JP5974775B2 - Reflective liquid crystal phase modulation device, reflective liquid crystal phase modulation system - Google Patents

Description

  The present invention relates to a reflective liquid crystal phase modulation device and a reflective liquid crystal phase modulation system that modulates the phase of light using liquid crystal.

  Conventionally, as this type of liquid crystal phase modulation device, for example, the one described in Patent Document 1 shown below is known. In the apparatus described in Patent Document 1, the phase of outgoing light is modulated with respect to incident light by changing the refractive index of a reflective liquid crystal element that returns outgoing light to the incident light side.

JP 2008-122856 A

  In the conventional liquid crystal phase modulation device, the voltage value applied to the liquid crystal element is changed to generate phase modulation of at least 2π with respect to the wavelength of incident light. For this reason, it is necessary to make the liquid crystal layer have a certain thickness or more. That is, if the thickness of the liquid crystal layer is increased, the phase modulation amount can be set large, and a sufficient phase modulation amount of 0 to 2π can be secured.

  On the other hand, the time until the liquid crystal reaches a certain amount of phase modulation with respect to the change in the voltage applied to the liquid crystal layer is generally proportional to the square of the thickness of the liquid crystal layer. For this reason, when the thickness of the liquid crystal layer is increased in order to ensure a sufficient amount of phase modulation of 0 to 2π, there is a problem that the response speed of the phase modulation becomes slow.

  An object of the present invention is to provide a reflection type liquid crystal phase modulation device and a reflection type liquid crystal phase modulation system in which a phase difference of 0 to 2π is secured and the response speed of phase modulation is increased.

The present invention includes a liquid crystal sandwiched and sealed between a transparent electrode and a reflective electrode, and the liquid crystal includes a first liquid crystal in which a light distribution axis in a major axis direction of the liquid crystal is parallel to a polarization axis of light in a first polarization direction. A second liquid crystal region (12-2) having a region (12-1) and a light distribution axis in the major axis direction of the liquid crystal parallel to the polarization axis of the light in the second polarization direction; 1 the polarization direction of light transmitted through the first liquid crystal region, the light in the first polarization direction transmitted by passing through the first liquid crystal region again reflected by the reflective electrode and emitted from the transparent electrode, the transparent transmits light is the second liquid crystal region in the second polarization direction is incident from the electrode, from the transmitted second said polarization direction of light transmitted through the second liquid crystal region again reflected by the reflective electrode transparent electrode the emitted, the reflective reciprocating light at a first liquid crystal region and the second liquid crystal region crystal phase modulator section ( 2), the incident light is transmitted or reflected and emitted to the first liquid crystal region of the reflective liquid crystal phase modulator, and the light transmitted through the first liquid crystal region of the reflective liquid crystal phase modulator is reflected by the reflective electrode. Then, the first polarized light that is transmitted through the first liquid crystal region again, is incident on the light transmitted through the first liquid crystal region and exits from the reflective liquid crystal phase modulation unit, and is transmitted through or reflected from the incident light. A beam splitter (13-1) transmits light that is transmitted or reflected to the second liquid crystal region of the reflective liquid crystal phase modulator, and passes through the second liquid crystal region of the reflective liquid crystal phase modulator. The light reflected by the reflective electrode is transmitted again through the second liquid crystal region, the light transmitted through the second liquid crystal region and emitted from the reflective liquid crystal phase modulator is incident, and the incident light is transmitted or reflected. A second polarizing beam splitter (13-2) that emits; Provided between the reflective liquid crystal phase modulator and the first polarization beam splitter, and between the reflective liquid crystal phase modulator and the second polarization beam splitter, and the first polarization beam splitter or the second polarization beam. A voltage is transmitted between the transparent electrode and the reflective electrode, and a quarter-wave plate (14) that transmits light reciprocating between the beam splitter and the reflective liquid crystal phase modulator and changes the polarization direction of the light. by supplying the voltage supply unit for applying a predetermined voltage between the liquid crystal (16) and have a incident light emitted from the first polarizing beam splitter to said second polarization beam splitter, the first There is a phase difference between the light in the first polarization direction incident on the liquid crystal region and the light in the first polarization direction emitted from the second liquid crystal region according to the voltage applied to the liquid crystal by the voltage supply unit. resulting be characterized by Rukoto A reflective liquid crystal phase modulation device is provided.

  In the reflection-type liquid crystal phase modulation device according to the present invention, it is preferable that the reflection-type liquid crystal phase modulation apparatus includes a reflecting mirror that reflects the light emitted from the first polarization beam splitter and emits the light to the second polarization beam splitter.

  According to the present invention, in the reflection type liquid crystal phase modulation device, the reflection type liquid crystal phase modulation device preferably has the same polarization direction of incident light and outgoing light.

The present invention includes a plurality of the reflection type liquid crystal phase modulation devices, and the plurality of reflection type liquid crystal phase modulation devices are formed on a common semiconductor substrate, and one of the plurality of reflection type liquid crystal phase modulation devices. The light emitted from the second polarization beam splitter of the phase modulation device is given as incident light to the first polarization beam splitter of any one of the plurality of reflection type liquid crystal phase modulation devices. A reflective liquid crystal phase modulation system is provided.

  According to the reflection type liquid crystal phase modulation device or the reflection type liquid crystal phase modulation system of the present invention, it is possible to improve the response time of phase modulation that gives a phase to the outgoing light with respect to the incident light.

It is a figure which shows the structure of the reflection type liquid crystal phase modulation apparatus which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the optical path of the reflection type liquid crystal phase modulation apparatus which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the structure and optical path of the reflection type liquid crystal phase modulation system which concern on 2nd Embodiment of this invention. It is a figure which shows the structure of the reflection type liquid crystal phase modulation apparatus which concerns on 3rd Embodiment of this invention. It is a figure for demonstrating the optical path of the reflection type liquid crystal phase modulation apparatus which concerns on 3rd Embodiment of this invention. It is a figure for demonstrating the structure and optical path of the reflection type liquid crystal phase modulation system which concern on 4th Embodiment of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
With reference to FIG. 1, a configuration of a reflective liquid crystal phase modulation device according to a first embodiment of the present invention will be described. In FIG. 1, the reflective liquid crystal phase modulator 11 includes a reflective liquid crystal phase modulator 12, a first polarizing beam splitter 13-1, and a second polarizing beam splitter 13-2. The reflective liquid crystal phase modulation device 11 includes a quarter wavelength plate 14, a reflecting mirror 15, and a voltage supply unit 16.

  The reflective liquid crystal phase modulator 12 is composed of a reflective liquid crystal element formed on a single semiconductor substrate, and is a liquid crystal sandwiched and sealed between a transparent electrode (not shown) and a reflective electrode (not shown). (Not shown). The liquid crystal constituting the reflective liquid crystal phase modulation unit 12 includes a first liquid crystal region 12-1 in which the light distribution axis in the major axis direction of the liquid crystal is parallel to the polarization axis of light in the first polarization direction, and the major axis direction of the liquid crystal. A second liquid crystal region 12-2 having a light distribution axis parallel to the polarization axis of the light in the second polarization direction;

  Here, light that is polarized in a specific direction and that is linearly polarized light in the Y-axis direction with respect to the incident direction of the light is S-polarized light, and that is perpendicular to the Y-axis direction with respect to the incident direction. The linearly polarized light is P-polarized light. That is, assuming that the direction perpendicular to the light incident surface is the Z-axis direction, the light in the Y-axis direction is S-polarized light, and the light in the X-axis direction is P-polarized light. In the first and second embodiments, light in the first polarization direction is S-polarized light, and light in the second polarization direction is P-polarized light.

  The reflective liquid crystal phase modulation unit 12 transmits the light in the first polarization direction incident from the transparent electrode through the first liquid crystal region 12-1, reflects the transmitted light in the first polarization direction on the reflection electrode, and then first again. The light passes through the liquid crystal region 12-1 and exits from the transparent electrode. The reflection-type liquid crystal phase modulation unit 12 transmits the light in the second polarization direction incident from the transparent electrode through the second liquid crystal region 12-2, reflects the transmitted light in the second polarization direction by the reflection electrode, and returns to the second state. The light passes through the liquid crystal region 12-2 and is emitted from the transparent electrode.

  In all of the embodiments of the present invention, light entering and exiting the liquid crystal enters and exits substantially perpendicularly to the entrance and exit surface where the light enters and exits the liquid crystal.

  In this way, the light is reciprocated in two different liquid crystal regions, the first liquid crystal region 12-1 and the second liquid crystal region 12-2, and the second liquid crystal region 12 with respect to the light incident on the first liquid crystal region 12-1. A phase difference is given to the light emitted from -2.

  The reflective liquid crystal element used here preferably uses a nematic liquid crystal. Nematic liquid crystals are classified into horizontal alignment (homogeneous alignment) and vertical alignment (homeotropic alignment). In the horizontal alignment, the major axis direction of the liquid crystal molecules is substantially parallel to the transparent electrode surface when no voltage is applied. In the vertical alignment, the major axis direction of the liquid crystal molecules is substantially perpendicular to the transparent electrode surface when no voltage is applied. A liquid crystal material having a positive dielectric anisotropy (Δε> 0) is used for horizontal alignment, and a negative dielectric anisotropy (Δε <0) is used for vertical alignment.

  In addition, the liquid crystal layer of the reflective liquid crystal element in each embodiment of the present invention may be either horizontal alignment or vertical alignment. In the case of vertical alignment, when a voltage is applied to the liquid crystal and the voltage is equal to or higher than a certain voltage value, the major axis direction of the liquid crystal is aligned in one direction along the transparent electrode surface. Accordingly, in the horizontal alignment and the vertical alignment, in the state where no voltage is applied, the direction of the major axis direction of the liquid crystal molecules changes depending on the voltage value applied to the liquid crystal layer. However, the horizontal alignment and the vertical alignment are only the relationship between the magnitude of the voltage value and the direction of the major axis direction of the liquid crystal molecules is reversed, and both have a function of modulating the phase of incident light.

  In the following description of the embodiments, the case where the liquid crystal layer is vertically aligned will be described. Further, the alignment directions of the pair of vertical alignment films are configured to be antiparallel to each other.

  The reflective liquid crystal element is composed of a plurality of pixels, and can independently give an arbitrary voltage value to each pixel. However, the maximum value of the voltage that can be applied to each pixel is determined by the design breakdown voltage of the reflective liquid crystal element and the configuration on the voltage supply side, and is generally about 4 V, for example. With this voltage value as the upper limit, an arbitrary phase difference can be given to the outgoing light with respect to the incident light in each pixel according to the voltage applied to the liquid crystal.

  Here, the phase difference provided by the reflective liquid crystal phase modulator 12 composed of the reflective liquid crystal element will be described.

  The phase difference Δφ1 of the emitted light between when the voltage is applied to the liquid crystal of the reflective liquid crystal element formed on one semiconductor substrate and when it is not applied is expressed by the following equation (1). That is, incident light is transmitted through the liquid crystal to which a predetermined voltage is applied, the transmitted light is reflected by the reflective electrode, is transmitted through the liquid crystal again, is emitted, and the light reciprocates once within the liquid crystal, thereby making the incident light In contrast, a phase difference of Δφ1 is given to the emitted light.

Δφ1 = 2 × Δn × d × 2π / λ (1)
In the above formula (1), the thickness of the liquid crystal is d, the wavelength of incident light is λ, and the refractive index anisotropy when a predetermined voltage is applied to the liquid crystal is Δn. The refractive index anisotropy Δn is (ne−no), where ne is the refractive index in the major axis direction of the liquid crystal and no is the refractive index in the minor axis direction of the liquid crystal.

  In the device of the first embodiment, the liquid crystal of the reflective liquid crystal element formed on one semiconductor substrate is divided into two liquid crystal regions, a first liquid crystal region 12-1 and a second liquid crystal region 12-2. ing. With this configuration, the phase difference Δφ2 when light reciprocates once in the first liquid crystal region 12-1 and reciprocates in the first liquid crystal region 12-1 once in the second liquid crystal region is Is represented by the following equation (2).

Δφ2 = 4 × Δn × d × 2π / λ (2)
The above equation (2) indicates that a phase difference twice as large as that of the above equation (1) is given.

  In this way, when the light is reciprocated in each of the two liquid crystal regions formed on one semiconductor substrate, the thickness d of the liquid crystal is the same as compared with the case where the light reciprocates once in one liquid crystal region. In this case, a double phase difference is obtained. In other words, in order to obtain the same phase difference, it can be seen that the thickness d of the liquid crystal may be ½.

  In the first embodiment, a configuration in which a reflective liquid crystal element is divided into two liquid crystal regions is employed. Therefore, it is sufficient that the phase modulation control in the range of 0 to 2π can be performed on the outgoing light with respect to the incident light at the maximum voltage that can be applied to the liquid crystal. That is, in one liquid crystal region, the thickness d of the liquid crystal is set so that the phase modulation control in the range of 0 to π can be performed on the outgoing light with respect to the incident light at the maximum voltage that can be applied to the liquid crystal.

  The first polarizing beam splitter 13-1 is disposed to face the first liquid crystal region 12-1 of the reflective liquid crystal phase modulation unit 12. The first polarization beam splitter 13-1 has a polarization separation surface 13-1a formed along a rectangular diagonal line.

  The first polarization beam splitter 13-1 transmits or reflects incident light at the polarization separation surface 13-1a. That is, the first polarization beam splitter 13-1 reflects S-polarized incident light of incident light by 90 degrees and transmits P-polarized incident light. The first polarizing beam splitter 13-1 reflects incident light by 90 degrees and emits the incident light to the first liquid crystal region 12-1 of the reflective liquid crystal phase modulation unit 12. The first polarizing beam splitter 13-1 receives the light transmitted through the first liquid crystal region 12-1 and emitted from the reflective liquid crystal phase modulator 12, and transmits the incident light to emit.

  The second polarizing beam splitter 13-2 is disposed to face the second liquid crystal region 12-2 of the reflective liquid crystal phase modulation unit 12. The second polarization beam splitter 13-2 has a polarization separation surface 13-2a formed along a rectangular diagonal line.

  The second polarization beam splitter 13-2 transmits or reflects incident light at the polarization separation surface 13-2a. In other words, the second polarization beam splitter 13-2 reflects S-polarized incident light of incident light by 90 degrees and transmits P-polarized incident light. The second polarization beam splitter 13-2 transmits incident light and emits the incident light to the second liquid crystal region 12-2 of the reflective liquid crystal phase modulation unit 12. The second polarization beam splitter 13-2 receives the light transmitted through the second liquid crystal region 12-2 and emitted from the reflective liquid crystal phase modulation unit 12, and reflects and emits the incident light by 90 degrees.

  The quarter-wave plate 14 is disposed between the reflective liquid crystal phase modulator 12 and the first polarizing beam splitter 13-1 and between the reflective liquid crystal phase modulator 12 and the second polarizing beam splitter 13-2. Is done. The quarter-wave plate 14 has an optical axis inclined at an angle of 45 degrees with respect to incident light. As a result, the quarter-wave plate 14 transmits the light reciprocating between the first polarizing beam splitter 13-1 or the second polarizing beam splitter 13-2 and the reflective liquid crystal phase modulator 12, Change the polarization direction.

  That is, the quarter-wave plate 14 transmits the S-polarized light emitted from the first polarizing beam splitter 13-1, and the transmitted S-polarized light travels back and forth through the first liquid crystal region 12-1. The S-polarized light is changed to P-polarized light. The quarter-wave plate 14 transmits the P-polarized light emitted from the second polarizing beam splitter 13-2, and the transmitted P-polarized light travels back and forth through the second liquid crystal region 12-2. Thus, P-polarized light is changed to S-polarized light.

  The reflecting mirror 15 is composed of a triangular mirror. The reflecting mirror 15 is disposed on the opposite side to the side on which the quarter wavelength plate 14 is disposed with respect to the first polarizing beam splitter 13-1 and the second polarizing beam splitter 13-2. The reflecting mirror 15 is inclined at an angle of 45 degrees with respect to the first polarizing beam splitter 13-1 and the first reflecting surface 15-1 inclined at an angle of 45 degrees with respect to the second polarizing beam splitter 13-2. A second reflecting surface 15-2.

  The reflecting mirror 15 reflects the light emitted from the first polarizing beam splitter 13-1 by 90 degrees on the first reflecting surface 15-1, and then emits the light to the second reflecting surface 15-2. The reflecting mirror 15 reflects the light incident on the second reflecting surface 15-2 by 90 degrees and emits the light to the second polarizing beam splitter 13-2.

  The voltage supply unit 16 supplies a predetermined voltage to be applied to the liquid crystal of the reflective liquid crystal phase modulation unit 12. The voltage supply unit 16 supplies an arbitrary voltage individually and independently to the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the reflective liquid crystal phase modulation unit 12. The voltage supplied to the liquid crystal is set according to the phase difference to be obtained in each liquid crystal region with the maximum applied voltage determined by the breakdown voltage of the liquid crystal as an upper limit. The voltage supplied to the liquid crystal is preferably an alternating voltage in order to suppress liquid crystal burn-in.

  Next, with reference to FIG. 2, the optical path of the light in the reflective liquid crystal phase modulation device 11 and the phase difference given to the incident light will be described.

  S-polarized light 21a, which is linearly polarized light in the Y-axis direction, and becomes incident light of the reflective liquid crystal phase modulation device 11 enters the first polarizing beam splitter 13-1. The light 21 a incident on the first polarization beam splitter 13-1 is reflected by 90 degrees on the polarization separation surface 13-1 a and is incident on the quarter-wave plate 14. The light 21b incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 to become circularly polarized light, and enters the first liquid crystal region 12-1 of the reflective liquid crystal phase modulation unit 12.

  The light 21b incident on the first liquid crystal region 12-1 composed of the liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the first liquid crystal region 12-1 and reflected by the reflective electrode. The light 21c reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  Thus, the light reciprocates in the liquid crystal in the first liquid crystal region 12-1, so that the light 21b incident on the first liquid crystal region 12-1 is compared with the light 21c emitted from the first liquid crystal region 12-1. A phase difference can be given. That is, it becomes possible to give a phase difference in the range of 0 to π to the light 21b according to the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 21c emitted from the first liquid crystal region 12-1 passes through the quarter wavelength plate 14. As a result, the light 21c changes to P-polarized light that is linearly polarized light in the X-axis direction. The light 21c changed to P-polarized light enters the first polarizing beam splitter 13-1. Since the light 21c is P-polarized light, it passes through the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The transmitted light 21c is incident on the first reflecting surface 15-1 of the reflecting mirror 15.

  The light 21c incident on the first reflecting surface 15-1 is reflected by 90 degrees on the first reflecting surface 15-1. The reflected light 21d enters the second reflecting surface 15-2 of the reflecting mirror 15, and is reflected by 90 degrees on the second reflecting surface 15-2. The reflected light 21e is incident on the second polarizing beam splitter 13-2.

  The P-polarized light 21e incident on the second polarization beam splitter 13-2 passes through the polarization separation surface 13-2a and enters the quarter-wave plate 14. The light 21e incident on the quarter-wave plate 14 passes through the quarter-wave plate 14 and becomes circularly polarized light, and enters the second liquid crystal region 12-2 of the reflective liquid crystal phase modulation unit 12.

  The light 21e incident on the second liquid crystal region 12-2 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 21 f reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulator 12. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  Thus, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2, so that the light 21e incident on the second liquid crystal region 12-2 is compared with the light 21f emitted from the second liquid crystal region 12-2. A phase difference can be given. That is, the phase difference in the range of 0 to π can be given to the light 21f with respect to the light 21e in accordance with the voltage applied to the liquid crystal in the second liquid crystal region 12-2.

  The light 21 f emitted from the second liquid crystal region 12-2 is transmitted through the quarter wavelength plate 14. As a result, the light 21f is changed to S-polarized light that is linearly polarized light in the Y-axis direction. The light 21f changed to S-polarized light enters the second polarizing beam splitter 13-2. Since the light 21f is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The reflected light 21 g is emitted from the second polarizing beam splitter 13-2 and becomes emitted light from the reflective liquid crystal phase modulator 11.

  In such an optical path, the phase difference of the light 21g emitted with respect to the light 21a incident on the reflective liquid crystal phase modulator 11 is equal to the phase difference given by the first liquid crystal region 12-1 and the second liquid crystal. This is the sum of the phase differences given in the region 12-2. Thereby, the reflection type liquid crystal phase modulation device 11 can give an arbitrary phase difference in the range of 0 to 2π with respect to the incident light according to the applied voltage of each liquid crystal region.

  Next, the response speed of phase modulation in the reflective liquid crystal phase modulator 11 will be described.

  In the above configuration, the phase modulation response speed was measured with the following measurement requirements. The incident light is, for example, S-polarized light having a wavelength of about 1550 nm. A polarizer that transmits only light at an angle of 45 degrees with respect to the X-axis direction orthogonal to the polarization direction of incident light is disposed on the outgoing light side of the reflective liquid crystal phase modulator 11. A temporal change in the amount of transmitted light when an AC voltage was applied to each liquid crystal region from the voltage supply unit 16 and when it was not applied was measured using a photodetector and an oscilloscope.

  Here, the response speed of the phase modulation is defined as the total of the time required for the light transmission amount to transition from about 10% to about 90% of the maximum value and the time required for the transition from about 90% to about 10%. Further, in order to ensure a phase difference of 0 to 2π, the liquid crystal thickness d in each liquid crystal region was set to about 5 μm. The refractive index anisotropy Δn of the liquid crystal in each liquid crystal region was about 0.12 (measurement wavelength 1550 nm). As a result of measuring the response speed of phase modulation under such measurement requirements, a response speed of about 45 msec was obtained.

  On the other hand, in a conventional configuration in which reflection type liquid crystal phase modulation is formed on one semiconductor substrate and light reciprocates once through the liquid crystal, the response time when obtaining the same phase difference as described above was measured. . As the measurement requirements, the same liquid crystal as that used in the above measurement was used, and the thickness d of the liquid crystal was about 10 μm. As a result of measuring the response speed of the phase modulation with such measurement requirements, the response speed was about 180 msec.

  As can be seen from the above measurement results, in the reflection type liquid crystal phase modulation device 11 according to the first embodiment, a sufficient phase difference of 0 to 2π can be secured and the response time of phase modulation can be improved.

  As described above, according to the first embodiment, two first liquid crystal regions 12-1 and second liquid crystal regions 12-2 having different light distribution axes of liquid crystals are provided on one semiconductor substrate, and the respective liquid crystals are provided. A configuration is adopted in which light travels back and forth in the region. Thereby, a sufficient phase difference of 0 to 2π can be secured without increasing the thickness d of the liquid crystal, and the response time of the phase modulation can be increased.

  In particular, the reflection type liquid crystal phase modulation device 11 according to the first embodiment has a long wavelength of light to be phase-modulated, and is an optical communication that requires a large phase difference with respect to light in a wavelength band of about 1550 nm, for example. It can use suitably for the phase modulation apparatus to be used.

  The light incident on the reflective liquid crystal phase modulation device 11 is substantially perpendicular to the incident surface on which the light enters the liquid crystal. Thereby, the influence of the birefringence dependency of the liquid crystal molecules is suppressed, the contrast ratio of the emitted light is high, and a precise phase pattern can be obtained.

  On the other hand, when the light has an angle with respect to the incident surface of the liquid crystal, it is easily affected by the birefringence dependency of the liquid crystal molecules, the contrast ratio of the emitted light is lowered, and a precise phase pattern is obtained. It becomes impossible.

  Since the device is constituted by one semiconductor substrate, the configuration can be reduced in size. In addition, since a polarizing beam splitter, a quarter wavelength plate, and a reflecting mirror are used, the apparatus can be easily configured.

(Second Embodiment)
With reference to FIG. 3, the configuration of a reflective liquid crystal phase modulation system according to a second embodiment of the present invention will be described. In FIG. 3, the reflective liquid crystal phase modulation system 31 of the second embodiment has the same liquid crystal as the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the first embodiment on a single semiconductor substrate. It is configured by forming four regions. That is, the reflection type liquid crystal phase modulation system 31 forms two reflection type liquid crystal phase modulation devices 11 of the first embodiment on one semiconductor substrate, and uses the emitted light of one device as the incident light of the other device. Composed. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The reflection type liquid crystal phase modulation system 31 includes a first reflection type liquid crystal phase modulation device 31-1 and a second reflection type liquid crystal phase modulation device 31-2 having the same configuration as the reflection type liquid crystal phase modulation device 11 of the first embodiment. Prepare. The first reflection type liquid crystal phase modulation device 31-1 and the second reflection type liquid crystal phase modulation device 31-2 are configured by sharing the reflection type liquid crystal phase modulation unit 12 and the quarter wavelength plate. The light 21g emitted from the first reflective liquid crystal phase modulator 31-1 is given as incident light of the second reflective liquid crystal phase modulator 31-2.

  In the second embodiment, the liquid crystal of the reflective liquid crystal element formed on one semiconductor substrate is divided into four liquid crystal regions. With this configuration, the phase difference Δφ3 when light reciprocates in each of the four liquid crystal regions is expressed by the following equation (3).

Δφ3 = 8 × Δn × d × 2π / λ (3)
The above equation (3) indicates that a phase difference four times that of the equation (1) shown in the first embodiment is given.

  In this way, when the light is reciprocated in each of the four liquid crystal regions formed on one semiconductor substrate, the thickness d of the liquid crystal is the same as compared with the case where the light reciprocates once in one liquid crystal region. In this case, a phase difference of 4 times is obtained. In other words, in order to obtain the same phase difference, the thickness d of the liquid crystal can be ¼.

  Next, with reference to FIG. 3, the optical path of the light in the reflective liquid crystal phase modulation system 31 and the phase difference given to the incident light will be described.

  S-polarized light 21a, which is linearly polarized light in the Y-axis direction, and becomes incident light of the reflective liquid crystal phase modulation system 31 is incident on the first polarizing beam splitter 13-1 of the first reflective liquid crystal phase modulation device 31-1. To do. The light 21 a incident on the first polarization beam splitter 13-1 of the first reflective liquid crystal phase modulator 31-1 is reflected by 90 degrees on the polarization separation surface 13-1 a and is incident on the quarter-wave plate 14. The light 21b incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 and becomes circularly polarized light, and the light 21b of the reflective liquid crystal phase modulator 12 of the first reflective liquid crystal phase modulator 31-1 is used. 1 enters the liquid crystal region 12-1.

  The light 21b incident on the first liquid crystal region 12-1 composed of liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the first liquid crystal region 12-1 of the first reflective liquid crystal phase modulation device 31-1. Reflected by the reflective electrode. The light 21c reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulator 12 of the first reflective liquid crystal phase modulator 31-1. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal of the first liquid crystal region 12-1 of the first reflective liquid crystal phase modulation device 31-1, so that the first light 21b incident on the first liquid crystal region 12-1 is obtained. A phase difference can be given to the light 21c emitted from the liquid crystal region 12-1. That is, the light 21c can be given a phase difference in the range of 0 to π / 2 according to the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 21 c emitted from the first liquid crystal region 12-1 of the first reflective liquid crystal phase modulation device 31-1 is transmitted through the ¼ wavelength plate 14. As a result, the light 21c changes to P-polarized light that is linearly polarized light in the X-axis direction. The light 21c changed to P-polarized light enters the first polarizing beam splitter 13-1 of the first reflective liquid crystal phase modulator 31-1. Since the light 21c is P-polarized light, it passes through the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The transmitted light 21c is incident on the first reflecting surface 15-1 of the reflecting mirror 15 of the first reflective liquid crystal phase modulation device 31-1.

  The light 21c incident on the first reflecting surface 15-1 is reflected by 90 degrees on the first reflecting surface 15-1. The reflected light 21d enters the second reflecting surface 15-2 of the reflecting mirror 15, and is reflected by 90 degrees on the second reflecting surface 15-2. The reflected light 21e is incident on the second polarization beam splitter 13-2 of the first reflective liquid crystal phase modulator 31-1.

  The P-polarized light 21e incident on the second polarization beam splitter 13-2 of the first reflective liquid crystal phase modulator 31-1 passes through the polarization separation surface 13-2a and enters the quarter-wave plate 14. The light 21e incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 and becomes circularly polarized light, and the first light of the reflective liquid crystal phase modulator 12 of the first reflective liquid crystal phase modulator 31-1. 2 is incident on the liquid crystal region 12-2.

  The light 21e incident on the second liquid crystal region 12-2 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 21f reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulator 12 of the first reflective liquid crystal phase modulator 31-1. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2 of the first reflective liquid crystal phase modulation device 31-1, so that the second light is incident on the light 21e incident on the second liquid crystal region 12-2. A phase difference can be given to the light 21f emitted from the liquid crystal region 12-2. That is, the light 21e can be given a phase difference in the range of 0 to π / 2 according to the voltage applied to the liquid crystal in the second liquid crystal region 12-2 with respect to the light 21e.

  The light 21 f emitted from the second liquid crystal region 12-2 of the first reflective liquid crystal phase modulation device 31-1 is transmitted through the ¼ wavelength plate 14. As a result, the light 21f is changed to S-polarized light that is linearly polarized light in the Y-axis direction. The light 21f changed to S-polarized light is incident on the second polarizing beam splitter 13-2 of the first reflective liquid crystal phase modulator 31-1. Since the light 21f is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The reflected light 21g is emitted from the second polarizing beam splitter 13-2 and becomes incident light of the second reflective liquid crystal phase modulation device 31-2.

  S-polarized light 21g, which is incident light of the second reflective liquid crystal phase modulator 31-2, enters the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 31-2. The light 21g incident on the first polarization beam splitter 13-1 of the second reflective liquid crystal phase modulator 31-2 is reflected by the polarization separation surface 13-1a by 90 degrees and is incident on the quarter-wave plate 14. The light 21h incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 to become circularly polarized light, and the second liquid crystal phase modulator 12-2 of the reflective liquid crystal phase modulator 12-2 1 enters the liquid crystal region 12-1.

  The light 21h incident on the first liquid crystal region 12-1 composed of the liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the first liquid crystal region 12-1 of the second reflective liquid crystal phase modulator 31-2. Reflected by the reflective electrode. The light 21i reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulator 12 of the second reflective liquid crystal phase modulator 31-2. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal of the first liquid crystal region 12-1 of the second reflective liquid crystal phase modulation device 31-2, so that the first light 21h incident on the first liquid crystal region 12-1 is first. A phase difference can be given to the light 21i emitted from the liquid crystal region 12-1. That is, the phase difference in the range of 0 to π / 2 can be given to the light 21i with respect to the light 21h according to the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 21 i emitted from the first liquid crystal region 12-1 of the second reflective liquid crystal phase modulation device 31-2 passes through the ¼ wavelength plate 14. Thereby, the light 21i is changed to P-polarized light that is linearly polarized light in the X-axis direction. The light 21i changed to P-polarized light enters the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 31-2. Since the light 21i is P-polarized light, it passes through the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The transmitted light 21i is incident on the first reflecting surface 15-1 of the reflecting mirror 15 of the second reflective liquid crystal phase modulator 31-2.

  The light 21i incident on the first reflecting surface 15-1 is reflected by 90 degrees on the first reflecting surface 15-1. The reflected light 21j enters the second reflecting surface 15-2 of the reflecting mirror 15, and is reflected by 90 degrees on the second reflecting surface 15-2. The reflected light 21k is incident on the second polarization beam splitter 13-2 of the second reflective liquid crystal phase modulator 31-2.

  The P-polarized light 21k incident on the second polarization beam splitter 13-2 of the second reflective liquid crystal phase modulator 31-2 passes through the polarization separation surface 13-2a and enters the quarter-wave plate 14. The light 21k incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 to become circularly polarized light, and the second liquid crystal phase modulator 12-2 of the reflective liquid crystal phase modulator 12-2 2 is incident on the liquid crystal region 12-2.

  The light 21k incident on the second liquid crystal region 12-2 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 21l reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulator 12 of the second reflective liquid crystal phase modulator 31-2. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2 of the second reflective liquid crystal phase modulator 31-2, so that the second light is incident on the light 21k incident on the second liquid crystal region 12-2. A phase difference can be given to the light 21l emitted from the liquid crystal region 12-2. That is, the phase difference in the range of 0 to π / 2 can be given to the light 21l with respect to the light 21k according to the voltage applied to the liquid crystal in the second liquid crystal region 12-2.

  The light 21l emitted from the second liquid crystal region 12-2 of the second reflective liquid crystal phase modulator 31-2 passes through the quarter wavelength plate 14. Thereby, the light 21l is changed to S-polarized light which is linearly polarized light in the Y-axis direction. The light 21l changed to S-polarized light enters the second polarizing beam splitter 13-2 of the second reflective liquid crystal phase modulator 31-2. Since the light 21l is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The reflected light 21m exits from the second polarizing beam splitter 13-2, exits from the second reflective liquid crystal phase modulation device 31-2, and becomes the outgoing light of the reflective liquid crystal phase modulation system 31.

  In such an optical path, the phase difference of the light 21m emitted with respect to the light 21a incident on the reflective liquid crystal phase modulation system 31 is the sum of the phase differences obtained by the respective devices. That is, the phase difference given to the light 21m is equal to the phase difference given by the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the first reflective liquid crystal phase modulation device 31-1, and the second reflective type. This is the sum of the phase differences given by the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the liquid crystal phase modulation device 31-2.

  Accordingly, the reflective liquid crystal phase modulation system 31 can give an arbitrary phase difference to the outgoing light in the range of 0 to 2π with respect to the incident light according to the voltage applied to each liquid crystal region.

  In the configuration of the second embodiment, the liquid crystal thickness d was about 2.5 μm, and the phase modulation response speed was measured with the same measurement requirements as in the first embodiment. As a result of the measurement, a response speed of about 10 msec was obtained.

  As can be seen from the above measurement results, in the reflective liquid crystal phase modulation system 31 in the second embodiment, a sufficient phase difference of 0 to 2π is secured, and the response time of the phase modulation as compared with the previous first embodiment. Can be further speeded up.

  As described above, the reflective liquid crystal phase modulation system 31 of the second embodiment is configured by forming the two reflective liquid crystal phase modulation devices employed in the previous first embodiment on a common semiconductor substrate. As a result, the same effect as in the first embodiment can be obtained. Furthermore, the reflective liquid crystal phase modulation system 31 of the second embodiment can further increase the response speed of the phase modulation as compared with the first embodiment.

  In the second embodiment, the two reflective liquid crystal phase modulators used in the first embodiment are formed on a common semiconductor substrate, but two or more reflective liquid crystal phase modulators are shared. It can also be formed on a semiconductor substrate.

(Third embodiment)
With reference to FIG. 4, the configuration of a reflective liquid crystal phase modulation device according to a third embodiment of the present invention will be described. In the third embodiment, light in the first polarization direction is P-polarized light, and light in the second polarization direction is S-polarized light. Thereby, in the reflection type liquid crystal phase modulation device 11 of the first embodiment, the incident light and the emission light are S-polarized light, whereas the reflection type liquid crystal phase modulation device 41 of the third embodiment The incident light and the outgoing light are P-polarized light.

  In the third embodiment, P-polarized light is used as incident light and outgoing light. Therefore, in FIG. 4, the reflection type liquid crystal phase modulation device 41 is configured by removing the reflecting mirror 15 as compared with the configuration of the reflection type liquid crystal phase modulation device 11 of the first embodiment.

  The rest of the reflective liquid crystal phase modulation device 41 is the same as that of the first embodiment. Thereby, the reflective liquid crystal phase modulation device 41 can give the phase difference expressed by the equation (2) to the P-polarized incident light as in the first embodiment.

  In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  Next, with reference to FIG. 5, the optical path of the light in the reflective liquid crystal phase modulation device 41 and the phase difference given to the incident light will be described.

  P-polarized light 42a which is linearly polarized light in the X-axis direction and becomes incident light of the reflective liquid crystal phase modulation device 41 is incident on the first polarization beam splitter 13-1. The light 42 a incident on the first polarization beam splitter 13-1 passes through the polarization separation surface 13-1 a and enters the quarter wavelength plate 14. The light 42 a incident on the quarter wavelength plate 14 passes through the quarter wavelength plate 14 and becomes circularly polarized light, and enters the first liquid crystal region 12-1 of the reflective liquid crystal phase modulation unit 12.

  The light 42a incident on the first liquid crystal region 12-1 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the first liquid crystal region 12-1 and reflected by the reflective electrode. The light 42a reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  Thus, the light reciprocates in the liquid crystal in the first liquid crystal region 12-1, so that the light 42a incident on the first liquid crystal region 12-1 is compared with the light 42b emitted from the first liquid crystal region 12-1. A phase difference can be given. That is, the phase difference in the range of 0 to π can be given to the light 42b with respect to the light 42a in accordance with the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 42 b emitted from the first liquid crystal region 12-1 is transmitted through the quarter wavelength plate 14. As a result, the light 42b is changed to S-polarized light that is linearly polarized light in the Y-axis direction. The light 42b changed to S-polarized light enters the first polarizing beam splitter 13-1. Since the light 42b is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The reflected light 42c is incident on the second polarization beam splitter 13-2.

  The S-polarized light 42c incident on the second polarization beam splitter 13-2 is reflected by 90 degrees on the polarization separation surface 13-2a, and the reflected light 42d is incident on the quarter-wave plate 14. The light 42d incident on the quarter-wave plate 14 passes through the quarter-wave plate 14 and becomes circularly polarized light, and enters the second liquid crystal region 12-2 of the reflective liquid crystal phase modulation unit 12.

  The light 42d incident on the second liquid crystal region 12-2 composed of liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 42d reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2, so that the light 42d incident on the second liquid crystal region 12-2 is compared with the light 42e emitted from the second liquid crystal region 12-2. A phase difference can be given. That is, the light 42e can be given a phase difference in the range of 0 to π according to the voltage applied to the liquid crystal in the second liquid crystal region 12-2 with respect to the light 42d.

  The light 42e emitted from the second liquid crystal region 12-2 is transmitted through the quarter wavelength plate 14. Thereby, the light 42e is changed to P-polarized light that is linearly polarized light in the X-axis direction. The light 42e changed to P-polarized light enters the second polarizing beam splitter 13-2. Since the light 42e is P-polarized light, it passes through the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The transmitted light 42 e is emitted from the second polarizing beam splitter 13-2 and becomes emitted light from the reflective liquid crystal phase modulation device 41.

  In such an optical path, the phase difference of the light 42e emitted with respect to the light 42a incident on the reflective liquid crystal phase modulator 41 is equal to the phase difference given by the first liquid crystal region 12-1 and the second liquid crystal. This is the sum of the phase differences given in the region 12-2. As a result, the reflective liquid crystal phase modulation device 41 gives an arbitrary phase difference in the range of 0 to 2π to the P-polarized incident light with respect to the P-polarized incident light according to the applied voltage of each liquid crystal region. Can do.

  As described above, in the third embodiment, as in the first embodiment, two first liquid crystal regions 12-1 and second liquid crystal regions having different light distribution axes of liquid crystals on one semiconductor substrate are used. 12-2 is provided, and a configuration in which light is reciprocated in each liquid crystal region is adopted. As a result, the same effects as those of the first embodiment can be obtained with respect to incident light and outgoing light of P-polarized light.

(Fourth embodiment)
With reference to FIG. 6, a configuration of a reflective liquid crystal phase modulation system according to a fourth embodiment of the present invention will be described. In FIG. 6, the reflection type liquid crystal phase modulation system 51 of the fourth embodiment has the same liquid crystal as the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the third embodiment on a single semiconductor substrate. It is configured by forming four regions. That is, the reflection type liquid crystal phase modulation system 51 forms two reflection type liquid crystal phase modulation devices 41 of the third embodiment on one semiconductor substrate, and uses the emitted light of one device as the incident light of the other device. Composed. In FIG. 6, the same components as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.

The reflection type liquid crystal phase modulation system 51 includes a first reflection type liquid crystal phase modulation device 51-1 and a second reflection type liquid crystal phase modulation device 51-2 having the same configuration as the reflection type liquid crystal phase modulation device 41 of the third embodiment. Prepare. The first reflection type liquid crystal phase modulation device 51-1 and the second reflection type liquid crystal phase modulation device 51-2 are configured by sharing the reflection type liquid crystal phase modulation unit 12 and the quarter wavelength plate. The reflective liquid crystal phase modulation system 51 includes a reflective mirror 52.
The reflecting mirror 52 is composed of a triangular mirror. The reflecting mirror 52 is ¼ of the second polarizing beam splitter 13-2 of the first reflective liquid crystal phase modulator 51-1 and the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 51-2. It arrange | positions on the opposite side to the side by which the wave plate 14 is arrange | positioned. The reflecting mirror 52 includes a first reflecting surface 52-1 that is inclined at an angle of 45 degrees with respect to the second polarizing beam splitter 13-2 of the first reflective liquid crystal phase modulator 51-1. The reflecting mirror 52 includes a second reflecting surface 15-2 that is inclined at an angle of 45 degrees with respect to the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 51-2.

  The reflecting mirror 52 reflects the light emitted from the second polarizing beam splitter 13-2 of the first reflective liquid crystal phase modulation device 51-1 by 90 degrees on the first reflecting surface 52-1, and the second reflecting surface 52-. 2 is emitted. The reflecting mirror 52 reflects the light incident on the second reflecting surface 52-2 by 90 degrees on the second reflecting surface 52-2, and the first polarizing beam splitter 13-1 of the second reflecting liquid crystal phase modulator 51-2. To exit.

  In the fourth embodiment, a configuration in which light reciprocates in four liquid crystals formed on one semiconductor substrate is employed. With this configuration, the phase difference Δφ3 when light reciprocates through each of the four liquid crystals is expressed by the following equation (3).

Δφ3 = 8 × Δn × d × 2π / λ (3)
The above equation (3) indicates that a phase difference four times that of the equation (1) shown in the first embodiment is given.

  As described above, when the light d reciprocates in the four liquid crystals formed on one semiconductor substrate, the thickness d of the liquid crystal layer is the same as compared with the case where the light reciprocates once in one liquid crystal. 4 times the phase difference. In other words, in order to obtain the same phase difference, the thickness d of the liquid crystal layer can be ¼.

  Next, with reference to FIG. 6, the optical path of the light in the reflective liquid crystal phase modulation system 51 and the phase difference given to the incident light will be described.

  P-polarized light 42a, which is linearly polarized light in the X-axis direction, becomes incident light of the reflective liquid crystal phase modulation system 51, and enters the first polarizing beam splitter 13-1 of the first reflective liquid crystal phase modulation device 51-1. To do. The light 42 a incident on the first polarization beam splitter 13-1 passes through the polarization separation surface 13-1 a and enters the quarter wavelength plate 14. The light 42a incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 and becomes circularly polarized light, and the light of the reflective liquid crystal phase modulator 12-1 of the first reflective liquid crystal phase modulator 51-1. 1 enters the liquid crystal region 12-1.

  The light 42a incident on the first liquid crystal region 12-1 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the first liquid crystal region 12-1 and reflected by the reflective electrode. The light 42a reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the first liquid crystal region 12-1 of the first reflective liquid crystal phase modulation device 51-1, so that the first light 42a incident on the first liquid crystal region 12-1 is detected. A phase difference can be given to the light 42b emitted from the liquid crystal region 12-1. That is, the phase difference in the range of 0 to π / 2 can be given to the light 42b with respect to the light 42a according to the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 42 b emitted from the first liquid crystal region 12-1 of the first reflective liquid crystal phase modulation device 51-1 passes through the ¼ wavelength plate 14. As a result, the light 42b is changed to S-polarized light that is linearly polarized light in the Y-axis direction. The light 42b changed to S-polarized light enters the first polarizing beam splitter 13-1 of the first reflective liquid crystal phase modulator 51-1. Since the light 42b is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The reflected light 42c is incident on the second polarization beam splitter 13-2 of the first reflective liquid crystal phase modulator 51-1.

  The S-polarized light 42c incident on the second polarization beam splitter 13-2 is reflected by 90 degrees on the polarization separation surface 13-2a, and the reflected light 42d is incident on the quarter-wave plate 14. The light 42d incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 and becomes circularly polarized light, and the second liquid crystal phase modulator 12-1 of the first reflective liquid crystal phase modulator 51-1 has the second light. 2 is incident on the liquid crystal region 12-2.

  The light 42d incident on the second liquid crystal region 12-2 composed of the liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 42d reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2 of the first reflective liquid crystal phase modulator 51-1, so that the second light is incident on the light 42d incident on the second liquid crystal region 12-2. A phase difference can be given to the light 42e emitted from the liquid crystal region 12-2. In other words, the light 42e can be given a phase difference in the range of 0 to π / 2 according to the voltage applied to the liquid crystal in the second liquid crystal region 12-2 with respect to the light 42d.

  The light 42e emitted from the second liquid crystal region 12-2 is transmitted through the quarter wavelength plate 14. Thereby, the light 42e is changed to P-polarized light that is linearly polarized light in the X-axis direction. The light 42e changed to P-polarized light enters the second polarizing beam splitter 13-2 of the first reflective liquid crystal phase modulator 51-1. Since the light 42e is P-polarized light, it passes through the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The transmitted light 42 e is incident on the first reflecting surface 52-1 of the reflecting mirror 52.

  The light 42e incident on the first reflecting surface 52-1 is reflected by 90 degrees on the first reflecting surface 52-1. The reflected light 42f is incident on the second reflecting surface 52-2 of the reflecting mirror 52, and is reflected 90 degrees on the second reflecting surface 52-2. The reflected light 42g is incident on the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 51-2.

  The light 42g incident on the first polarization beam splitter 13-1 passes through the polarization separation surface 13-1a and enters the quarter-wave plate 14. The light 42g incident on the quarter-wave plate 14 is transmitted through the quarter-wave plate 14 and becomes circularly polarized light, and the second liquid crystal phase modulator 12-2 of the second reflective liquid crystal phase modulator 51-2 receives the second light. 1 enters the liquid crystal region 12-1.

  The light 42g incident on the first liquid crystal region 12-1 composed of liquid crystal having an alignment axis parallel to the P-polarized light is transmitted through the first liquid crystal region 12-1 and reflected by the reflective electrode. The light 42g reflected by the reflective electrode passes through the first liquid crystal region 12-1 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the first liquid crystal region 12-1 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  Thereby, the light reciprocates in the liquid crystal of the first liquid crystal region 12-1 of the second reflective liquid crystal phase modulator 51-2, so that the first light 42g incident on the first liquid crystal region 12-1 A phase difference can be given to the light 42h emitted from the liquid crystal region 12-1. That is, the phase difference in the range of 0 to π / 2 can be given to the light 42h with respect to the light 42g according to the voltage applied to the liquid crystal in the first liquid crystal region 12-1.

  The light 42h emitted from the first liquid crystal region 12-1 of the second reflective liquid crystal phase modulation device 51-2 is transmitted through the quarter wavelength plate 14. Thereby, the light 42h is changed to S-polarized light that is linearly polarized light in the Y-axis direction. The light 42h changed to S-polarized light is incident on the first polarizing beam splitter 13-1 of the second reflective liquid crystal phase modulator 51-2. Since the light 42h is S-polarized light, it is reflected by 90 degrees on the polarization separation surface 13-1a of the first polarization beam splitter 13-1. The reflected light 42i is incident on the second polarizing beam splitter 13-2 of the second reflective liquid crystal phase modulator 51-2.

  The S-polarized light 42i incident on the second polarization beam splitter 13-2 is reflected by 90 degrees on the polarization separation surface 13-2a, and the reflected light 42j is incident on the quarter-wave plate 14. The light 42j incident on the quarter-wave plate 14 passes through the quarter-wave plate 14 and becomes circularly polarized light, and the second liquid crystal phase modulator 12-2 of the reflective liquid crystal phase modulator 12-2 2 is incident on the liquid crystal region 12-2.

  The light 42j incident on the second liquid crystal region 12-2 composed of the liquid crystal having an alignment axis parallel to the S-polarized light is transmitted through the second liquid crystal region 12-2 and reflected by the reflective electrode. The light 42j reflected by the reflective electrode passes through the second liquid crystal region 12-2 again and is emitted from the reflective liquid crystal phase modulation unit 12. At this time, a predetermined voltage is applied to the second liquid crystal region 12-2 from the voltage supply unit 16, and the liquid crystal molecules are tilted according to the applied voltage value.

  As a result, the light reciprocates in the liquid crystal in the second liquid crystal region 12-2 of the second reflective liquid crystal phase modulator 51-2, so that the second light is incident on the light 42j incident on the second liquid crystal region 12-2. A phase difference can be given to the light 42k emitted from the liquid crystal region 12-2. That is, the light 42k can be given a phase difference in the range of 0 to π / 2 according to the voltage applied to the liquid crystal in the second liquid crystal region 12-2 with respect to the light 42j.

  The light 42k emitted from the second liquid crystal region 12-2 passes through the quarter-wave plate 14. As a result, the light 42k changes to P-polarized light that is linearly polarized light in the X-axis direction. The light 42k changed to P-polarized light enters the second polarizing beam splitter 13-2 of the second reflective liquid crystal phase modulator 51-2. Since the light 42k is P-polarized light, it passes through the polarization separation surface 13-2a of the second polarization beam splitter 13-2. The transmitted light 42k is emitted from the second polarization beam splitter 13-2 and becomes the outgoing light of the reflective liquid crystal phase modulation system 51.

  In such an optical path, the phase difference from which the emitted light 42k is obtained with respect to the light 42a incident on the reflective liquid crystal phase modulation system 51 is the sum of the phase differences obtained by the respective devices. That is, the phase difference given to the light 42k is equal to the phase difference given by the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the first reflective liquid crystal phase modulation device 51-1, and the second reflective type. This is the sum of the phase differences given by the first liquid crystal region 12-1 and the second liquid crystal region 12-2 of the liquid crystal phase modulation device 51-2. As a result, the reflective liquid crystal phase modulation system 51 gives an arbitrary phase difference in the range of 0 to 2π to the P-polarized incident light with respect to the P-polarized incident light in accordance with the applied voltage of each liquid crystal region. Can do.

  As described above, the reflection type liquid crystal phase modulation system 51 of the fourth embodiment is configured by forming the two reflection type liquid crystal phase modulation devices employed in the previous third embodiment on a common semiconductor substrate. Thereby, the same effect as the third embodiment can be obtained.

  Further, in the fourth embodiment, the liquid crystal constituting each reflective liquid crystal phase modulation unit can obtain the same phase difference with half the thickness as compared to the third embodiment. Thereby, in the fourth embodiment, the response speed of the phase modulation can be further increased as compared with the previous third embodiment.

  In the fourth embodiment, the two reflection type liquid crystal phase modulation devices employed in the previous third embodiment are formed on a common semiconductor substrate. However, two or more reflection type liquid crystal phase modulation devices are commonly used. It can also be formed on a semiconductor substrate.

DESCRIPTION OF SYMBOLS 11, 41 ... Reflection type liquid crystal phase modulation device 12 ... Reflection type liquid crystal phase modulation part 12-1 ... 1st liquid crystal area 12-2 ... 2nd liquid crystal area 13-1 ... 1st polarizing beam splitter 13-1a ... Polarization separation surface 13-2 ... 2nd polarization beam splitter 13-2a ... Polarization separation surface 14 ... 1/4 wavelength plate 15, 52 ... Reflection mirror 15-1, 52-1 ... 1st reflection surface 15-2, 52-2 ... 1st 2 reflective surface 16 ... voltage supply unit 31, 51 ... reflective liquid crystal phase modulation system 31-1, 51-1 ... first reflective liquid crystal phase modulator 31-2, 51-2 ... second reflective liquid crystal phase modulator

Claims (4)

A liquid crystal sandwiched between a transparent electrode and a reflective electrode, the liquid crystal including a first liquid crystal region in which a light distribution axis in a major axis direction of the liquid crystal is parallel to a polarization axis of light in a first polarization direction; comprising a light distribution axis of the long axis direction and the polarization axis parallel to the second liquid crystal region of the light in the second polarization direction of the light in the first polarization direction is incident from the transparent electrode is transmitted through the first liquid crystal region Then, the transmitted light in the first polarization direction is reflected by the reflective electrode, is transmitted again through the first liquid crystal region, is emitted from the transparent electrode, and the light in the second polarization direction incident from the transparent electrode is the second light. The light transmitted through the liquid crystal region, the transmitted light in the second polarization direction is reflected by the reflective electrode, is transmitted through the second liquid crystal region again, and is emitted from the transparent electrode. The first liquid crystal region and the second liquid crystal region A reflective liquid crystal phase modulator that reciprocates the light at
The incident light is transmitted or reflected and emitted to the first liquid crystal region of the reflective liquid crystal phase modulator, and the light transmitted through the first liquid crystal region of the reflective liquid crystal phase modulator is reflected by the reflective electrode and again A first polarizing beam splitter that passes through the first liquid crystal region, enters the light that has passed through the first liquid crystal region and exits from the reflective liquid crystal phase modulator, and transmits or reflects the incident light to exit.
The incident light is transmitted or reflected and emitted to the second liquid crystal region of the reflective liquid crystal phase modulator, and the light transmitted through the second liquid crystal region of the reflective liquid crystal phase modulator is reflected by the reflective electrode and again A second polarizing beam splitter that passes through the second liquid crystal region, enters the light that has passed through the second liquid crystal region and exits from the reflective liquid crystal phase modulation unit, and transmits or reflects the incident light to exit.
Provided between the reflective liquid crystal phase modulator and the first polarization beam splitter, and between the reflective liquid crystal phase modulator and the second polarization beam splitter, and the first polarization beam splitter or the second polarization beam. A quarter-wave plate that transmits light traveling back and forth between the beam splitter and the reflective liquid crystal phase modulator, and changes the polarization direction of the light;
By supplying a voltage between the reflective electrode and the transparent electrode, it has a voltage supply unit for applying a predetermined voltage to the liquid crystal,
The light emitted from the first polarizing beam splitter is incident on the second polarizing beam splitter;
Between the light in the first polarization direction incident on the first liquid crystal region and the light in the first polarization direction emitted from the second liquid crystal region, the voltage supply unit according to a voltage applied to the liquid crystal. a reflective liquid crystal phase modulation device phase difference, characterized in Rukoto occur. 2. The reflective liquid crystal phase modulation device according to claim 1, further comprising a reflecting mirror that reflects light emitted from the first polarizing beam splitter and emits the light to the second polarizing beam splitter. 3. The reflection type liquid crystal phase modulation device according to claim 1, wherein the reflection type liquid crystal phase modulation device has the same polarization direction of incident light and emission light. A plurality of the reflection type liquid crystal phase modulation devices according to claim 1, wherein the plurality of reflection type liquid crystal phase modulation devices are formed on a common semiconductor substrate, and the plurality of reflection type liquid crystal phase modulation devices are provided. The light emitted from the second polarization beam splitter of any one of the reflection type liquid crystal phase modulation devices is the first polarization of any one of the plurality of reflection type liquid crystal phase modulation devices . A reflection-type liquid crystal phase modulation system provided as light incident on a beam splitter .

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