JPH07333560A - Method for reducing polarization dependency loss and optical element module reducing polarization dependency loss - Google Patents

Abstract

PURPOSE:To realize an optical element module with less polarization dependency loss fluctuation in which the polarization dependency loss fluctuation for the optical element module as a whole is equal to the value obtained by reducing the polarization dependency transmissivity fluctuation from the polarization dependency diffraction efficiency fluctuation. CONSTITUTION:This optical modulator is provided with a function modulating a beam propagating from an incident beam 27 to a primary diffracted light beam 28 by a modulation element 25. Then, a glass plate 11 is arranged at a prescribed angle in the advancing direction of the incident beam 27. Since anisotropy is provided in an acoustooptical medium 21 in a refractive index (n), the diffraction efficiency etap when the incident beam 27 is a horizontal polarization becomes lower than the diffraction efficiency etas when the incident beam 27 is a vertical polarization, and the polarization dependency diffraction efficiency fluctuation DELTAeta occurs. On the other hand, the glass plate 11 is provided with the polarization dependency transmissivity fluctuation DELTAT with a trend opposite to the polarization dependency diffraction efficiency fluctuation DELTAetaof the acoustooptical medium 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reduction of polarization dependent loss in an optical element module such as an acoustooptic element module.

[0002]

2. Description of the Related Art Diffraction phenomenon of light by sound waves (acousto-optic effect)
Can be used to configure an optical modulator, an optical polarizer, an optical filter, etc. (hereinafter collectively referred to as acousto-optic device module). These are used, for example, in optical communication devices, and are described in "Basics of Optoelectronics", AMNON YARIV
Written by Tada and Kamiya, Maruzen, Chapter 12, pp. 319-334 ".

An optical modulator using an acousto-optic device module will be described below with reference to the configuration diagram of FIG.

This optical modulator is composed of an acousto-optic medium 21, a transducer 22, a sound absorbing material 23, an oscillator 24 with an AM modulation function, and a modulation element 25, and converts the incident light 27 into light that propagates to the first-order diffracted light 28. On the other hand, the modulator 25 has a function of performing modulation.

A digital or analog baseband modulation signal applied from the modulator 25 is input to the oscillator 24 with an AM modulation function. This oscillator with AM modulation function 24
The output from is a carrier wave of a predetermined frequency f (for example, 120 MHz) that is AM-modulated, and is transmitted to the transducer 22. Then, from this transducer 22, an ultrasonic traveling wave 26 having an intensity corresponding to the intensity of the carrier wave is transmitted by the acousto-optic medium 21 (for example, tellurium dioxide TeO2 and sound velocity v = 4260 m /
It is configured to propagate in the sound absorbing material 23 in (s).

Incident light 27 (for example, laser light having a wavelength λ of 1550 nm) is incident at an angle of θ (radian) with respect to the vertical direction of the acoustooptic medium 21. Then, the incident light 27 undergoes Bragg diffraction due to the interaction with the supersonic traveling wave 26, and as a result, the first-order diffracted light emitted with the angle changed by 2θ is changed.
Get 28.

The incident angle θ is "wavelength λ of incident light 27", "frequency of carrier wave f", and "speed of sound v in acousto-optic medium 21".
And has a relationship of 2θ = λ · f / v.

Here, the electric field strength I of the input incident light 27
The ratio of i to the electric field intensity Ir of the first-order diffracted light 28, that is, Ir / Ii is called the diffraction efficiency η and is expressed by the following equation (1).

[0009]

[Equation 1]

In the equation (1), the acousto-optic medium 21 has a refractive index n, a photoelastic constant P, a density ρ, and an ultrasonic traveling wave 26.
Is L, the height of the ultrasonic traveling wave is H, and the energy is Pa.
It is represented by.

As expressed by the equation (1), the diffraction efficiency η
Depends on the intensity Pa of the ultrasonic traveling wave 26. In other words, the diffraction efficiency η depends on the baseband modulation signal input to the modulation element 25.

[0012]

However, in the acoustooptic device having the above structure, the acoustic device itself such as TeO ₂ has a refractive index n.
Has anisotropy, the diffraction efficiency ηp when the incident light is horizontally polarized is about 20% (= 1 dB) lower than the diffraction efficiency ηs when the incident light is vertically polarized. There is.

For example, when this acousto-optic device module is inserted into the optical signal path as an optical modulator, the polarization dependent loss is 1 dB, and as a result, the fluctuation of the polarization causes the disturbance of the optical power of 1 dB. Will come.

[0014]

In order to solve the above-mentioned problems, the method of reducing the polarization dependent loss of the present invention uses a glass plate having the polarization dependence of the transmittance of the incident light as the incident light. It is arranged so as to be inclined, and the incident light transmitted through the glass plate is arranged to enter the optical element having a polarization dependence opposite to the polarization dependence of the glass plate with respect to the incident light. With such a configuration, the polarization dependent transmittance fluctuation of the glass plate is reduced from the polarization dependent loss fluctuation of the optical element.

Alternatively, a glass plate having a polarization dependency on the transmittance of incident light is arranged with an inclination with respect to the incident light,
It is arranged so that the polarization plane of this incident light transmitted through the glass plate is rotated by 90 degrees and is incident on the optical element having the same polarization dependence as that of the glass plate with respect to the incident light.
With such a configuration, the polarization dependent transmittance fluctuation of the glass plate is reduced from the polarization dependent loss fluctuation of the optical element.

Alternatively, the optical element module according to the present invention, which has reduced polarization dependent loss, includes a glass plate, which is arranged with an inclination with respect to the incident light, and which has polarization dependency on the transmittance of the incident light, and an incident light. On the other hand, it has a polarization dependence opposite to the polarization dependence of the glass plate and is composed of an optical element on which the incident light transmitted through the glass plate enters.

Alternatively, a glass plate having a polarization dependency on the transmittance of the incident light, which is arranged with an inclination with respect to the incident light, and a polarization having the same tendency as the polarization dependency of the glass plate on the incident light. And an optical element which has dependency and in which the plane of polarization of the incident light transmitted through the glass plate is rotated by 90 degrees and is incident.

[0018]

[Function] The polarization-dependent loss compensating glass plate has the polarization dependence that the transmittance differs depending on whether the incident light is vertical polarization or horizontal polarization. Since it is arranged so as to have a tendency opposite to the polarization dependence of the optical element,
The polarization-dependent loss fluctuation of the entire optical element module is a value obtained by reducing the polarization-dependent transmittance fluctuation of the glass plate from the polarization-dependent diffraction efficiency fluctuation of the optical element.

[0019]

1 is a block diagram showing the structure of an optical modulator using an acousto-optic device module according to a first embodiment of the present invention.

This optical modulator comprises, as shown in FIG. 1, a polarization-dependent loss compensating glass plate 11, an acousto-optic medium 21, a transducer 22, a sound absorbing material 23, an oscillator 24 with an AM modulation function, and a modulating element 25. It is configured. Then, by utilizing the fact that the fluctuation of the periodic refractive index appears in the medium when the ultrasonic wave propagates through the medium transparent to the light, the light propagating from the incident light 27 to the first-order diffracted light 28 is It has a function of performing modulation by the modulation element 25 and can be applied to an optical modulator such as an optical communication device or an optical-related measuring instrument.

The digital or analog baseband modulation signal applied from the modulator 25 is input to the AM modulator oscillator 24. This oscillator with AM modulation function 24
The output from is a carrier wave of a predetermined frequency f (for example, 120 MHz) that is AM-modulated, and is transmitted to the transducer 22. From this transducer 22, an ultrasonic traveling wave 26 having an intensity corresponding to the intensity of the carrier wave is generated.
(For example, tellurium dioxide TeO ₂ and sound velocity v = 4260 m / s) are propagated toward the sound absorbing material 23. Then, at the angle of φ1 (radian) with respect to the traveling direction of the incident light 27, the polarization dependent loss compensating glass plate 11 (hereinafter referred to as glass A plate 11) is arranged.

The incident light 27 is a laser light beam having a wavelength λ of 1550 nm, and after passing through the glass plate 11, the acousto-optic medium 21 has a specific angle θ (radian) from the vertical direction of the acousto-optic medium 21. It is incident.

Generally, when incident light is incident parallel to the wavefront of an ultrasonic traveling wave, diffracted light from each traveling wave layer is output in the same phase in a specific direction. At this time, the in-phase relationship is always established for the first-order sideband components, but the higher-order components cancel each other out of phase relationship, and only the diffracted light of the first-order sideband component appears strongly. The interaction between this incident light and the ultrasonic traveling wave is called Bragg diffraction.

The above-mentioned Bragg diffraction also occurs between the incident light 27 and the ultrasonic traveling wave 26, and the first-order diffracted light 28 emitted with the angle changed by 2θ is obtained. The incident angle θ of the incident light 27 is
27 wavelength λ ″, “carrier frequency f” and “sound velocity v in acousto-optic medium 21”, and 2θ = λ · f /
have a relationship of v.

The diffraction efficiency η at this time depends on the intensity Pa of the ultrasonic traveling wave 26 as shown in the above equation (1). The intensity Pa of the ultrasonic traveling wave 26 is determined by the transducer 22.
Is determined by the output of the oscillator with AM modulation function, which is dependent on the baseband modulation signal input to the modulation element 25. In this way, this optical modulator has a function of modulating the light propagating from the incident light 27 to the first-order diffracted light 28 by the modulator 25.

Next, the operation of the glass plate 11 will be described in detail. The relationship between the glass plate 11 and the incident light 27 is shown in the schematic diagram of FIG.

The incident light 27 travels in the air at an angle of φ1 from the vertical direction with respect to the optically polished surface of the glass plate 11, and is refracted at this optically polished surface at an angle of φ2 (radian) to be reflected by the glass plate 1.
Go straight inside 1. Then, again, the light is refracted at an angle of φ1 on the optically polished surface and emitted into the air. Therefore, the incident light 27 is refracted twice by passing through the glass plate 11.

Generally, the intensity transmittance of the horizontally polarized component of the incident light is Tp, and the intensity transmittance of the vertically polarized component is Ts.
Then, Tp and Ts are expressed by equations (2) and (3), respectively.

[0029]

[Equation 2]

[0030]

[Equation 3]

In the expressions (2) and (3), N represents the number of refraction times, and the glass plate 11 shown in FIG.
If 27 is transparent, then N = 2.

The relationship between φ1 and φ2 is determined by the relationship between the refractive indices of the media according to Snell's law, and is represented by the following equation, where n1 is the refractive index of air and n2 is the refractive index of the glass plate.

Sin φ1 / sin φ2 = n2 / n1 (4) Since n1 and n2 are constants, by determining φ1, Tp and Ts are uniquely determined. Further, when φ1 ≠ 0, there is a relation of Tp> Ts, as is clear from the relation between the equations (2) and (3). The polarization dependent transmittance variation ΔT (dB) due to Tp and Ts is expressed by the following equation.

ΔT = 10Log (Ts / Tp) <0 (5) Next, when the incident light 27 that has passed through the glass plate 11 is incident on the acousto-optic medium 21, the above-mentioned invention solves and uses it. As described in the section of the problem, since the acousto-optic medium 21 has anisotropy in the refractive index n, the diffraction efficiency η when the incident light is vertically polarized light.
The diffraction efficiency ηp when the incident light is horizontally polarized becomes lower than that of s, and polarization-dependent diffraction efficiency fluctuation Δη (dB) occurs. This polarization-dependent diffraction efficiency variation Δη is expressed by the following equation (6).

Δη = 10Log (ηs / ηp)> 0 (6) The total polarization dependent loss variation ΔL (d due to the polarization dependent transmittance variation ΔT and the polarization dependent diffraction efficiency variation Δη
B) is expressed by the following equation (7).

.DELTA.L = .DELTA..eta. +. DELTA.T (7) As is clear from the relationship between the expressions (5) and (6) and the expression (7), the sign of .DELTA.T is opposite to that of .DELTA..eta. The glass plate 11 is arranged in the. As a result, ΔL
Will be reduced from Δη by ΔT.

Based on the above equations (2) to (5), when .phi.1 is .pi. / 4 radians, .DELTA.T is -0.9 dB. When Δη is 1 dB, ΔL is 1 dB in the conventional configuration, whereas ΔL is 1-0.9 in the configuration of this embodiment.
Can be reduced to 0.1 dB.

Further, by properly selecting φ1, optimum design becomes possible.

FIG. 4 shows the calculation results of Tp and Ts when φ1 is changed from 0 radian to 1.5 radian based on the equations (2), (3) and (4). When φ1 exceeds Brewster's angle (about 1 radian), Tp sharply decreases. Therefore, it is desirable to set φ1 to 1.2 radians or less.

On the other hand, the relationship between φ1 and ΔT is expressed by equation (2)
It is expressed by equation (5), and φ1 is changed from 0 radian to 1.5
FIG. 5 shows the calculation results of ΔT when changing to radians. It can be seen that the effect of ΔT remarkably occurs when φ1 is 0.4 radian or more.

As can be seen from the results shown in FIGS. 4 and 5, φ1 is preferably in the range of 0.4 to 1.2 radians.

As described above, according to the first embodiment, the polarization-dependent diffraction efficiency variation Δη of the acousto-optic medium 21.
Since the glass plate 11 having the polarization-dependent transmittance variation ΔT having the opposite tendency to the above is provided, the polarization-dependent loss variation ΔL of this optical modulator is calculated from the polarization-dependent diffraction efficiency variation Δη. It is possible to realize an optical modulator having a small value of the polarization-dependent loss fluctuation, which is a value obtained by reducing the fluctuation of the optical transmittance ΔT.

The present invention is not only applied to an acousto-optic device module, but is also applicable to an interference film filter having polarization dependency on intensity transmittance of incident light, an isolator which is desirable to have no polarization, and the like. It is also applicable to a conventional optical element module.

FIG. 6 is a configuration diagram showing the configuration of an optical element module according to a second embodiment of the present invention. An optical element 12 having polarization dependency on the intensity transmittance of incident light and a polarization dependency. A glass plate 13 that performs the same function as the loss-compensating glass plate 11.
It is applicable to an optical processing unit of an optical communication device and an optical processing unit of a general optical device.

In this optical element module, the incident light 27 is
Before being incident on the optical element 12, it is arranged so that it is incident on the glass plate 13 at an angle of φ1 radian.

The optical element 12 has polarization dependence on the intensity transmittance of the incident light 27. For example, the incident light 27 is vertically polarized as in the acoustooptic medium 21 of the first embodiment. The intensity transmittance ηp when the incident light 27 is horizontally polarized becomes lower than the intensity transmittance ηs at a certain time. As a result, the optical element 12 has a polarization-dependent transmittance variation Δη of the above equation (6).
(DB) occurs.

The glass plate 13 satisfies the expressions (2) to (5) as in the first embodiment. However, N in the equations (2) and (3) is N = 2, and the total polarization dependent loss variation ΔL (dB) is the equation (7). And as a result,
ΔL can be reduced to Δη−ΔT.

As described above, even in the general optical element module such as the second embodiment, when the optical element has the polarization dependency of the intensity transmittance, the glass plate 13 is used.
By providing the above, the total polarization dependent loss fluctuation ΔL is reduced by the polarization dependent transmittance fluctuation ΔT of the glass plate from the polarization dependent transmittance fluctuation Δη of the optical element. An optical element module with small fluctuation can be realized. In the second embodiment, the polarization dependence of the optical element 12 is similar to that of the acousto-optic medium 21 of the first embodiment, and the intensity transmittance η when the incident light 27 is the vertically polarized light.
Intensity transmittance ηp when incident light 27 is horizontally polarized compared to s
However, the intensity dependence ηs when the incident light 27 is vertically polarized is lower than the intensity transmittance ηp when the incident light 27 is horizontally polarized. It is applicable even to an optical element having properties. In that case, the glass plate 15 and the optical element 12 may be arranged so that the polarization planes are rotated 90 degrees and orthogonal to each other.

For example, in FIG. 6, if the horizontal plane of polarization of the glass plate 13 is perpendicular to the plane of the paper and the plane of vertical polarization is perpendicular to this, the optical element 12 should be arranged so that the plane of vertical polarization is the vertical direction of the paper. Good.

By arranging the planes of polarization by rotating 90 degrees and arranging them orthogonally, if the incident light 27 on the glass plate 15 is vertical polarization, it is incident on the optical element 12 as horizontal polarization, If it is a vertically polarized wave, it is incident on the optical element 12 as a horizontally polarized wave. As a result, as in the case where the polarization dependences of the both are opposite to each other as described above, the total polarization dependence loss variation ΔL is calculated from the polarization dependence transmittance variation Δη of the optical element to the polarization dependence of the glass plate. Since the transmittance variation ΔT is reduced, an optical element module with a small polarization dependent loss variation can be realized.

Although the glass plate 15 made of BK7 is used as the polarization dependent loss compensator, the invention is not limited to this, and a dielectric film or the like can be applied as long as it has polarization dependence. . Similarly, in the second embodiment, the polarization dependent loss variation is reduced by using the polarization dependent transmittance variation of the polarization dependent loss compensator, but the polarization of the polarization dependent loss compensator is reduced. It is also possible to reduce the polarization dependent loss fluctuation of the optical element by utilizing the wave dependent reflectance fluctuation.

Next, a third embodiment in which the present invention is applied to a general optical element module as in the second embodiment will be described with reference to FIG.

FIG. 7 is a configuration diagram showing the configuration of an optical element module according to a third embodiment of the present invention. The optical element 12 has a polarization dependence on the intensity transmittance of incident light, and the polarization dependence. It is composed of a first glass plate 13 and a second glass plate 14 which perform the same function as the loss compensating glass plate 11.

In this optical element module, the incident light 27 is
Before being incident on the optical element 12, it is arranged so as to be incident on the first glass plate 13 and the second glass plate 14 at an angle of φ1 radian.

Since the second glass plate 14 operates similarly to the first glass plate 13, the third embodiment also satisfies the formulas (2) to (5) as in the second embodiment. However, since the number of refraction is 4, N in the equations (2) and (3) is N = 4.

As a result, ΔT in the equation (5) is doubled as compared with the second embodiment, and a larger polarization-dependent loss fluctuation reduction effect can be obtained.

That is, when the number of glass plates similar to the glass plate 13 is increased, N in the equations (2) and (3) is N = 2 · M, where M is the total number of glass sheets.

As described above, according to the third embodiment, since M (M is 2 or more) glass plates are provided,
An optical element module having a smaller polarization-dependent loss variation can be realized.

Next, as in the second and third embodiments,
Fourth Embodiment in which the present invention is applied to a general optical element module
The embodiment will be described with reference to FIG.

FIG. 8 is a constitutional view showing the constitution of the optical element module of the fourth embodiment of the present invention, in which the optical element 12 having the polarization dependence on the intensity transmittance of the incident light and the polarization dependence. It is composed of a single-sided antireflection coating glass 15 for loss compensation.

In this optical element module, the incident light 27 is
Before being incident on the optical element 12, it is arranged so as to be incident on the single-sided antireflection coating glass 15 at an angle of φ1 radian.

Since the one-sided antireflection coating glass 15 operates similarly to the glass plate 13, the fourth embodiment also satisfies the expressions (2) to (5) as in the second embodiment. However,
N in the expressions (2) and (3) becomes N = 1. As a result, ΔT in the equation (5) is halved as compared with the second embodiment, but the increase in loss due to the single-sided antireflection coating glass 15 can be extremely reduced.

As described above, according to the fourth embodiment, since the single-sided antireflection coating glass 15 is provided, the polarization-dependent loss fluctuation is reduced and the single-sided antireflection coating glass 15 increases the loss. It is possible to realize an optical element module having an extremely small value.

As is clear from these second to fourth embodiments, according to the present invention, the characteristics and number of glass plates for polarization dependent loss compensation are adjusted according to the magnitude of the polarization dependence of the optical element. Can be freely set, and it becomes possible to optimally reduce the polarization dependent loss fluctuation according to the characteristics of the optical element module.

[0065]

As described above, when the present invention is applied to an optical element module, a glass plate or the like for polarization dependent loss compensation is arranged so as to be opposite to the polarization dependence of the optical element. Therefore, the polarization dependent loss variation ΔL of the optical element module
Is a value obtained by reducing the polarization-dependent transmittance variation ΔT from the polarization-dependent diffraction efficiency variation Δη, and an optical element module with a small polarization-dependent loss variation can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical modulator using an acoustooptic device, which is a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of an optical modulator using a conventional acousto-optic device.

FIG. 3 is a schematic diagram showing a relationship between a glass plate 11 and incident light 27.

FIG. 4 is a diagram showing calculation results of Tp and Ts when φ1 is changed from 0 radian to 1.5 radian.

FIG. 5 is a diagram showing a calculation result of ΔT when φ1 is changed from 0 radian to 1.5 radian.

FIG. 6 is a configuration diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 7 is a configuration diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 8 is a configuration diagram showing a configuration of a fourth exemplary embodiment of the present invention.

[Explanation of symbols]

 11, 13, 14 Glass plate for polarization dependent loss compensation 12 Optical element 15 Single-sided non-reflective coating glass 21 Acousto-optic medium 22 Transducer 23 Sound absorbing material 24 AM modulator oscillator 25 Modulator 26 Ultrasonic traveling wave 27 Incident light 28 First-order diffracted light

Claims (11)

[Claims] 1. A glass plate having a polarization dependence on the transmittance of incident light is arranged with an inclination with respect to the incident light, and the polarization dependence of the glass plate on the incident light is opposite to that of the glass plate. An optical element having a tendency of polarization dependence is arranged so that the incident light transmitted through the glass plate is incident on the optical element, and polarization of the glass plate from polarization dependent loss fluctuation of the optical element. A method for reducing polarization dependent loss, which is characterized by reducing the fluctuation of the dependent transmittance. 2. A glass plate having polarization dependence on the transmittance of incident light is arranged with an inclination with respect to the incident light, and has the same tendency as the polarization dependence of the glass plate on the incident light. An optical element having polarization dependency is arranged so that the polarization plane of the incident light transmitted through the glass plate is incident on the optical element by rotating 90 degrees, and the polarization dependency loss variation of the optical element A polarization-dependent loss reduction method, comprising reducing a polarization-dependent variation of the glass body. 3. The method for reducing polarization dependent loss according to claim 1, wherein a single-sided antireflection coating glass is used as the glass plate. 4. A polarization dependent loss compensator having polarization dependence for incident light is arranged so that the incident light is incident, and the polarization dependent loss compensator for the incident light. An optical element having a polarization dependence opposite to that of the polarization dependence is arranged so that the incident light emitted from the polarization dependence loss compensator enters the optical element, A polarization dependent loss reducing method for reducing the polarization dependent loss of the polarization dependent loss compensator from the polarization dependent loss fluctuation. 5. A polarization dependent loss compensator having polarization dependence for incident light is arranged so that the incident light is incident, and the polarization dependent loss compensator for the incident light. An optical element having a polarization dependence having the same tendency as that of the polarization dependence of 1. is arranged so that the polarization plane of the incident light emitted from the polarization dependence loss compensator is rotated by 90 degrees to enter the optical element. A polarization dependent loss reducing method is characterized by reducing the polarization dependent loss variation of the polarization dependent loss compensator from the polarization dependent loss variation of the optical element. 6. A glass plate, which is arranged with an inclination with respect to the incident light, and has a polarization dependency of the transmittance of the incident light, and a glass plate having a polarization dependency of the glass plate opposite to that of the incident light. An optical element module having a polarization-dependent loss and a polarization-dependent loss reduced, the optical element having the incident light transmitted through the glass plate and incident thereon. 7. A glass plate, which is arranged with an inclination with respect to the incident light and has a polarization dependency in the transmittance of the incident light, and a glass plate having the same tendency as the polarization dependency of the glass plate in the incident light. An optical element module having polarization dependency and having an optical element which is incident when the polarization plane of the incident light transmitted through the glass plate is rotated by 90 degrees and is incident. 8. The optical element module with reduced polarization dependent loss according to claim 6 or 7, wherein a single-sided antireflection coating glass is used as the glass plate having polarization dependent transmission. Optical element module with reduced polarization dependent loss. 9. A polarization-dependent loss compensator having polarization dependence with respect to incident light, and a polarization dependence of the polarization-dependent loss compensator with respect to the incident light. An optical element module having reduced polarization dependent loss, comprising: an optical element that has the polarization dependency of the above tendency and has the incident light exiting from the polarization dependent loss compensator. 10. A polarization dependent loss compensator having polarization dependence on incident light, and the same tendency as the polarization dependence of the polarization dependent loss compensator on the incident light. And a polarization-dependent loss of the incident light exiting the polarization-dependent loss compensator, the polarization plane of which is rotated by 90 degrees and is incident. Optical element module. 11. The optical element module according to claim 7, wherein the glass body or the polarization dependent loss compensator is configured so that the polarization plane of the incident light is rotated by 90 degrees and is incident on the optical element. The polarization plane of the optical element is positioned orthogonal to the polarization plane of, and when the incident light enters the glass body or the polarization dependent loss compensator as horizontal polarization, it is vertically polarized to the optical element. An optical element module, characterized in that when it enters as a wave and enters the glass body or the polarization dependent loss compensator as a vertically polarized wave, it enters the optical element as a horizontally polarized wave.