JPS59105391A - Method of light amplification by use of semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain the function of shaping a light pulse wave form, of a light logical gate, and of a light memory by a method wherein a laser input light is non-linearly amplified by utilizing the S-shaped laser input power to laser output light power characteristic of a semiconductor laser. CONSTITUTION:If the laser input light S1 has a power waveform which exceeds the point at which the laser input light power takes the maximum value on the curve for the S-shaped laser input power to laser output light power characteristic, the input light S1 can be non-linearly amplified in the form of shaping to a light pulse wave form. If there are two laser input lights S1, and the sum of the powers of the two input lights have the value which exceeds the point at which the laser input light power takes the maximum value on the curve for the input light power to output light power characteristic, the laser input light S1 can be non-linearly amplified in the form of the logical gate. Further, when those of two input lights are selectively injected to an active layer 2 in the state that a bias light having the power of a medium value is injected to the active layer 2 of the semiconductor laser 1, the input light Si can be memorized by non-linear amplification in the form that the light input light taking positive and negative polarity powers corresponding to 1 and 0 in terms of binary values respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical amplification method using a semiconductor laser, which amplifies laser input light using a semiconductor laser.

The first optical amplification method using such a semiconductor laser is
As shown in the figure, the opposing end faces are male open faces.1.
A resonator-shaped semiconductor laser 1 having a configuration in which the resonator is used as a resonator, or a reflective film is attached to the end faces facing each other.
The principle is that the laser input light S1 is injected into the active layer 2 while a current below the oscillation threshold is injected from the power supply 3 into the active layer 2, and the laser input light S1 is amplified from the active layer 2. Optical amplification methods have been proposed.

In the optical amplification method using such a principle semiconductor laser, conventionally, the laser input light S1 is linearly amplified.
It was just a method.

Therefore, according to the conventional optical amplification method based on the optical amplification method using the principle semiconductor laser shown in FIG.
It was not possible to obtain optical memory functions.

Therefore, the present invention employs an optical amplification method using a semiconductor laser based on the principle shown in FIG. This will become clear from the detailed explanation below.

In the principle optical amplification method using a semiconductor laser shown in FIG. 1, the power gain G of the semiconductor laser 1 expressed as the ratio of the power P of the laser input light S1 and the power P2 of the laser output light S2 is , is expressed by the following equation.

However, for the sake of simplicity, the following description will be made assuming that the semiconductor laser 1 has the open planes 9 through 9 serving as resonators.

G engineering = P, /P.

=ηT' G (1-RG)' X (1+Fsin' φ) ・・・・・・・・・・・・・・・(1) F=4GR/
(1, -GR)'・・・・・・・・・・・・(2)G=
exp(((]-α)L)・・・・・・・・・・・・
...(3)a=Q/<14-PI/p>...
・・・・・・・・・・・・・・・(4) OS φ=δ−(b/2)g. (P,/P,)/(1+P/
P) ・・・・・・・・・・・・・・・(5)S Here, η is the light injection efficiency into the active layer 2 of the semiconductor laser 1, and ■ is the transmission of the male surface of the semiconductor laser 1. R is the reflectance of the male surface of the semiconductor laser 1, Q is the saturation amplification gain coefficient, and α is the loss coefficient. is the small signal gain coefficient, L is the semiconductor laser 1
P8 is the saturation power of the laser output light, φ is the amount of phase change of the light per pass of the light in the active layer 2 of the semiconductor laser 1, δ is the initial detuning, and the coefficient is the saturation power of the laser output light. The ratio of the rate of change of the refractive index and gain coefficient of the active layer 2 with respect to the density of carriers injected into the active layer 2 (AI Ga As /G
-0, 5 to -6, 2) for an aAS semiconductor laser.

As a result of various experiments, the present inventors have determined that in the optical amplification method using the principle semiconductor laser shown in FIG. 1, the relationship between the power P of the laser output light S2 and the power P of the laser input light S1 is , the input optical power of the S-shaped laser as shown in FIG. It was confirmed that the laser has a pair of laser output optical power characteristics.

However, in Fig. 2, the small signal gain coefficient g is 28 cm-1,
The loss coefficient is 10 cm-', the laser length is 500 μm, the open plane reflectance R is 0.35, and the initial separation δ is 2°75 ra.
This is the characteristic when d.

Furthermore, as a result of various experiments, the present inventors have determined that the power P of the laser output light S2 with respect to the power P of the laser input light S1 in the optical amplification method using the principle semiconductor laser shown in FIG. The relationship is as follows with initial detuning δ, which is another parameter of the power gain G mentioned above, as a parameter:
It has been confirmed that the laser has the J: Ear, S-shaped laser input optical power vs. laser output optical power characteristics shown in FIG.

However, in FIG. 3, the small signal gain coefficient g. is 28cm-1
, loss factor 6\1Qcm-', laser length 50C1m,
This is the characteristic when the open-face reflectance R is 0.35.

Therefore, in the optical amplification method using the principle semiconductor laser shown in FIG.
As an optical amplification method according to the present invention, we have proposed a method of performing nonlinear amplification by utilizing the characteristics of the S-shaped laser input light power of a semiconductor laser and the output light power characteristic.

As described above, the optical amplification method using a semiconductor laser according to the present invention has been clarified.

According to the optical amplification method using a semiconductor laser according to the present invention, it is possible to obtain an optical pulse waveform shaping function, an optical logic gate function, an optical memory function, etc.
It has the following characteristics.

That is, the laser input light S1 has a power waveform that exceeds the point at which the laser input light power takes a maximum value when viewed on the S-shaped laser input light power versus laser output light power characteristic curve shown in FIGS. 2 and 3. If so, the laser input light S
1 can be nonlinearly amplified by shaping the optical pulse waveform.

Further, it is assumed that there are a plurality of laser input lights S1, for example, two, and the sum of the powers of those two laser input lights is the laser input light power vs. laser output light power characteristic curve. If the optical power has a value exceeding the maximum value, the laser input light S1 can be nonlinearly amplified in the form of a logic gate.

Further, the laser input light S1 is between the maximum value of the laser input light power and the intermediate value between the maximum value and the minimum value of the laser input light on the laser input light power versus laser output light power characteristic curve. Laser input light that takes a power of positive polarity that is greater than the absolute value of the difference, and laser input light that takes power of negative polarity that is more than the absolute value of the difference between the above-mentioned intermediate value and the minimum value of the laser input light power. Assume that these two laser input lights are selectively applied to the active layer 2 of the semiconductor laser 1 while the bias light having the above-mentioned intermediate power is injected into the active layer 2 of the semiconductor laser 1. If the laser input light S1 is injected into the laser input light S1, the laser input light having the above-mentioned positive polarity and negative polarity powers will be expressed as "1" and rO
It can be nonlinearly amplified and stored in memory in a form corresponding to J.

Furthermore, in the case of the optical amplification method using the semiconductor laser according to the present invention, as is clear from the characteristics shown in FIG. As the power of the laser input light S1 approaches , the laser input light S1 can be nonlinearly amplified with a small power of the laser input light S1.

Furthermore, in the case of the optical amplification method using the semiconductor laser according to the present invention described above, the carrier lifetime τ in the active layer 2 of the semiconductor laser can be set to several ns, while the power P of the laser input light S1 is 1On+W
, if η is 0.5, it will be 1 mW, so P+x
It has the characteristic that nonlinear amplification can be performed with an extremely small switching energy represented by τ of several PJ.

[Brief explanation of drawings]

FIG. 1 is a route diagram showing a principle optical amplification method using a semiconductor laser, which is used to explain the optical amplification method using a semiconductor laser according to the present invention. FIGS. 2 and 3 are diagrams showing the S-shaped laser input optical power vs. laser output optical power characteristics of a semiconductor laser, for explaining the optical amplification method using the semiconductor laser according to the present invention. 1... Semiconductor laser S1... Laser input light 2.
・・・・・・・・・・・・・・・Active layer S2...
......Laser output light 3...
・・・・・・・・・・・・Power supply applicant Nippon Telegraph and Telephone Public Corporation @1 Figure

Claims (1)

[Claims] Using a semiconductor laser, injecting laser input light into its active layer while injecting a current below the oscillation threshold,
Amplified laser output light of the laser input light is output from the active layer, and the laser input light is 1i141ii
In the optical amplification method using a semiconductor laser, the laser input light is nonlinearly amplified using the S-shaped laser input light power pair laser output light power characteristics of the semiconductor laser. Law.