JPH10256671A - Gain measuring method, gain measuring specimen and gain measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply obtain intensity dependency of gain and gain spectrum, in a non-destructive manner, by obtaining the gain from the ratio of the transmission light intensity of a part where gain medium exists to the transmission light intensity of the part where gain medium does not exist. SOLUTION: A measurement light Lprobe and a pumping light Lpump are mixed by, e.g. an optical combiner 13. A specimen 30 is irradiated with the combined light L, by using, e.g. a tip sphere fiber 14. Out of a transmitted light Lt, a transmitted measurement light which has passed through a spectroscope 16 is only selected, and is detected with a light intensity measuring apparatus 17. The tip sphere fiber 14, the spectroscope 16 and the measuring apparatus 17 are not moved but only the specimen 30 is moved. Intensity of the transmitted measurement light Ltprobe1 of the part where an active layer 33 exists, and intensity of the transmitted measurement light Ltprobe2 of the part where the active layer 33 does not exist are measured. The logarithm (base: natural logarithm (e)) of the ratio of Ltprobe1 to Ltprobe2 is obtained. Thereby the real gain of the active layer 33 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gain measuring method, a gain measuring sample, and a gain measuring device, and more particularly, to a method of measuring a surface direction gain of an active layer used for a surface emitting laser, a sample used for measurement, and a measuring device therefor. About.

[0002]

2. Description of the Related Art Generally known as a method for measuring gain is the Journal of Applied Physics (USA), 27 [8] (19)
73) The Hakki-Paoli method disclosed in Basil W. Hakki, Thomas L. Paoli, p4113-4119. In this method, a sample is processed into an edge-emitting laser structure, and a gain medium is excited by current injection to check a gain.

[0003]

However, the above H
In the akki-Paoli method, since a so-called edge-emitting laser structure is used, it is necessary to process a sample into a laser structure (for example, polishing, cleaving, forming an electrode, etc.). Further, since the gain medium is excited by current injection, laser oscillation occurs when the excitation is increased. For this reason, it is not possible to measure a further gain, and it has been difficult to measure up to the saturation level of the gain.

[0004]

SUMMARY OF THE INVENTION The present invention is a gain measuring method, a gain measuring sample, and a gain measuring device which have been made to solve the above-mentioned problems. That is, the gain measuring method irradiates a sample including the gain medium with a beam of measurement light having a wavelength at which the gain of the gain medium is to be measured and an excitation light having energy higher than the transition energy of the gain medium, and irradiates the sample with the light. In the gain measuring method for obtaining the gain of the gain medium from the transmitted light intensity, the gain medium is formed on the sample surface, and at least a part of the gain medium is removed over an area wider than one irradiation area of the beam. Use a sample. Then, the sample is irradiated with light obtained by combining the excitation light and the measurement light, and only the transmitted light intensity of the measurement light among the light transmitted through the sample is measured. The measurement of the transmitted light intensity of the measurement light is performed in a portion where the gain medium is present and in a portion where the gain medium is not present, and the transmitted light intensity of the measurement light in the portion where the gain medium is present, The gain is obtained from the ratio with the transmitted light intensity in the portion where the gain medium does not exist.

In the above gain measurement method, since light excitation is used as a means for exciting the gain medium, it is not necessary to inject a current into the gain medium. Therefore, there is no need to fabricate the structure of the laser device. Therefore, the gain can be easily measured nondestructively at the wafer level, and a laser device can be manufactured using the same wafer after the gain measurement. Another advantage is that the gain can be measured up to the saturation level.

The gain measurement sample has a portion where a gain medium exists and a portion where no gain medium exists on the same sample surface.

In the above gain measurement sample, since a portion where the gain medium exists and a portion where the gain medium does not exist on the same sample surface, the light for measuring the gain is moved by moving the gain measurement sample. It becomes easier to irradiate the part where the gain medium exists and the part where the gain medium does not exist.

The gain measuring device irradiates a sample containing a gain medium with a beam of measurement light and excitation light, and obtains the gain of the gain medium from the transmitted light intensity of the light applied to the sample. That is, the gain measurement device includes a measurement light source that oscillates measurement light having a wavelength at which the gain of the gain medium is to be measured,
An excitation light source that oscillates excitation light having energy higher than the transition energy of the gain medium; and an optical multiplexer that combines the measurement light oscillated from the measurement light source and the excitation light oscillated from the excitation light source to emit multiplexed light. Is provided. Further, a sample moving means for fixing the sample and moving a portion of the sample where the gain medium exists and a portion where the gain medium does not exist on the optical path of the multiplexed light emitted from the optical multiplexer is provided. ing. Further, a spectroscope for dispersing the measurement light from the combined light transmitted through the sample is provided, and a light intensity measurement device for measuring the intensity of the measurement light separated by the spectroscope is provided.

In the above gain measuring device, since the excitation light source oscillating the excitation light having energy higher than the transition energy of the gain medium is provided, the gain medium is excited by the excitation light oscillated from the excitation light source. Therefore, it is not necessary to inject a current into the gain medium. Therefore, there is no need to fabricate a laser structure on the sample. Therefore, the gain can be easily measured nondestructively at the wafer level, and a laser can be manufactured using the wafer after the gain measurement. It also has the advantage that the gain can be measured up to the saturation level.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the gain measuring method of the present invention will be described below.

First, a gain measurement sample (hereinafter, referred to as a sample)
Will be described with reference to the schematic configuration sectional view of FIG. Here, an indium phosphide (InP) -based semiconductor structure is shown as an example, but the same can be said for other semiconductor material-based samples such as gallium arsenide (GaAs).

As shown in FIG. 2, on an InP substrate 31, a first InP cladding layer 32 formed by crystal growth using, for example, a MOVPE apparatus, and an active layer 3 of a gain medium.
Third, the second InP cladding layer 34 is sequentially stacked.
The back surface of the InP substrate 31 is mirror-polished to suppress scattering of light (when the substrate is mirror-polished from the beginning, there is no need to perform mirror polishing).

In the second InP cladding layer 34 and the active layer 33, a hole (or groove) 35 having the upper surface of the first InP cladding layer 32 as a bottom is formed. This hole 35 is formed by wet etching of the upper second InP cladding layer 34 and the active layer 33 using, for example, a usual lithography technique and etching technique [wet etching of InP: hydrochloric acid (HCl), wet etching of InGaAsP: sulfuric acid. (H ₂ SO ₄ ) + aqueous hydrogen peroxide (H ₂ O ₂ + H ₂ O)]. The removal area is, for example, at least one irradiation area of the beam diameter (for example, 20 μm) of the multiplexed light described later, and preferably an area that is about three times or more of one irradiation area of the beam. In this way, the sample 30 in which the active layer 33 is formed on the sample surface excluding at least one irradiation area of the beam, that is, the portion where the active layer 33 exists in the same sample 30 and the portion where the active layer 33 exists. A sample 30 having a non-portion is formed.

Thereafter, coating films 36 and 37 for removing the effect of multiple reflection on both surfaces (front and back surfaces) of the sample 30 are formed on both surfaces of the sample 30 with a thickness λ / (4n) (where λ: Measurement wavelength, n: the refractive index of the coating film). The coating films 36 and 37 are formed of, for example, aluminum oxide (Al ₂ O ₃ ).

In the sample 30 for measuring the gain,
Since there is a portion where the gain medium exists and a portion where the gain medium does not exist on the same sample surface, the light for measuring the gain can be transmitted only by moving the sample 30 to the active layer which is the gain medium. It becomes easy to irradiate the part where the active layer 33 does not exist and the part where the active layer 33 does not exist (removed part 35).

Next, an embodiment of the present invention will be described with reference to FIG. In FIG.
(1) shows the measurement of the portion where the gain medium exists,
(2) shows a measurement of a portion where no gain medium exists.

As shown in FIGS. 1 (1) and 1 (2), a measurement light L composed of a laser light having a wavelength whose gain is to be measured.
_{The pump} and the pumping light L _pump composed of a laser beam having energy higher than the transition energy of the gain medium are mixed by, for example, an optical multiplexer 13, and the combined light L
Is squeezed to a diameter of 10 μm to 20 μm to irradiate the sample 30 described with reference to FIG. At that time, for example, the light emitting end of the spherical fiber 14 is brought close to the sample 30 to about 15 μm. The measurement light L _probe and the excitation light L _pump
For example, when the gain band of the active layer 33 is near 1.55 μm, the wavelength of the measurement light L _probe is 1.55 μm, and the wavelength of the pump light L _pump is 1.48 μm.

From the transmitted light Lt transmitted through the sample 30, only the measuring light (transmitted measuring light) transmitted by using the spectroscope 16 (or a wavelength filter) is selected, and is selected by the light intensity measuring device 17. To detect. The tip fiber 14, the spectroscope 16, and the light intensity measuring device 17 are not moved, and only the sample 30 is moved by a fine movement stage (for example, a micrometer type fine movement stage) (not shown), and the active layer 33 is present. The intensity of each of the transmission measurement lights Lt _probe1 and Lt _{probe2 in} the portion and the portion where the active layer 33 is not present is measured.

The intensity of the measurement light L _probe immediately before entering the sample 30 is I _probe , the intensity of the excitation light L _pump is I _pump ,
Transmission measurement light Lt _probe1 transmitted through the portion where 3 exists
Is I ₁ , and the intensity of the transmission measurement light Lt _{probe 2} transmitted through the portion where the active layer 33 is not present is I ₂ .

As shown in FIG. 1A, the transmission measuring light Lt _probe1 transmitted through the portion where the active layer 33 exists.
Intensity I ₁ of is detected in the form of gain and first in accordance with the intensity I _pump of the excitation light L _pump, the effect of absorption in the InP layer of the second cladding layer 32, 34 together formula (1) You.

[0021]

(Equation 1)

On the other hand, as shown in FIG. 1B, the transmission measurement light L transmitted through the portion where the active layer 33 does not exist.
intensity I ₂ of t _probe2 is first no gain is detected in the form of absorption effect only represented by formula in the InP layer of the second cladding layer 32 (2).

[0023]

(Equation 2)

The ratio of I ₁ to I ₂ is given by the following equation (3).
Can be approximated as follows.

[0025]

(Equation 3)

By taking the logarithm (base: natural logarithm e) of the above equation (3), a net gain of the active layer 33 can be obtained. It is expressed in equation (4).

[0027]

(Equation 4)

As described above, a net gain can be easily obtained from the ratio between I ₁ and I ₂ .

In the above gain measurement method, since light excitation is used as a means for exciting the active layer 33 as a gain medium, there is no need to inject current into the active layer 33. Therefore, there is no need to manufacture a laser device. Therefore, gain can be measured easily and nondestructively at the wafer level,
After the gain measurement, a laser device can be manufactured using the same wafer. Another advantage is that the gain can be measured up to the saturation level. (1) By setting the portion where the active layer 33 is not present to be approximately three times or more the beam diameter of the combined light L, even if the irradiation region of the combined light L is slightly shifted, the irradiated region is applied to the active layer 33. Disappears. Therefore, highly accurate measurement is possible.

Further, the pump intensity dependence of the gain can be obtained by sequentially changing the intensity I _pump of the _pump light L _pump . For example, the measurement light L leave a constant wavelength lambda _probe of _probe, by irradiating the portion where the active layer 33 is present the combined light L by measuring the intensity I ₁ of transmitted measuring light Lt _probe1 at that time, the value Is stored. Next, the portion where the active layer 33 is not present is irradiated with the combined light L to transmit the transmission measurement light L at that time.
measuring the intensity I ₂ of t _probe2, and stores the value. Then, a net gain is obtained from the stored intensities I ₁ and I ₂ . By performing this measurement procedure each time the intensity I _pump of the _pump light L _pump is sequentially changed, the pump intensity dependence of the gain is obtained.

An example of the dependence of the gain on the pumping intensity will be described with reference to FIG. In FIG. 3, the vertical axis represents the gain, and the horizontal axis represents the pump light intensity. As shown in FIG. 3, the excitation light intensity gain G becomes 0, i.e., it is possible to obtain an excitation light intensity I ₀ of the active layer becomes transparent. Further, it is possible to obtain the excitation light intensity (maximum excitation light intensity at which the carrier density becomes saturated) Imax at which the maximum gain Gmax is obtained.

Further, the wavelength dependency (gain spectrum) of the gain by changing the wavelength lambda _probe of the measuring light L _probe also can be determined. For example, the excitation light L _pump intensity I _pump the Leave constant, transmission measurement light Lt at that time by irradiating the multiplexed light L in the portion where the active layer 33 is present _probe1
The intensity I ₁ is measured, and stores that value. Then, the active layer 33 by irradiating the multiplexed light L in a portion does not exist by measuring the intensity I ₂ of the transmitted measuring light Lt _probe2 at that time, and stores that value. Then, a gain (net gain) is obtained from the stored intensities I ₁ and I ₂ . This measurement procedure is referred to as measurement light L
By performing each sequentially changing the wavelength lambda _probe of _probe, the wavelength dependence of the gain is obtained.

An example of the wavelength dependence of the gain, that is, an example of the gain spectrum will be described with reference to FIG. In FIG. 4, the vertical axis indicates the gain, and the gain increases in the direction of the arrow on the vertical axis. On the other hand, the wavelength of the measurement light is shown on the horizontal axis, and the wavelength becomes longer in the direction of the arrow on the horizontal axis. FIG.
As shown in (1), a wavelength profile can be obtained from the gain and the wavelength of the measurement light. In this example, the gain increases as the wavelength of the measurement light increases, and reaches a maximum gain at a certain wavelength. As the wavelength is further increased, the gain decreases. Thus, the gain spectrum is easily obtained.

By obtaining the relationships shown in FIGS. 3 and 4, it is possible to obtain the maximum gain (the excitation light intensity at which the carrier density becomes saturated) which is an important parameter of the active region without actually configuring the laser device. ), The excitation light intensity (carrier density) at which the active layer becomes transparent can be known. This makes it possible to easily optimize the active layer.

Next, an embodiment of the gain measuring apparatus according to the present invention will be described with reference to the schematic configuration diagram of FIG.

As shown in FIG. 5, the gain measuring device 10
The configuration is as follows. A measurement light source 11 for oscillating measurement light L _probe having a wavelength at which the gain of the gain medium is to be measured and an excitation light source 12 for oscillating excitation light L _pump having energy higher than the transition energy of the gain medium are provided. As the measurement light source 11, for example, a wavelength-variable laser oscillator is used as a light source whose wavelength is variable. On the other hand, for the excitation light source 12, for example, a laser oscillation device whose oscillation intensity is changed by an applied current is used.

The more the measurement light source 11 optical coupler 13 for emitting the combined light L multiplexes the pumping light L _pump oscillated from the measurement light L _probe and said excitation light source 12 oscillated from is provided. This optical multiplexer 13 allows measurement light L
It becomes easy to simultaneously emit the _probe and the excitation light L _pump from the same place. Note that the measurement light source 11 outputs the measurement light L
_{In order} to guide the _probe to the optical multiplexer 13, for example, an optical fiber (not shown) may be used. Similarly, an optical fiber (not shown) may be used to guide the _pump light L _pump to the _pump light source 12 to the optical multiplexer 13.

A spherical fiber 14 is connected to the side of the optical multiplexer 13 from which the combined light L is emitted, and the combined light L is emitted from the tip. With the forward spherical fiber 14, the combined light L can be easily collected and irradiated to a desired position.

The sample 30 is fixed on the optical path of the combined light L emitted from the spherical fiber 14, and
The portion where the active layer 33 as the gain medium of the sample 30 exists and the portion where the active layer 33 does not exist are separated by the combined light L.
The sample moving means 15 for moving the sample on the optical path is provided. The sample moving means 15 includes, for example, an xy axis stage (or an xyz axis stage) and a driving means (not shown) for moving the stage in each axis direction. Each stage is provided with a hole (not shown) through which light transmitted through the sample 30 can pass without being blocked. The driving means is composed of, for example, a stepping motor (not shown) capable of moving each stage at a level of μm. Alternatively, a driving unit that is driven manually may be used. By providing such a sample moving means 15, the movement of the sample 30 is facilitated, and as a result, the selection of the measurement position is facilitated.

On the optical path of the transmitted light Lt that has passed through the sample 30, light having a specific wavelength from the transmitted light Lt (here, a transmission component of the measurement light of the transmitted light that has passed through the sample 30). Spectroscope 1 for dispersing transmission measurement light Lt _probe )
6 are provided. The provision of such a spectroscope 16 makes it easy to extract only the wavelength to be measured. Therefore, transmitted light Lt (for example, transmitted light Lt _probe ) for a specific wavelength can be extracted.

Further, the light is separated by the spectroscope 16 and emitted.
Transmitted measurement light Lt_probeOn the optical path of the
Measurement light Lt_probeLight intensity measuring device 17 for measuring the intensity I of light
Is provided. This light intensity measuring device 17 is, for example,
Photoelectric conversion elements such as photodiodes and phototransistors
Consists of children. Such a light intensity measuring device 17
Is provided, the transmission measurement light Lt is provided. _probe
It becomes easy to measure the intensity I.

Further, the signal of the intensity I ₁ of the transmission measurement light Lt _{probe 1} transmitted through the portion where the active layer 33 of the sample 30 is measured by the light intensity measuring device 17 and the sample 3
It receives 0 of the signal intensity I ₂ of the transmitted measuring light Lt _probe2 the active layer 33 is transmitted through the portion that is not present, the computer 21 is provided for obtaining a gain from the ratio of their signal quantity. The computer 21 is, for example, a transmission measurement light Lt.
intensity I ₁ of _probe1, the intensity of the transmitted measuring light Lt _probe2 I ₂
, A calculation unit that calculates a net gain based on the intensities I ₁ and I ₂ stored in the storage unit, and a second storage that stores the calculation result And an output unit for outputting a calculation result.

Further, a controller 22 for indicating the wavelength λ _probe of the measurement light source 11 and the intensity I _pump of the excitation light source 12 and for indicating the moving position of the sample moving means 15 is provided. The controller 22 controls, for example, the oscillation wavelength λ _{probe of the} measurement light L _probe for the measurement light source 11.
Means for sending a signal instructing, for example, means for sending a signal instructing the values of the oscillation intensity of the excitation light L _{pu mp} for the excitation light source 12 (I _pump), the sample 30 for example sample moving means 15 For example, a stepping motor (not shown) which is a driving means of a stage for fixing the sample 30 so that a portion where the active layer 33 is present and a portion where the active layer 33 is not present are sequentially moved on the optical path of the combined light L. ) Is provided with means for sending a signal indicating the amount of movement of the stage.

In the gain measuring device 10, the sample moving means 15 to which the sample 30 is fixed is controlled by the controller 22 so that the sample 3
The part where the active layer 33 is present or the part where the active layer 33 is not present is automatically moved on the optical path of the combined light L.

Here, the relationship between the intensity of the transmission measurement light and the stage position will be described with reference to FIG. In the following description, each component of the gain measuring device is denoted by the reference numeral described in FIG. As shown in FIG. 6, the stage position of the sample moving means 15 when the portion active layer 33 is present on the optical path of the combined beam L located to X _1. At this time, the transmission measurement light Lt _probe1 measured by the light intensity measuring device 17 has the intensity I
Indicates ₁ . Then, the computer 21 stores the stage position X ₁ and the intensity I _{1 in association} with each other. Next, the sample moving means 15
As a result, the portion where the active layer 33 does not exist becomes the combined light L
The sample 30 is moved so as to be on the optical path. At that time, while the portion of the active layer 33 is present on the optical path of the combined beam L is located, the intensity I ₁ becomes transmitted measuring light _{Lt pr} obe1 is received by the optical intensity measurement device 17.

An active layer 33 exists on the optical path of the combined light L.
Move the part that does not exist. Sample moving hand at that time
Set the stage position of stage 15 to X_TwoAnd At this time, the light intensity
Transmission measurement light Lt measured by measuring instrument 17_probe2Is the intensity I_Two
Is shown. And stage position X_TwoAnd strength I_TwoCorrespond
And store it in the computer 21. Further, the sample moving means 15
Therefore, the portion where the active layer 33 does not exist is
The sample 30 is moved so as to be on the optical path. that time,
The portion where the active layer 33 does not exist on the optical path of the combined light L
While located, the intensity I_TwoTransmission measurement light Lt _probe2Is light
The light is received by the intensity measuring device 17.

The portion where the active layer 33 exists on the optical path of the combined light L is located again. The stage position of the sample moving means 15 at that time and X _3. In this case, transmission measurement light Lt was measured by light intensity measuring device 17 _probe1 is intensity I ₁ again. Thereafter, by calculating the ratio between the intensity I ₁ and the intensity I ₂ stored by the computer 21, the net gain can be automatically obtained. In FIG. 6, the portion where the intensity I has a gradient covers both the portion where the active layer 33 exists and the portion where the active layer 33 does not exist because the combined light L has a certain beam diameter. Occurs sometimes. The measurement of the intensities I ₁ and I ₂ may be started from either the portion where the active layer 33 exists or the portion where the active layer 33 does not exist.

The controller 22 completes the measurement at one oscillation intensity of the intensity I of the transmission measurement light Lt _probe in the portion of the sample 30 where the active layer 33 exists and in the portion where the active layer 33 does not exist. that was, for example, it receives from the computer 21, or may be provided with means for performing an instruction to change the oscillation intensity of the excitation light L _{pu mp} (I _pump). By providing such means, it becomes possible to automatically determine the excitation intensity dependency of the gain as described with reference to FIG.

Further, the controller 22 controls the activity of the sample 30.
The portion where the layer 33 exists and the active layer 33 do not exist
Measurement light Lt_probeOne shot of strength I
Completion of measurement at the vibration wavelength
Measuring light L _probeOscillation wavelength (λ
_probe) Means for giving instructions to change
You may. By providing such means,
As described with reference to FIG.
Spectrum) can be automatically obtained.

Normally, in order for the surface emitting laser device to perform laser oscillation, the balance between the mirror reflectance and the gain of the active layer is important. Therefore, a portion where the active layer 33 exists such as the sample 30 and a portion where the active layer 33 does not exist are separately formed on the substrate on which the surface emitting laser is manufactured, and the gain is measured using the gain measuring device 10. Active layer 33 depending on the measurement method
By measuring the gain of the active layer 33, the gain of the active layer 33 can be known in advance. Therefore, the design of the reflection mirror of the laser device becomes easy. After the crystal growth of the cladding layer and active layer on the substrate, the gain of the active layer is measured at the wafer level as described above, and the reflectance required for laser oscillation is designed from the measured value of the gain. By manufacturing the device, a laser device can be manufactured under conditions most suitable for the wafer.

[0051]

As described above, according to the gain measuring method of the present invention, a part of the gain medium is removed, and the pump light is changed to the part where the gain medium exists and the part where the gain medium does not exist. Since the gain is measured by irradiating the combined light of the measurement light, the net gain can be obtained from the ratio of the transmitted light transmitted through the two portions. Thereby, the intensity dependence of the gain and the gain spectrum can be easily obtained nondestructively. Also, since the gain medium is excited by optical excitation,
There is no need to inject current into the gain medium, so there is no need to fabricate a laser device structure. Therefore, the gain can be easily measured at the wafer level and nondestructively, and the laser device can be manufactured using the wafer after the gain measurement. Further, it is possible to measure the gain up to the saturation level.

According to the gain measurement sample of the present invention, since the portion where the gain medium exists and the portion where the gain medium does not exist exist on the same sample surface, by moving the gain measurement sample, Light for measuring the gain is easily irradiated to the portion where the gain medium exists and the portion where the gain medium does not exist.

According to the gain measuring apparatus of the present invention, since the excitation light source that oscillates the excitation light having energy higher than the transition energy of the gain medium is provided, the gain medium is excited by the excitation light oscillated from the excitation light source. can do. Further, there is provided a computer for calculating the gain from the intensity of transmitted light transmitted through the portion where the gain medium exists and the portion where the gain medium does not exist. The sample moving means, the wavelength of the measurement light source, the intensity of the excitation light source, and the like are provided. Is provided, the gain spectrum can be measured, and the pump light intensity dependence of the gain can be automatically obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a gain measuring method according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of the configuration of a gain measurement sample of the present invention.

FIG. 3 is a diagram showing the relationship between gain and pump light intensity.

FIG. 4 shows the relationship between gain and measurement light wavelength (gain spectrum).
FIG.

FIG. 5 is a schematic configuration diagram of an embodiment according to a gain measurement device of the present invention.

FIG. 6 is an explanatory diagram of an intensity I of transmission measurement light at a measurement position X.

[Explanation of symbols]

30 Sample 33 Active layer L _Combined light L _probe measurement light L _pump excitation light Lt _probe1 transmission measurement light (part where active layer is present) Lt _probe2 transmission measurement light (part where no active layer is present)

Claims (8)

[Claims] 1. A sample including a gain medium is irradiated with a beam of measurement light having a wavelength at which the gain of the gain medium is to be measured and excitation light having energy higher than the transition energy of the gain medium. In a gain measuring method for obtaining a gain of the gain medium from light intensity, a sample in which a gain medium is formed on a sample surface and at least a part of the gain medium is removed over an area wider than one irradiation area of the beam. When irradiating the sample with light obtained by combining the excitation light and the measurement light, of the light transmitted through the sample, only the transmitted light intensity of the measurement light is measured, and the transmission of the measurement light is performed. The measurement of the light intensity is performed in a portion where the gain medium is present and in a portion where the gain medium is not present, and transmission of the measurement light transmitted through the portion where the gain medium is present. Strength and gain measurement method characterized by determining the gain of the gain medium from the ratio of the transmitted light intensity of the measuring beam transmitted through the portion where the gain medium is not present. 2. The gain measuring method according to claim 1, wherein the pump light intensity dependence of the gain is obtained by changing the intensity of the pump light. 3. The gain measurement method according to claim 1, wherein the wavelength dependence of the gain is obtained by changing a wavelength of the measurement light. 4. A gain measurement sample having a portion where a gain medium exists and a portion where no gain medium exists on the same sample surface. 5. A gain measuring apparatus for irradiating a sample containing a gain medium with a beam of measurement light and excitation light and obtaining a gain of the gain medium from a transmitted light intensity of the light applied to the sample, wherein the gain of the gain medium is A measurement light source that oscillates measurement light having a wavelength to be measured, an excitation light source that oscillates excitation light having energy higher than the transition energy of the gain medium, a measurement light that oscillates from the measurement light source, and an oscillation that oscillates from the excitation light source An optical multiplexer that multiplexes the excitation light and emits multiplexed light, and a section where the sample is fixed and a portion where the gain medium of the sample exists in the optical path of the multiplexed light emitted from the optical multiplexer. A sample moving means for moving a portion where no gain medium is present, a spectroscope for splitting the measurement light from the combined light transmitted through the sample, and a measurement light split by the spectroscope And a light intensity measuring device for measuring the intensity of the light. 6. The gain measuring apparatus according to claim 5, wherein the transmitted light intensity of the measurement light transmitted through the portion of the sample where the gain medium exists, measured by the light intensity measuring device, and the gain medium of the sample. A gain measuring device comprising a calculator for calculating a gain from a ratio of transmitted light intensity of measurement light transmitted through a portion where no light exists. 7. The gain measuring device according to claim 5, wherein the measuring light source is a variable wavelength light source. 8. The gain measuring apparatus according to claim 7, further comprising a controller for instructing a wavelength of the measurement light source and an emission intensity of the excitation light source, and instructing a moving position of the sample moving unit. Gain measuring device.