JP3268074B2 - Dye flow cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye laser device, and more particularly to a dye flow cell used for a dye laser amplifier.

[0002]

2. Description of the Related Art FIG. 4 is an overall configuration diagram of a dye laser device. The excitation laser light p output from the excitation laser oscillator 2 is reflected by the beam splitter 3 to enter the dye laser oscillator 1, and the irradiation of the excitation laser light p excites the dye solution to output the dye laser light s. Is done.

At the same time, the excitation laser light p is branched by the beam splitter 4 and one of the excitation laser lights p
1 enters the dye laser amplifier 6 through the mirror 5, and the other excitation laser light p2 enters the dye laser amplifier 6 through the mirrors 7 and 8.

In the dye laser amplifier 6, the dye solution is excited by the incidence of each of the excitation laser beams p1 and p2, and is amplified and output by the incidence of the dye laser beam s. Here, as shown in FIG. 5, the dye laser amplifier 6 is formed of a light transmissive material, for example, a transparent glass material, and is a so-called dye flow cell. In the dye flow cell 6, a dye flow path 9 having a rectangular cross-sectional shape is formed, and a dye solution 10 flows in the dye flow path 9 in the direction of the arrow (a).

Accordingly, as described above, each of the pump laser beams p1,
p2 is incident from both sides of the dye flow cell 6 and the dye solution 1
When 0 is excited and the dye laser light s is incident on the excitation region, the dye laser light s is amplified and output.

However, each of the pump laser beams p1, p2
Distribution of the excited dye density excited by the dye solution is minimized at the center of the dye flow channel 9 of the dye flow cell 6, and the dye solution 10
And the surface of the dye flow path 9 (glass surface), and the ratio is about 1: 1.5.

This will be described with reference to the schematic diagram of the excitation dye density distribution shown in FIG. 6. If the excitation dye densities due to the incidence of each excitation laser beam from each direction L and R are n1 and n2, weak excitation approximation Is given by

N1 = N · Ts · σ · Ip (x); Ip (x) = Ipo · Exp [−Nσx] (1) n2 = N · Ts · σ · Ip ′ (x); Ip ′ (x ) = Ipo · Exp [-Nσ ( dx)] ... (2) in addition, N is the dye concentration [m ^-3], Ts dye upper level lifetime [s], sigma excitation laser light absorption cross section [m ² ], Ipo is the excitation laser light photon number density [photons s ^-1 m ^-2 ], and x is the excitation laser light incident direction [m].

Here, when the dye density at which the maximum excitation density is obtained at the center of the excitation region is obtained, it is a value represented by the following equation. N = 2 / σ · d (3) At this time, the ratio of the excitation density at the center (x = d / 2) and the end (x = 0, d) is used as an index indicating the unevenness of the distribution of the excited dye. Then, the following equation is obtained.

K = n (x = 0, d) / n (x = d / 2) = (1 + Exp [−Nσx]) / {2Exp [−nσ (d / 2)} (4) When equation (3) is substituted into (4), the value of the above ratio, that is, K = (1 + Exp [-2]) / (2Exp [-1]) = 1.54 (5).

At this time, the energy absorptivity P of the pump laser light is as follows: P = {2Ipo.Exp [-Nσd] / 2Ipo} × 100 = Exp [−2] × 100 = 13.5 [%] (6) ).

As described above, the distribution of the excited dye density is about 1: 1.5 between the center of the dye channel 9 and the boundary between the surface of the dye solution 10 and the surface of the dye channel 9. In the inside of the dye flow cell 6, strong amplification is applied from the center to the outside. For this reason, the intensity distribution of the dye laser light to be amplified has a non-uniform shape such as a concave shape having a low intensity at the center.

[0013]

As described above, the distribution of the excited dye density is such that the ratio between the center of the dye channel 9 and the boundary between the surface of the dye solution 10 and the surface of the dye channel 9 is 1: 1. As a result, the intensity distribution of the dye laser beam becomes non-uniform.

Accordingly, an object of the present invention is to provide a dye flow cell capable of reducing the non-uniformity of the excitation dye density distribution and improving the uniformity of the intensity distribution of the output dye laser light.

[0015]

According to the present invention, there is provided a dye flow cell in which a dye flow path for flowing a dye solution is formed and an excitation laser light incident surface with respect to the dye solution is formed. And the concentration of the dye solution is set based on the dye channel width and the like, and the excitation laser light is incident on the surface of the entrance surface of the excitation laser light that faces the dye laser through the dye flow channel. This is a dye flow cell which aims to achieve the above object by forming a reflective surface.

In this case, the angle θ of the incident surface of the excitation laser beam with respect to the dye channel is formed in the range of 0 ° <θ <5.5 °.

The concentration N [m ^-3 ] of the dye solution is such that the excitation laser beam absorption cross section is σ [m ² ] and the dye channel width is d [m].
Then, it is set from the relationship of N = (σd) ⁻¹ .

[0018]

With such a means, the incident surface of the excitation laser beam can be set at a predetermined angle (0 ° <θ <
(5.5 °), and the dye solution is irradiated with the excitation laser light from the incident surface, and the excitation laser light is reflected on the reflection surface at the opposing position and irradiated again with the dye solution. At this time, the inclination of the incident surface is limited within the above range so that the excitation region width on the incident surface of the excitation laser beam is 1.1 times or less with respect to the dye flow channel width. Sexual decline is prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is a configuration diagram of a dye flow cell applied to a dye laser amplifier of a dye laser device.

In the dye flow cell 20, a dye flow path 22 through which a dye solution 21 flows is formed as shown in FIG. The dye channel 22 has a rectangular cross section as described above.

The respective surfaces A, B, C, and D of the excitation laser beams p1 and p2 in the dye flow cell 20 (especially, the surfaces C and D are incident surfaces of the excitation laser beams p1 and p2) are supplied to the dye channel 22. On the other hand, it is formed with an angle θ. Specifically, the angle θ is set in the range of 0 ° <θ <5.5 °.

Each of the surfaces A and B has a high reflection coat 23,
24 are given. On the other hand, the concentration N [m ⁻³ ] of the dye solution 22 is such that the excitation laser light absorption cross section is σ [m ² ],
When the dye channel width is d [m], the value is set to a value satisfying the relationship of N = (σd) ⁻¹ (7).

With such a configuration, each excitation laser beam p
1 and p2 enter the dye flow cell 20 from a direction perpendicular to each of the incident surfaces C and D, irradiate the dye solution 21 flowing through the dye flow channel 22, and further pass through the dye solution 21 to the respective surfaces B. , A respectively. Since the surfaces B and A are coated with the high reflection coats 23 and 24, the excitation laser beams p1 and p2 are reflected by the high reflection coats 23 and 24 and irradiate the dye solution 21 again through the same optical path. Is done.

Therefore, the dye solution 21 is excited by absorbing the excitation laser beams p1 and p2 twice.
In this state, when the dye laser light s output from the dye laser oscillator 1 enters the excitation region of the dye solution 21, the dye laser light s is amplified and output.

Here, when the distribution of the excited dye density is obtained,
N1 = N · Ts · Ip (x); Ip (x) = Ipo · Exp [−Nσx] ｛1 + Exp [−Nσd]｝ (8) n2 = N · Ts as in the above equations (1) and (2). Ip '(x);Ip' (x) = Ipo.Exp [-N.sigma. (Dx)]. Times. {1 + Exp [-N.sigma.d]} (9) where the dye density N is given by the above equation (7). When set to a value, the ratio K of the excitation density at the center {x = (d / 2)} and the end (x = 0, d) of the dye channel 22 is given by the following equation.

K = n (x = 0, d) / n ｛x = (d / 2)｝ = {1 + Exp [−Nσd]} / 2Exp [−nσ (d / 2)] = ｛1 + Exp (−1) ｝ / 2Exp (− ／) = 1.13 (10) From the above, it can be seen that the excitation density ratio K is reduced.

Further, when the energy non-use rate P at this time is obtained, P = {2Ipo.Exp [-2Nσd] / 2Ipo} × 100 = Exp [-2] × 100 = 13.5 [%] (6) ). Accordingly, the energy non-utilization rate P can use the same excitation energy as the conventional apparatus.

As described above, in the first embodiment, the respective surfaces A, B, C, and D of the excitation laser beams p1 and p2 are formed with a predetermined angle with respect to the dye flow path 22. Since the density is set based on the dye channel width and the like, and the surfaces A and B are coated with the high reflection coats 23 and 24 of the excitation laser light, the center and the end (x = 0, The ratio K of the excitation density to d) can be reduced to 1.13, and the non-uniformity of the excitation dye density distribution can be reduced, thereby improving the uniformity of the intensity distribution of the output dye laser light. In addition, by absorbing the excitation laser beams p1 and p2 twice into the dye solution 21, the energy non-use rate P is made equal to that of the conventional apparatus, so that the excitation energy can be effectively used.

Next, a second embodiment of the present invention will be described with reference to the sectional constitutional view of the dye flow cell shown in FIG. In the dye flow cell 30, a dye flow channel 31 is formed in the same manner as the dye flow cell 20 shown in the first embodiment, and the respective surfaces A, B, C, and D of the excitation laser beams p1, p2 are
It is formed with an angle θ with respect to the dye channel 22. That is, the angle θ is set in the range of 0 ° <θ <5.5 °.

At a predetermined distance from each of the surfaces A and B, each of the mirrors 32 and 33 is parallel to the surfaces A and B.
Is arranged. On the other hand, the dye solution 22 has the formula (7)
Is set to the density N shown in FIG.

With such a configuration, each excitation laser beam p
1 and p2 enter the dye flow cell 20 from a direction perpendicular to each of the incident surfaces C and D, irradiate the dye solution 21 flowing in the dye flow channel 31, and further penetrate the dye solution 21 to make each surface B , A. Then, these excitation laser beams p1 and p2 are reflected by the mirrors 33 and 32, and irradiate the dye solution 21 again through the same optical path.

Therefore, the dye solution 21 is excited by absorbing the excitation laser beams p1 and p2 twice, as in the first embodiment. In this state, the dye laser light s output from the dye laser oscillator 1 enters the excitation region of the dye solution 21 so that the dye laser light s is amplified and output.

As described above, according to the second embodiment, it goes without saying that the same effects as those of the first embodiment can be obtained. The present invention is not limited to the above embodiments, and may be modified without changing the gist of the invention. For example, the present invention can be applied not only to a dye laser amplifier but also to a dye flow cell in a dye laser oscillator.

In each of the above embodiments, the respective excitation laser beams p1 and p2 are incident from the respective incident surfaces C and D. However, the respective excitation laser beams p1 and p2 are incident from the respective surfaces A and B in the vertical direction. You may make it. In this case, a high reflection coat is applied to each of the surfaces C and D, or each mirror is arranged. or,
Although the respective excitation laser beams p1 and p2 are incident from both of the incident surfaces C and D, the excitation laser beam p1 may be incident from only one of the surfaces, for example, only the surface C.

[0035]

As described above in detail, according to the present invention, it is possible to provide a dye flow cell capable of reducing the non-uniformity of the excitation dye density distribution and improving the uniformity of the intensity distribution of the output dye laser light.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment in which a dye flow cell according to the present invention is applied to a dye laser device.

FIG. 2 is a specific configuration diagram of the dye flow cell.

FIG. 3 is a configuration diagram showing a second embodiment of the dye flow cell.

FIG. 4 is a configuration diagram of a dye laser device.

FIG. 5 is a configuration diagram of a conventional dye flow cell.

FIG. 6 is a schematic diagram showing excited dye density.

[Explanation of symbols]

20, 30 ... dye flow cell, 21, 31 ... dye solution,
22: dye channel, 23, 24: high reflection coating.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-91285 (JP, A) JP-A-4-103188 (JP, A) JP-A-52-50193 (JP, A) JP-A-5-193 291660 (JP, A) JP 42-23393 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/00-3/30

Claims (3)

(57) [Claims] 1. A dye flow cell in which a dye flow path for flowing a dye solution is formed and an excitation laser light incident surface with respect to the dye solution is formed, wherein the excitation laser light incident surface is at a predetermined angle with respect to the dye flow path. The concentration of the dye solution is set based on the dye flow path width and the like, and the excitation laser light is applied to a surface of the excitation laser light incident surface that faces the dye laser flow path through the dye flow path. A dye flow cell, which forms a reflective surface. 2. The dye flow cell according to claim 1, wherein the incident surface of the excitation laser beam is formed at an angle θ 0 ° <θ <5.5 ° with respect to the dye flow path. 3. A relation of N = (σd) ⁻¹ where a concentration N [m ⁻³ ] of the dye solution is an excitation laser beam absorption cross section σ [m ² ] and a dye channel width d [m]. 2. The dye flow cell according to claim 1, wherein the flow rate is set from the following.