JPS58196B2 - Wavelength multiplexing laser oscillation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a wavelength multiplexing laser oscillation device that can simultaneously obtain at least two laser oscillation lights having different wavelength bands.

Such a wavelength multiplexed laser oscillation device is useful as a light source for an optical transmission system.

As shown in FIG. 1, a conventional wavelength multiplexed laser oscillation device includes a resonator A1 using a semiconductor that can obtain a first laser oscillation in a first wavelength band (generally referred to as A1), and a second resonator A1.
A second laser oscillation in a wavelength band (generally referred to as A2) is obtained by providing at least two resonators A2, which are also made of a semiconductor, in parallel; Laser oscillation lights L1 and L2 having first and second wavelength bands λ1 and A2 obtained from A2 and A2 are guided to a common waveguide via an optical coupler B, and from this waveguide, It has been common practice to simultaneously obtain laser oscillation lights L1 and L2 having different wavelength bands λ and A2.

However, in the case of such a conventional wavelength multiplexing laser oscillation device, at least two resonators and a coupler are required in order to simultaneously obtain at least two laser oscillation lights in different wavelength bands. Therefore, the entire device has the disadvantage of becoming large and complicated.

In addition, it is difficult to guide the laser oscillation light obtained from the two resonators to the waveguide via the coupler without loss.
Therefore, at least two laser oscillation lights can be efficiently transmitted.
It has the disadvantage that it cannot be obtained at the same time.

In view of the above, the present inventor conducted various considerations and experiments, and found that in a laser crystal in which laser oscillation is obtained by pumping with pumping light, the laser oscillation is caused by at least first and second crystals that are different from each other. Wavelength band (each of these is λ
1 and λ2) respectively obtained as the first and second laser oscillations, Nd-YAG, LiNdP4O
12, Nd-YAlO3, Nd-11YF4. KNdP
For the first and second wavelength bands λ1 and λ2 of the first and second oscillations obtained using a Nd-based laser crystal such as 4O12°NaNdP4O12, as shown with reference numeral 1 in FIG. A resonator M is arranged between mirrors G1 and G2, which are arranged opposite to each other and exhibit substantially equal reflectances γ. When oscillation is obtained, the threshold value of the pumping light to the laser crystal 1 is Pl, and the laser transition cross section in the first and second wavelength bands λ1 and λ2 of the laser crystal 1 (these are G1 and G2, respectively) When the ratio σ1/σ2 of R1 resonator M in the first and second wavelength bands λ1 and λ2 (these are Ql and G2, respectively) is the ratio Q1/Q2 of the laser crystal 1, If pumping by the pumping light indicated by the symbol 2 is performed with a value P that satisfies the relationship expressed by 1 and the second oscillation are obtained simultaneously, and therefore at least the first oscillation having the first and second wavelength bands λ1 and λ2
It has now been confirmed that the second oscillation lights L1 and R2 can be obtained at the same time, and that they can be led to the outside through, for example, either one of the reflecting mirrors G1 and G2.

However, in this case, the losses Q1 and G2 mentioned above are the non-resonant losses per round trip of the resonator M (however, the losses Q1 and G2
(including the transmission loss at
, where α1 and G2 are the resonance absorption loss coefficients of the laser crystal 1 in the first and second wavelength bands λ1 and λ2, respectively.

The above-mentioned equations (1), (2), and (3) were determined by the inventor from the following viewpoint.

(b) In the case of the configuration of the wavelength multiplexing laser oscillation device described above in FIG. When only the first and second oscillations having the first and second wavelength bands λ1 and λ2 are considered, the above-mentioned first and second oscillations
This can be analyzed using the following rate equation, which is the same as for a multi-wavelength laser considering only the first and second oscillations with wavelength bands λ1 and λ2.

Here, W in equation (6) is the same P/P1 as expressed in equation (1) above; no, nl, and R2 are reflection distributions normalized by the threshold; S1 and S2 are The oscillation photon density in the first and second wavelength bands λ1 and λ2 described above, respectively; R is the ratio of the laser transition cross section, which is the same as described above;
a are the same first and second wavelength bands λ1 and λ2 as described above.
shows the same loss ratio as in .

(b) Therefore, if the left sides of equations (6) to (10) are set to zero, the steady state values of no, nl, and R2 described above in the case of the configuration of the wavelength division multiplexing laser oscillation device shown in FIG. It is possible to obtain the values of S1 and S2 in a steady state (these are referred to as S1 and S2, respectively).

(c) Furthermore, if S1 and S2 can be determined, the following relational expression can be determined from these S1 and S2.

) Furthermore, if equation (11) can be obtained, from equation (11), aR that satisfies that both S1 and S2 are positive, that is, can be calculated from equation (3) above. You can ask like this.

(E) Furthermore, if the above-mentioned equation (11) can be obtained, the following relational expression can be obtained from the above-mentioned equation (11) and the above-mentioned equations (6) to (10).

Here, α is a coefficient expressed by the following equation that includes only a and R, and is expressed as a positive real number when aR satisfies the above-mentioned equation (13).

Further, β is a coefficient expressed by the following equation including a, R, and W.

Furthermore, like β, γ is a coefficient expressed by the following equation including a, R, and W.

(v) Also, if we can find equation (14), we can find the root of S2 from equation (14) as expressed by:

(g) Furthermore, if equation (18) can be found, from equation (18), W that satisfies that S2 is a positive real number can be found using equation (2) above, that is, as follows. I can do it.

Note that in equation (19), α in equation (18) is expressed as a positive real number as described above, and therefore, the denominator on the right side of equation (18) is expressed as a positive real number, so (18) It can be found by assuming that the numerator of the equation is a positive real number.

(h) Furthermore, if W has the relationship of formula (19), then formula (19) satisfies formula (12), and using formula (13) described above, Since it was obtained as shown above, it satisfies that S1 is also a positive real number.

(S) On the other hand, if both S1 and S2 are positive real numbers, in the configuration of the wavelength multiplexed laser oscillation device shown in FIG. The second oscillation can be similarly obtained.

(N) Therefore, W in the above equation (6) is W=P/
P1, and the above-mentioned equations (13) and (19) are obtained as the above-mentioned equations (1) to (3).

Therefore, we have hereby proposed the present invention as set forth in the claims.

The configuration of the wavelength multiplexed laser oscillation device according to the present invention has been clarified above.

According to the configuration of the wavelength multiplexing laser oscillation device according to the present invention, as is clear from the above, at least two laser oscillation lights in mutually different wavelength bands can be transmitted through one resonator M. , and at the same time can be easily obtained without requiring a coupler as in the conventional case described above in FIG.

Therefore, according to the wavelength division multiplexing laser oscillation device according to the present invention, at least two laser oscillation lights having mutually different wavelength bands can be efficiently and simultaneously obtained without making the entire device large and complicated. It has the great feature of being able to.

Next, an embodiment of a wavelength multiplexed laser oscillation device according to the present invention will be described.

Nd-YAG is used as the Nd-based laser crystal 1.

LiNdP4O12, Nd-YAlO3, Nd-LiY
F4゜KNdP4O12, NaNdP4O12, etc., transition 4F3/2 → 4111/2; and transition 4F3/2 → 1
Based on 13/2, 1.04 μm, 1.055 μm, 1
．． 1.05 μm band such as 060 μm; and 1.32 μm band laser oscillation is obtained, the above-mentioned ratio R=σ1/σ2 is about 0.2, and α1 in equations (4) and (5) is 0.07 vm.
-1 and α2 are 6×10 −7 cm −1 (α1 and α2 are proportional to the lower level 4111/2 Nd ion concentration of the Nd-based laser crystal.

), a Nd-based laser crystal with l of 5 mm was used, and the resonator M was constructed so that F in equations (4) and (5) was 0.01.

Then, the laser crystal 1 was pumped by the pumping light 2 so that the relationship W>1.36 was obtained in terms of the value of W.

In such a case, the first laser oscillation light L1 having the first wavelength band λ1 of 1.05 μm and the second wavelength band λ2 of 1.05 μm
．． It was possible to simultaneously obtain the second laser oscillation light L2 in the 32 μm band.

[Brief explanation of the drawing]

FIG. 1 is a route map showing a conventional wavelength multiplexed laser oscillation device. FIG. 2 is a route map showing an example of a wavelength multiplexed laser oscillation device according to the present invention. 1...Laser crystal, 2...Pumping light, G1゜G2...Reflector.

Claims (1)

[Claims] 1. A Nd-based laser crystal that can obtain at least first and second laser oscillations in mutually different first and second wavelength bands by pumping with pumping light is used for the first and second wavelength bands. A resonator is configured by disposing between first and second reflecting mirrors facing each other and exhibiting substantially equal reflectance, and laser oscillation in the first wavelength band is obtained by the resonator. , the threshold value of the pumping light is Pl, and the ratio of the laser transition cross sections in the first and second wavelength bands of the laser crystal is R1, the ratio of the laser transition cross sections in the first and second wavelength bands of the resonator When the ratio of losses in the laser beam is a, the pumping by the pumping light is performed with a value P that satisfies the relationship expressed by, and the resonator generates at least the first and second laser oscillations. A wavelength multiplexing laser oscillation device characterized in that it is configured to simultaneously obtain at least two laser oscillation lights having the first and second wavelength bands.