to the present invention, the second mirror reflects the idler light component of the first light and the idler light component of the second light with a reflectance of 40% or more and 90% or less. May be.

  In the light generation device according to the present invention, the partial reflection mirror may reflect the signal light component of the first light and the signal light component of the second light with a reflectance of 40% to 90%. May be.

  The light generation device according to the present invention includes a first laser light source that generates a first laser beam having the same wavelength as the idler light component of the first light, and a second laser having the same wavelength as the idler light component of the second light. A second laser light source for generating laser light; an optical multiplexer for combining the first laser light and the second laser light; and an output of the optical multiplexer for outputting the first light generation means and the second light You may make it provide the light injection means inject | poured into the optical path of the said excitation laser beam in a light generation means.

  The light generation device according to the present invention includes a first laser light source that generates a first laser light having the same wavelength as the signal light component of the first light, and a second light having the same wavelength as the signal light component of the second light. A second laser light source for generating laser light; an optical multiplexer for combining the first laser light and the second laser light; and an output of the optical multiplexer for outputting the first light generation means and the second light You may make it provide the light injection means inject | poured into the optical path of the said excitation laser beam in a light generation means.

  In the light generation device according to the present invention, the light injecting means transmits the light transmitted through the second mirror, reflects the output of the optical multiplexer, and transmits the light transmitted through the second mirror. The light may travel on the road in the direction opposite to the light transmitted through the second mirror.

  Further, in the light generation device according to the present invention, the light injection means transmits the excitation laser light from the excitation laser light source toward the first light generation means, reflects the output of the optical multiplexer, and You may make it advance on the optical path of excitation laser beam in the same direction as said excitation laser beam.

  The terahertz light generation device according to the present invention is equivalent to the light generation device according to the present invention and a difference in optical frequency between two light components of light transmitted through the second mirror and received by the light transmitted through the second mirror. Difference frequency light generation means for generating difference frequency light having an optical frequency.

  Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a diagram showing a configuration of a light generation apparatus 1 according to a first embodiment of the present invention. The light generation apparatus 1 according to the first embodiment includes an excitation laser light source 10, a first mirror 12, a first nonlinear optical crystal (first light generation unit) 22, and a second nonlinear optical crystal (second light generation unit) 32. A third nonlinear optical crystal (second light generating means) 34 and a second mirror 42.

  The excitation laser light source 10 generates excitation laser light. The excitation laser beam is, for example, the second harmonic (wavelength 532 nm) of an Nd: YAG laser.

  The first mirror 12 is a mirror whose reflectivity with respect to the excitation laser beam (wavelength 532 nm) is lower than the reflectivity with respect to light having a wavelength different from that of the excitation laser beam. In other words, the mirror has a high transmittance with respect to the excitation laser beam (wavelength 532 nm). In addition, it is preferable that it is highly reflective with respect to the light from which a wavelength differs from excitation laser light. The first mirror 12 is arranged at right angles to the optical path of the excitation laser beam, and the excitation laser beam passes straight without being refracted.

The first nonlinear optical crystal (first light generation means) 22 receives the excitation laser light transmitted through the first mirror 12. The first nonlinear optical crystal 22 is a KTP crystal (KTiOP ₄ crystal). However, other types of nonlinear optical crystals (for example, LiIO ₃ , LiNbO ₃ , b-BaB ₂ O _4, etc.) may be used. The type of the first nonlinear optical crystal 22 is determined according to the wavelength of light desired to be generated by the first nonlinear optical crystal 22.

The first nonlinear optical crystal 22 is excited by receiving the excitation laser beam. When excited, an optical parametric transformation occurs. By optical parametric conversion (ω _pump = ω _signal + ω _idler , ω: light angular frequency, ω _pump : light angular frequency of _pump laser light, ω _signal : light angular frequency of signal light, ω _idler : light angular frequency of idler light) Signal light (800-950 nm) and idler light (1200-1600 nm) are generated. Signal light and idler light generated by the first nonlinear optical crystal 22 are referred to as first light. The wavelength of the first light is determined by the crystal angle of the first nonlinear optical crystal 22. Therefore, the wavelength of the first light is determined by the angle of the first nonlinear optical crystal 22 with respect to the optical path of the excitation laser light.

  The direction of the first nonlinear optical crystal 22 is determined so that the excitation laser light received by the first nonlinear optical crystal 22 is transmitted through the first nonlinear optical crystal 22 without changing its traveling direction. In the example shown in FIG. 1, the first nonlinear optical crystal 22 is rectangular, and its short side receives excitation laser light. And the short side is arrange | positioned at right angles to the advancing direction of excitation laser light. Then, since the incident angle is 90 degrees, the excitation laser light travels straight without being refracted. Although the first nonlinear optical crystal 22 has been described as being rectangular, more precisely, the cross section of the first nonlinear optical crystal 22 in FIG. 1 is rectangular. For example, the first nonlinear optical crystal 22 is It is a rectangular parallelepiped. Hereinafter, the portion simply described as a rectangle has the same meaning.

  The second nonlinear optical crystal (second light generation means) 32 and the third nonlinear optical crystal (second light generation means) 34 transmit the first light. In addition, it receives the excitation laser light that has passed through the first mirror 12 and the first nonlinear optical crystal 22. This causes optical parametric conversion. Optical parametric conversion generates signal light (800 to 950 nm) and idler light (1200 to 1600 nm). Signal light and idler light generated by the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are referred to as second light. The second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are made of the same material (in this embodiment, a KTP crystal).

  The second light has a wavelength different from that of the first light because the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). . The angle at which the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are inclined with respect to the optical path P0 is preferably variable. Further, since the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are inclined at the same angle with respect to the optical path P0, the wavelength of light generated by the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are The wavelength of the generated light is equal. Therefore, both are treated as second light. The light generated by the second nonlinear optical crystal 32 is called second light (front component), and the light generated by the third nonlinear optical crystal 34 is called second light (rear component).

  In the example shown in FIG. 1, the second nonlinear optical crystal (second light generating means) 32 is rectangular, and its short side receives excitation laser light. The short side is inclined with respect to the traveling direction of the excitation laser beam.

  The third nonlinear optical crystal (second light generation means) 34 is line-symmetric with the second nonlinear optical crystal (second light generation means) 32 with respect to the orthogonal line S. However, the second nonlinear optical crystal 32, the third nonlinear optical crystal 34, and the orthogonal line S are disposed between the first nonlinear optical crystal 22 and the second mirror 42.

  In addition, the orthogonal line S is a line orthogonal to the straight line on a plane (paper surface in FIG. 1) including a straight line extending in the traveling direction of the excitation laser light from the first mirror 12 toward the first nonlinear optical crystal 22.

  The second mirror 42 partially reflects the first light and the second light and returns them to the third nonlinear optical crystal (second light generating means) 34. For example, the second mirror 42 reflects the idler light component of the first light and the idler light component of the second light with a reflectance of 40% to 90%, and the signal light component of the first light and the second light The signal light component is totally reflected. The second mirror 42 reflects the signal light component of the first light and the signal light component of the second light with a reflectance of 40% or more and 90% or less, and the idler light component of the first light and the second light The idler light component may be totally reflected. Thereby, the light reciprocating between the first mirror 12 and the second mirror 42 causes resonance. The second mirror 42 is disposed at a right angle to the optical path P0 of the excitation laser light.

  Next, the operation of the first embodiment will be described.

  First, the progression of excitation laser light will be described with reference to FIG. The excitation laser light is emitted from the excitation laser light source 10, passes through the first mirror 12, and enters the first nonlinear optical crystal 22. Here, the optical path of the excitation laser light that passes through the first mirror 12 and travels toward the first nonlinear optical crystal 22 is referred to as P0.

  The excitation laser light passes through the first nonlinear optical crystal 22 without changing the traveling direction. Then, the light enters the second nonlinear optical crystal 32. The second nonlinear optical crystal 32 is inclined with respect to the optical path of the incident excitation laser beam, and the excitation laser beam is refracted and shifted downward on the paper surface of FIG. When excitation laser light is emitted from the second nonlinear optical crystal 32, it travels in parallel with the optical path P 0 and enters the third nonlinear optical crystal 34. The excitation laser light is refracted and shifted upward on the paper surface of FIG. Since the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric, they are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). When the laser beam is emitted, it proceeds on the extension line of the optical path P0. As will be described later, the idler light component of the first light and a part of the idler light component of the second light are transmitted as the two-wavelength light L through the second mirror 42.

  FIG. 2 is a diagram illustrating an optical path of the first light. When the first nonlinear optical crystal 22 receives the excitation laser light, first light is generated from the first nonlinear optical crystal (first light generating means) 22. The first light travels on the extension of the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22 (that is, the optical path P3) and is incident on the second nonlinear optical crystal (second light generating means) 32. . The second nonlinear optical crystal 32 is inclined with respect to the optical path of the incident first light, and the first light is refracted (that is, transmitted while changing the traveling direction), and is directed downward on the paper surface of FIG. It will shift. When the first light is emitted from the second nonlinear optical crystal 32, it travels parallel to the optical path P0 and enters the third nonlinear optical crystal 34. The first light is refracted and shifted upward on the paper surface of FIG. Since the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric, they are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). When one light is emitted, the light travels on an extension line of the optical path P0. That is, the optical path P1 of the first light that passes through the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 and travels toward the second mirror 42 is the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22. It is on the extension line.

  FIG. 3 is a diagram illustrating an optical path of the second light (front component). Excitation laser light is incident on the second nonlinear optical crystal 32. The second nonlinear optical crystal 32 is inclined with respect to the optical path of the incident excitation laser beam, and the excitation laser beam is refracted and shifted downward on the paper surface of FIG. Therefore, when the second light (front component) is emitted from the second nonlinear optical crystal 32, the second light (front component) is separated downward from the extension line of the optical path P0 on the paper surface of FIG. The light travels in parallel and enters the third nonlinear optical crystal 34. Since the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric, they are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). When two lights (front component) are emitted, the light travels on an extension line of the optical path P0. That is, the optical path P2 of the second light traveling from the second nonlinear optical crystal 32 to the second mirror 42 is on an extension line of the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22.

  FIG. 4 is a diagram illustrating an optical path of the second light (rear component). Excitation laser light is incident on the third nonlinear optical crystal 34. The third nonlinear optical crystal 34 is inclined with respect to the optical path of the incident excitation laser beam, and the excitation laser beam is refracted and shifted upward on the paper surface of FIG. Moreover, the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric and are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). Therefore, when the second light (rear component) is emitted from the third nonlinear optical crystal 34, the second light (rear component) travels on the extension line of the optical path P0. That is, the optical path P2 of the second light traveling from the third nonlinear optical crystal 34 to the second mirror 42 is on an extension line of the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22.

  Therefore, the first light and the second light traveling from the third nonlinear optical crystal 34 toward the second mirror 42 are overlapped on the extension line of the optical path P0 (the optical path P1 and the optical path P2). Since there is an optical path P3 (the optical path of the first light from the first nonlinear optical crystal 22 to the second nonlinear optical crystal 32 (see FIG. 2)) on the extended line of the optical path P0, the second nonlinear optical crystal 34 to the second optical path P0. It can be said that the first light and the second light traveling toward the mirror 42 overlap on the extension line of the optical path P3.

  The second mirror 42 partially reflects the first light and the second light. As a result, the first light and the second light are transmitted through the third nonlinear optical crystal 34, the second nonlinear optical crystal 32, and the first nonlinear optical crystal 22, and all pass through the optical path P0 toward the first mirror 12. The first mirror 12 reflects the first light and the second light. The first light and the second light are directed to the second mirror 42. Thereby, the 1st light and 2nd light which reciprocate between the 1st mirror 12 and the 2nd mirror 42 raise | generate resonance. The first light and the second light that have caused resonance pass through the second mirror 42 as the two-wavelength light L. The two-wavelength light L has an idler light component of the first light and an idler light component of the second light, or has a signal light component of the first light and a signal light component of the second light.

  According to the first embodiment, the optical path of light of two types of wavelengths (first light and second light) can be kept constant with a simple configuration in which the third nonlinear optical crystal 34 is further provided. That is, even if the inclination angle of the second nonlinear optical crystal 32 with respect to the optical path P0 is changed, the two-wavelength light L always travels on the extended lines of the optical path P0 and the optical path P3.

  FIG. 13 is a diagram illustrating the optical paths of the first light and the second light in the comparative example in the case where the third nonlinear optical crystal 34 is not provided. FIG. 13A is a diagram illustrating the optical paths of the first light and the second light when the inclination of the second nonlinear optical crystal 32 with respect to the optical path P0 is small. The optical paths of the first light and the second light are shifted downward by Y1 from the extended line of the optical path P0. FIG. 13B is a diagram illustrating the optical paths of the first light and the second light when the inclination of the second nonlinear optical crystal 32 with respect to the optical path P0 is large. The optical path of the first light and the second light is shifted downward by Y2 from the extension line of the optical path P0. Here, Y1 <Y2. That is, the optical path of the first light and the second light after the second nonlinear optical crystal 32 varies. However, according to the first embodiment, it does not vary as described above.

Second Embodiment In the second embodiment, instead of the first nonlinear optical crystal 22, a fourth nonlinear optical crystal (first light generating means) 24 and a fifth nonlinear optical crystal (first light generating means) 26 are provided. The point provided is different from the first embodiment.

  FIG. 5 is a diagram showing a configuration of the light generation apparatus 1 according to the second embodiment of the present invention. The light generation apparatus 1 according to the second embodiment includes an excitation laser light source 10, a first mirror 12, a fourth nonlinear optical crystal (first light generation unit) 24, and a fifth nonlinear optical crystal (first light generation unit) 26. , A second nonlinear optical crystal (second light generating means) 32, a third nonlinear optical crystal (second light generating means) 34, and a second mirror 42. Hereinafter, the same parts as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The excitation laser light source 10, the first mirror 12, the second nonlinear optical crystal (second light generation means) 32, the third nonlinear optical crystal (second light generation means) 34, and the second mirror 42 are the same as those in the first embodiment. It is the same and description is omitted.

  The fourth nonlinear optical crystal (first light generating means) 24 and the fifth nonlinear optical crystal (first light generating means) 26 receive the excitation laser light. This causes optical parametric conversion. Optical parametric conversion generates signal light (800 to 950 nm) and idler light (1200 to 1600 nm). Signal light and idler light generated by the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are referred to as first light. The fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are made of the same material (in this embodiment, a KTP crystal).

  Since the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different), the wavelength of the light generated by the fourth nonlinear optical crystal 24 is different. And the wavelength of the light generated by the fifth nonlinear optical crystal 26 is equal. Therefore, both are treated as the first light. The light generated by the fourth nonlinear optical crystal 24 is referred to as first light (front component), and the light generated by the fifth nonlinear optical crystal 26 is referred to as first light (rear component). The angle at which the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are inclined with respect to the optical path P0 is preferably variable.

  In the example shown in FIG. 5, the fourth nonlinear optical crystal 24 is rectangular, and its short side receives excitation laser light. The short side is inclined with respect to the traveling direction of the excitation laser beam.

  The fifth nonlinear optical crystal 26 is line symmetric with the fourth nonlinear optical crystal 24 with respect to the orthogonal line S1. However, the fourth nonlinear optical crystal 24, the fifth nonlinear optical crystal 26, and the orthogonal line S1 are disposed between the first mirror 12 and the second nonlinear optical crystal (second light generating means) 32.

  Further, the orthogonal line S1 is a straight line on a plane (paper surface in FIG. 5) including a straight line extending in the traveling direction of the excitation laser light from the first mirror 12 toward the fourth nonlinear optical crystal (first light generating means) 24. It is a line orthogonal to. The orthogonal line S2 is the same as the orthogonal line S (see FIG. 1).

  The fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are made of the same material (in this embodiment, a KTP crystal).

  Next, the operation of the second embodiment will be described.

  First, the progression of excitation laser light will be described with reference to FIG. The excitation laser light is emitted from the excitation laser light source 10, passes through the first mirror 12, and enters the fourth nonlinear optical crystal 24. Here, the optical path of the excitation laser light that passes through the first mirror 12 and travels toward the fourth nonlinear optical crystal 24 is referred to as P0.

  The fourth nonlinear optical crystal 24 is tilted with respect to the optical path of the incident excitation laser light, and the excitation laser light is refracted (that is, transmitted while changing the traveling direction) and is directed downward on the paper surface of FIG. It will shift. When excitation laser light is emitted from the fourth nonlinear optical crystal 24, it travels parallel to the optical path P0 and is incident on the fifth nonlinear optical crystal 26. The excitation laser light is refracted and shifted upward on the paper surface of FIG. Since the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are line symmetric, they are tilted at the same angle with respect to the optical path P0 (however, the tilt directions are different), and thus excited from the fifth nonlinear optical crystal 26. When the laser beam is emitted, it proceeds on the extension line of the optical path P0.

  Then, the excitation laser light is incident on the second nonlinear optical crystal 32. The subsequent steps are the same as those in the first embodiment, and the description thereof is omitted (see FIG. 1).

  FIG. 6 is a diagram illustrating an optical path of the first light (front component). The excitation laser light transmitted through the first mirror 12 is incident on the fourth nonlinear optical crystal (first light generating means) 24. The fourth nonlinear optical crystal 24 is inclined with respect to the optical path P0 of the incident excitation laser light, and the excitation laser light is refracted (that is, transmitted while changing the traveling direction) and is directed downward on the paper surface of FIG. It will shift to. Therefore, when the first light (front component) is emitted from the fourth nonlinear optical crystal 24, the first light (front component) is separated downward from the extension line of the optical path P0 in the plane of FIG. The light travels in parallel and enters the fifth nonlinear optical crystal 26. Since the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are line symmetric, they are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). When one light (front component) is emitted, the light travels on an extension line of the optical path P0 (that is, the optical path P3). The subsequent steps are the same as in the first embodiment, and the description thereof is omitted (see FIG. 2). As in the first embodiment, the optical path P1 of the first light (front component) that passes through the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 and travels toward the second mirror 42 is the fourth nonlinear optical crystal ( The first light generating means) 24 is on an extension of the optical path P0 of the excitation laser light received by the first light generating means) 24.

  FIG. 7 is a diagram illustrating an optical path of the first light (rear component). Excitation laser light is incident on the fifth nonlinear optical crystal 26. The fifth nonlinear optical crystal 26 is inclined with respect to the optical path of the incident excitation laser beam, and the excitation laser beam is refracted and shifted upward on the paper surface of FIG. Moreover, the fourth nonlinear optical crystal 24 and the fifth nonlinear optical crystal 26 are line symmetric and are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). Therefore, when the first light (rear component) is emitted from the fifth nonlinear optical crystal 26, the first light (rear component) travels on the extension line of the optical path P0 (that is, the optical path P3). That is, when the first light (rear component) is emitted from the fifth nonlinear optical crystal 26, it proceeds on the extended line of the optical path P0. The subsequent steps are the same as in the first embodiment, and the description thereof is omitted (see FIG. 2). As in the first embodiment, the optical path P1 of the first light (rear component) that passes through the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 and travels toward the second mirror 42 is the fourth nonlinear optical crystal ( The first light generating means) 24 is on an extension of the optical path P0 of the excitation laser light received by the first light generating means) 24.

  FIG. 8 is a diagram illustrating an optical path of the second light (front component). The excitation laser light traveling on the extension line of the optical path P0 is incident on the second nonlinear optical crystal 32. The second nonlinear optical crystal 32 is inclined with respect to the optical path of the incident first light, and the excitation laser light is refracted and shifted downward on the paper surface of FIG. Therefore, when the second light (front component) is emitted from the second nonlinear optical crystal 32, the second light (front component) is separated downward from the extension line of the optical path P0 on the paper surface of FIG. The light travels in parallel and enters the third nonlinear optical crystal 34. Since the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric, they are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). When two lights (front component) are emitted, the light travels on an extension line of the optical path P0. That is, the optical path P2 of the second light traveling from the second nonlinear optical crystal 32 to the second mirror 42 is on an extension line of the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22.

  FIG. 9 is a diagram illustrating an optical path of the second light (rear component). Excitation laser light is incident on the third nonlinear optical crystal 34. The third nonlinear optical crystal 34 is inclined with respect to the optical path of the incident excitation laser light, and the excitation laser light is refracted and shifted upward on the paper surface of FIG. Moreover, the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 are line symmetric and are inclined at the same angle with respect to the optical path P0 (however, the inclination directions are different). Therefore, when the second light (rear component) is emitted from the third nonlinear optical crystal 34, the second light (rear component) travels on the extension line of the optical path P0. That is, the optical path P2 of the second light traveling from the third nonlinear optical crystal 34 to the second mirror 42 is on an extension line of the optical path P0 of the excitation laser light received by the first nonlinear optical crystal 22.

  Therefore, the first light and the second light traveling from the third nonlinear optical crystal 34 toward the second mirror 42 are overlapped on the extension line of the optical path P0 (the optical path P1 and the optical path P2). Since there is an optical path P3 (the optical path of the first light from the fifth nonlinear optical crystal 26 to the second nonlinear optical crystal 32 (see FIGS. 6 and 7)) on the extended line of the optical path P0, the third nonlinear optical crystal 34 It can be said that the first light and the second light traveling from the first to the second mirror 42 overlap on the extension line of the optical path P3.

  According to the second embodiment, similarly to the first embodiment, the optical paths of light of two types of wavelengths (first light and second light) can be kept constant. In addition, since the angle of inclination of the fourth nonlinear optical crystal 24 with respect to the optical path P0 can be changed, the wavelength of the first light can be changed.

Third Embodiment In the third embodiment, a laser is injected to narrow the band of the two-wavelength light L obtained by the first embodiment.

  FIG. 10 is a diagram showing a configuration of the light generation apparatus 1 according to the third embodiment of the present invention. The light generation apparatus 1 according to the third embodiment includes an excitation laser light source 10, a first mirror 12, a first nonlinear optical crystal (first light generation unit) 22, and a second nonlinear optical crystal (second light generation unit) 32. , Third nonlinear optical crystal (second light generation means) 34, second mirror 42, fixed wavelength laser light source (first laser light source) 52, variable wavelength laser light source (second laser light source) 54, optical multiplexer 56, mirror (Light injection means) 58 is provided. Hereinafter, the same parts as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Excitation laser light source 10, first mirror 12, first nonlinear optical crystal (first light generation means) 22, second nonlinear optical crystal (second light generation means) 32, third nonlinear optical crystal (second light generation means) 34 and the second mirror 42 are the same as those in the first embodiment, and a description thereof will be omitted.

  The fixed wavelength laser light source (first laser light source) 52 generates the first laser light. The first laser light has a narrow line width and good frequency stability. The narrow line width here is a width (for example, 100 MHz) narrower than the line width (for example, 10 to 50 GHz) of the two-wavelength light L. The first laser light is used for injection locking of the idler light component or signal light component of the first light.

  The variable wavelength laser light source (second laser light source) 54 generates second laser light. The second laser beam has a narrow line width and good frequency stability. The narrow line width here is a width (for example, 100 MHz) narrower than the line width (for example, 10 to 50 GHz) of the two-wavelength light L. The second laser light is used for injection locking of the idler light component or signal light component of the second light. The wavelength of the second laser light is preferably variable. The wavelength of the second light may be changed by changing the inclination of the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34 with respect to the traveling direction of the excitation laser light. This is because the wavelength of the second laser beam is also changed correspondingly.

  For example, the second mirror 42 reflects the idler light component of the first light and the idler light component of the second light with a reflectance of 40% to 90%, and the signal light component of the first light and the signal of the second light are reflected. It is assumed that the light component is totally reflected. In this case, the first laser light is used for injection locking of the idler light component of the first light. Therefore, the wavelength of the first laser light is the same as the wavelength of the idler light component of the first light. The second laser light is used for injection locking of the idler light component of the second light. Therefore, the wavelength of the second laser light is the same as the wavelength of the idler light component of the second light.

  For example, the second mirror 42 reflects the signal light component of the first light and the signal light component of the second light with a reflectance of 40% or more and 90% or less, and the idler component of the first light and the idler of the second light. It is assumed that the light component is totally reflected. In this case, the first laser light is used for injection locking of the signal light component of the first light. Therefore, the wavelength of the first laser light is the same as the wavelength of the signal light component of the first light. The second laser light is used for injection locking of the signal light component of the second light. Therefore, the wavelength of the second laser light is the same as the wavelength of the signal light component of the second light.

  As the fixed wavelength laser light source 52 and the variable wavelength laser light source 54, a commercially available 1.3 μm band or 1.5 μm band external cavity semiconductor laser, DFB laser, frequency synthesizer, or the like can be used.

  The optical multiplexer 56 combines the first laser beam and the second laser beam.

  The mirror (light injection means) 58 is for injecting the output of the optical multiplexer 56 into the optical path of the excitation laser light in the first nonlinear optical crystal 22, the second nonlinear optical crystal 32, and the third nonlinear optical crystal 34. is there. The mirror 58 is, for example, a half mirror that is inclined 45 degrees with respect to the traveling direction of the two-wavelength light L. The traveling direction of the light output from the optical multiplexer 56 is orthogonal to the traveling direction of the two-wavelength light L. The mirror 58 transmits the two-wavelength light L that has passed through the second mirror 42. Further, the mirror 58 reflects the output of the optical multiplexer 56 and travels in the direction opposite to the two-wavelength light L on the optical path of the two-wavelength light L.

  Next, the operation of the third embodiment will be described.

  Since the operation until the two-wavelength light L passes through the second mirror 42 is the same as the operation of the first embodiment, the description thereof is omitted.

  The fixed wavelength laser light generated by the fixed wavelength laser light source 52 and the variable wavelength laser light generated by the variable wavelength laser light source 54 are combined by the optical multiplexer 56 and reflected by the mirror 58. The light reflected by the mirror 58 (the light combined by the optical multiplexer 56) travels in the opposite direction to the two-wavelength light L on the optical path of the two-wavelength light L, and partially passes through the second mirror 42. To Penetrate. Then, it travels in the reverse direction of the optical path of the excitation laser light and passes through the third nonlinear optical crystal 34, the second nonlinear optical crystal 32, and the first nonlinear optical crystal 22. Thereby, the light combined by the optical multiplexer 56 is injected into the optical path of the excitation laser light in the first nonlinear optical crystal 22, the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34.

  According to the third embodiment, similarly to the first embodiment, it is possible to keep the optical paths of two types of wavelengths of light (first light and second light) constant. In addition, the band of the two-wavelength light L can be narrowed. For example, the line width (for example, 10 to 50 GHz) of the two-wavelength light L can be made narrower (for example, 100 MHz).

  In the third embodiment, the light combined by the optical multiplexer 56 is advanced in the opposite direction to the two-wavelength light L on the optical path of the two-wavelength light L. And 2 are also conceivable. It should be noted that the same effects as those of the second embodiment are also obtained by the modifications 1 and 2.

  FIG. 14 is a diagram illustrating a first modification of the third embodiment. Excitation laser light source 10, first mirror 12, first nonlinear optical crystal 22, second nonlinear optical crystal 32, third nonlinear optical crystal 34, second mirror 42, fixed wavelength laser light source 52, variable wavelength laser light source 54, optical multiplexing The vessel 56 is the same as in the first embodiment, and a description thereof is omitted.

  The mirror (light injection means) 58 is disposed between the excitation laser light source 10 and the first mirror 12. The mirror 58 is, for example, a half mirror that is inclined 45 degrees with respect to the traveling direction of the excitation laser light traveling from the excitation laser light source 10 toward the first mirror 12. The traveling direction of the light output from the optical multiplexer 56 is orthogonal to the traveling direction of the excitation laser light traveling from the excitation laser light source 10 toward the first mirror 12.

  The operation of the first modification of the third embodiment will be described.

  Excitation laser light is output from the excitation laser light source 10 and travels toward the first mirror 12 and further toward the first nonlinear optical crystal 22.

  The mirror (light injection means) 58 receives excitation laser light from the excitation laser light source 10 toward the first mirror 12. The mirror 58 transmits the excitation laser light. In addition, the mirror 58 reflects the output of the optical multiplexer 56 and travels on the optical path of the excitation laser light in the same direction as the excitation laser light. The output of the optical multiplexer 56 travels on the optical path of the excitation laser light incident on the first nonlinear optical crystal 22 and is incident on the first nonlinear optical crystal 22. Then, the light travels on the optical path of the excitation laser light in the first nonlinear optical crystal 22, is emitted from the first nonlinear optical crystal 22, and enters the second nonlinear optical crystal 32. Then, it travels on the optical path of the excitation laser light in the second nonlinear optical crystal 32. Further, the light is emitted from the second nonlinear optical crystal 32 and is incident on the third nonlinear optical crystal 34. Then, it travels on the optical path of the excitation laser light in the third nonlinear optical crystal 34. Thereby, the light combined by the optical multiplexer 56 is injected into the optical path of the excitation laser light in the first nonlinear optical crystal 22, the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34.

  FIG. 15 is a diagram illustrating a second modification of the third embodiment. Excitation laser light source 10, first mirror 12, first nonlinear optical crystal 22, second nonlinear optical crystal 32, third nonlinear optical crystal 34, second mirror 42, fixed wavelength laser light source 52, variable wavelength laser light source 54, optical multiplexing The vessel 56 is the same as in the first embodiment, and a description thereof is omitted.

  The mirror (light injection means) 58 is disposed between the first mirror 12 and the first nonlinear optical crystal 22. The mirror 58 is, for example, a half mirror that is inclined 45 degrees with respect to the traveling direction of the excitation laser light traveling from the excitation laser light source 10 toward the first nonlinear optical crystal 22. The traveling direction of the light output from the optical multiplexer 56 is orthogonal to the traveling direction of the excitation laser light traveling from the excitation laser light source 10 toward the first nonlinear optical crystal 22.

  The operation of Modification 2 of the third embodiment will be described.

  Excitation laser light is output from the excitation laser light source 10, passes through the first mirror 12, and further travels toward the first nonlinear optical crystal 22.

  The mirror (light injection means) 58 transmits the excitation laser light from the excitation laser light source 10 through the first mirror 12 and further toward the first nonlinear optical crystal 22. The mirror 58 transmits the excitation laser light. In addition, the mirror 58 reflects the output of the optical multiplexer 56 and travels on the optical path of the excitation laser light in the same direction as the excitation laser light. The output of the optical multiplexer 56 travels on the optical path of the excitation laser light incident on the first nonlinear optical crystal 22 and is incident on the first nonlinear optical crystal 22. Then, the light travels on the optical path of the excitation laser light in the first nonlinear optical crystal 22, is emitted from the first nonlinear optical crystal 22, and enters the second nonlinear optical crystal 32. Then, it travels on the optical path of the excitation laser light in the second nonlinear optical crystal 32. Further, the light is emitted from the second nonlinear optical crystal 32 and is incident on the third nonlinear optical crystal 34. Then, it travels on the optical path of the excitation laser light in the third nonlinear optical crystal 34. Thereby, the light combined by the optical multiplexer 56 is injected into the optical path of the excitation laser light in the first nonlinear optical crystal 22, the second nonlinear optical crystal 32 and the third nonlinear optical crystal 34.

Fourth Embodiment In the fourth embodiment, a laser is injected to narrow the band of the two-wavelength light L obtained by the second embodiment.

  FIG. 11 is a diagram showing a configuration of the light generation apparatus 1 according to the fourth embodiment of the present invention. The light generation apparatus 1 according to the fourth embodiment includes an excitation laser light source 10, a first mirror 12, a fourth nonlinear optical crystal (first light generation unit) 24, and a fifth nonlinear optical crystal (first light generation unit) 26. , Second nonlinear optical crystal (second light generation means) 32, third nonlinear optical crystal (second light generation means) 34, second mirror 42, fixed wavelength laser light source 52, variable wavelength laser light source 54, optical multiplexer 56 , A mirror (light injection means) 58 is provided. Hereinafter, the same parts as those of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Excitation laser light source 10, first mirror 12, fourth nonlinear optical crystal (first light generation means) 24, fifth nonlinear optical crystal (first light generation means) 26, second nonlinear optical crystal (second light generation means) 32, the third nonlinear optical crystal (second light generating means) 34 and the second mirror 42 are the same as those in the second embodiment, and the description thereof is omitted.

  The fixed wavelength laser light source 52, the variable wavelength laser light source 54, the optical multiplexer 56, and the mirror (light injection means) 58 are the same as in the third embodiment, and a description thereof is omitted.

  Next, the operation of the fourth embodiment will be described.

  Since the operation until the two-wavelength light L passes through the second mirror 42 is the same as the operation of the second embodiment, the description thereof is omitted.

  The fixed wavelength laser light generated by the fixed wavelength laser light source 52 and the variable wavelength laser light generated by the variable wavelength laser light source 54 are combined by the optical multiplexer 56 and reflected by the mirror 58. The light reflected by the mirror 58 (the light combined by the optical multiplexer 56) travels in the opposite direction to the two-wavelength light L on the optical path of the two-wavelength light L, and partially passes through the second mirror 42. To Penetrate. Then, the optical path of the excitation laser light travels in the opposite direction and passes through the third nonlinear optical crystal 34, the second nonlinear optical crystal 32, the fifth nonlinear optical crystal 26 and the fourth nonlinear optical crystal 24. Thereby, the light combined by the optical multiplexer 56 is injected into the optical path of the excitation laser light in the fourth nonlinear optical crystal 24, the fifth nonlinear optical crystal 26, the second nonlinear optical crystal 32, and the third nonlinear optical crystal 34. Is done.

  According to the fourth embodiment, similarly to the second embodiment, the optical paths of light of two types of wavelengths (first light and second light) can be kept constant. In addition, the band of the two-wavelength light L can be narrowed. For example, the line width (for example, 10 to 50 GHz) of the two-wavelength light L can be made narrower (for example, 100 MHz).

  As in the first and second modifications of the third embodiment, the mirror 58 may be disposed between the excitation laser light source 10 and the first mirror 12, or the first mirror 12 and the fourth nonlinear optical crystal. You may arrange | position between 24.

Fifth Embodiment In the fifth embodiment, a sixth nonlinear optical crystal (difference frequency light generating means) 64 is added to the first embodiment to output a terahertz wave.

  FIG. 12 is a diagram showing a configuration of the light generation apparatus 1 according to the fifth embodiment of the present invention. The light generation apparatus 1 according to the fifth embodiment includes an excitation laser light source 10, a first mirror 12, a first nonlinear optical crystal (first light generation unit) 22, and a second nonlinear optical crystal (second light generation unit) 32. , A third nonlinear optical crystal (second light generation means) 34, a second mirror 42, a lens 62, a sixth nonlinear optical crystal (difference frequency light generation means) 64, a filter 66, and a terahertz wave detector 68. Hereinafter, the same parts as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Excitation laser light source 10, first mirror 12, first nonlinear optical crystal (first light generation means) 22, second nonlinear optical crystal (second light generation means) 32, third nonlinear optical crystal (second light generation means) 34 and the second mirror 42 are the same as those in the first embodiment, and a description thereof will be omitted.

  The lens 62 condenses the two-wavelength light L transmitted through the second mirror 42 on the sixth nonlinear optical crystal 64.

The sixth nonlinear optical crystal (difference frequency light generating means) 64 includes the optical frequency of the first idler light component (or signal light component) of the two-wavelength light L and the idler light component (or signal light component) of the second light. ) To generate a difference frequency light L _THz having an optical frequency corresponding to a difference from the optical frequency of (). In general, the difference frequency light L _THz is terahertz light. As the sixth nonlinear optical crystal 64, a crystal such as GaSe, GaP, LiNbO ₃ (abbreviation LN), ZnGeP ₂ (abbreviation ZGP) 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (abbreviation DAST) is used. be able to.

When the two-wavelength light L has an idler light component of the first light and an idler light component of the second light, the optical frequency of the difference frequency light L _THz is equal to the optical frequency of the idler light component of the first light and the second light frequency. It is the difference from the optical frequency of the idler light component of light.

When the two-wavelength light L has the signal light component of the first light and the signal light component of the second light, the optical frequency of the difference frequency light L _THz is equal to the optical frequency of the signal light component of the first light. It is the difference from the optical frequency of the signal light component of light.

The filter 66 blocks the two-wavelength light L transmitted through the sixth nonlinear optical crystal 64 and transmits the difference frequency light L _THz .

The terahertz wave detector 68 detects the light intensity of the difference frequency light L _THz transmitted through the filter 66.

  A sample to be measured may be disposed between the sixth nonlinear optical crystal 64 and the filter 66. In this case, the transmission intensity of the sample to be measured with respect to the terahertz wave is measured, and an absorption spectrum measuring apparatus in the terahertz wave band (frequency range of 0.1 to 100 THz) can be realized.

  Next, the operation of the fifth embodiment will be described.

  Since the operation until the two-wavelength light L passes through the second mirror 42 is the same as the operation of the first embodiment, the description thereof is omitted.

The two-wavelength light L is condensed on the sixth nonlinear optical crystal 64 by the lens 62. The sixth nonlinear optical crystal 64 receives the two-wavelength light L and generates the difference frequency light L _THz . The difference frequency light passes through the filter 66, while blocking the two-wavelength light L that has passed through the sixth nonlinear optical crystal 64. The terahertz wave detector 68 detects the light intensity of the difference frequency light that has passed through the filter 66.

  According to the fifth embodiment, terahertz waves can be generated and detected.

  In the fifth embodiment, the fixed wavelength laser light source 52, the variable wavelength laser light source 54, the optical multiplexer 56, and the mirror 58 described in the third embodiment are replaced with the second mirror 42 and the sixth nonlinear optical crystal 64. You may add so that the mirror 58 may be arrange | positioned between these.

  Furthermore, the lens 62, the sixth nonlinear optical crystal 64, the filter 66, and the terahertz wave detector 68 may be added to the second embodiment or the fourth embodiment.

It is a figure which shows the structure of the light generation apparatus 1 concerning 1st embodiment of this invention. It is a figure which shows the optical path of 1st light. It is a figure which shows the optical path of 2nd light (front component). It is a figure which shows the optical path of 2nd light (back component). It is a figure which shows the structure of the light generation apparatus 1 concerning 2nd embodiment of this invention. It is a figure which shows the optical path of 1st light (front component). It is a figure which shows the optical path of 1st light (back component). It is a figure which shows the optical path of 2nd light (front component). It is a figure which shows the optical path of 2nd light (back component). It is a figure which shows the structure of the light generation apparatus 1 concerning 3rd embodiment of this invention. It is a figure which shows the structure of the light generation apparatus 1 concerning 4th embodiment of this invention. It is a figure which shows the structure of the light generation apparatus 1 concerning 5th embodiment of this invention. It is a figure which shows the optical path of the 1st light and the 2nd light in the comparative example when there is no 3rd nonlinear optical crystal. It is a figure which shows the modification 1 of 3rd embodiment. It is a figure which shows the modification 2 of 3rd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light production | generation apparatus 10 Excitation laser light source 12 1st mirror 22 1st nonlinear optical crystal (1st light production | generation means)
24 Fourth nonlinear optical crystal (first light generating means)
26 Fifth nonlinear optical crystal (first light generating means)
32 Second nonlinear optical crystal (second light generating means)
34 Third nonlinear optical crystal (second light generating means)
42 Second mirror 52 Fixed wavelength laser light source (first laser light source)
54 Variable wavelength laser light source (second laser light source)
56 Optical multiplexer 58 Mirror (light injection means)
62 Lens 64 Sixth nonlinear optical crystal (difference frequency light generating means)
66 filter 68 terahertz wave detector
P0, P1, P2, P3 optical path
S, S1, S2 orthogonal line L dual wavelength light
L _THz difference frequency light

Claims (5)

An excitation laser light source for generating excitation laser light;
A first mirror having a reflectance with respect to the excitation laser light lower than a reflectance with respect to light having a wavelength different from that of the excitation laser light;
First light generating means for generating first light by optical parametric conversion caused by receiving the excitation laser light transmitted through the first mirror;
Second light generating means for transmitting the first light and generating second light by optical parametric conversion generated by receiving the excitation laser light transmitted through the first mirror and the first light generating means;
A second mirror that partially reflects the first light and the second light and returns them to the second light generating means;
With
An optical path of the first light that passes through the second light generation unit and travels toward the second mirror, and an optical path of the second light that travels from the second light generation unit toward the second mirror includes the first light extension on the near the optical path of the first light from the generating means toward the second light generating means is,
The light traveling back and forth between the first mirror and the second mirror causes resonance,
The second mirror is a light generation device that reflects the idler light component of the first light and the idler light component of the second light with a reflectance of 40% or more and 90% or less,
The light generation device further includes:
A first laser light source that generates a first laser light having the same wavelength as the idler light component of the first light;
A second laser light source for generating a second laser light having the same wavelength as the idler light component of the second light;
An optical multiplexer for combining the first laser light and the second laser light;
Light injection means for injecting the output of the optical multiplexer into the optical path of the excitation laser light in the first light generation means and the second light generation means;
Light generator with. An excitation laser light source for generating excitation laser light;
A first mirror having a reflectance with respect to the excitation laser light lower than a reflectance with respect to light having a wavelength different from that of the excitation laser light;
First light generating means for generating first light by optical parametric conversion caused by receiving the excitation laser light transmitted through the first mirror;
Second light generating means for transmitting the first light and generating second light by optical parametric conversion generated by receiving the excitation laser light transmitted through the first mirror and the first light generating means;
A second mirror that partially reflects the first light and the second light and returns them to the second light generating means;
With
An optical path of the first light that passes through the second light generation unit and travels toward the second mirror, and an optical path of the second light that travels from the second light generation unit toward the second mirror includes the first light extension on the near the optical path of the first light from the generating means toward the second light generating means is,
The light traveling back and forth between the first mirror and the second mirror causes resonance,
The partial reflection mirror is a light generation device that reflects the signal light component of the first light and the signal light component of the second light with a reflectance of 40% or more and 90% or less,
The light generation device further includes:
A first laser light source that generates a first laser beam having the same wavelength as the signal light component of the first light;
A second laser light source that generates a second laser beam having the same wavelength as the signal light component of the second light;
An optical multiplexer for combining the first laser light and the second laser light;
Light injection means for injecting the output of the optical multiplexer into the optical path of the excitation laser light in the first light generation means and the second light generation means;
A light generation apparatus comprising: The light generation device according to claim 1 or 2 ,
The light injection means includes
Transmitting the light transmitted through the second mirror,
Reflecting the output of the optical multiplexer, and traveling the light path of the light transmitted through the second mirror in the direction opposite to the light transmitted through the second mirror;
Light generator. The light generation device according to claim 1 or 2 ,
The light injection means includes
Transmitting the excitation laser light from the excitation laser light source toward the first light generation means,
Reflecting the output of the optical multiplexer, and traveling the optical path of the pump laser light in the same direction as the pump laser light,
Light generator. The light generation device according to any one of claims 1 to 4 ,
Difference frequency light generating means for receiving light transmitted through the second mirror and generating difference frequency light having an optical frequency corresponding to a difference between optical frequencies of two light components of the light transmitted through the second mirror;
A terahertz light generating device.

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