JP2003035630A - Optical element, and evaluating apparatus, evaluating method and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element-evaluating apparatus and the like which can evaluate not only a reflection spectrum of optical elements, but wavelength dispersion characteristics of the elements. SOLUTION: A continuum outputted from a first light source 11 is inputted through a selector switch 13 and an optical isolator 14 to a first end 21 of a photocoupler 20. The light is branched to two at the photocoupler 20 and outputted from a second end 22 and a third end 23 respectively. The continuum outputted from the second end 22 is partly reflected by a diffraction light element 2 of an optical waveguide type, and the reflected continuum is inputted to the second end 22 and outputted from a fourth end 24. The continuum outputted from the third end 23 is reflected by a total reflection end 31 through a selector switch 33 and a lens 32, inputted to the third end 23 through the lens 32 and the selector switch 33, and outputted from the fourth end 24. The continuum outputted from the fourth end 24 is inputted to a first detector 41 through a selector switch 43, and its power is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for evaluating characteristics of an optical element, and a method for manufacturing an optical element.

[0002]

2. Description of the Related Art Various optical elements are used in optical communication systems and the like, and among them, an optical waveguide type diffraction grating element is an example of an optical element in which the wavelength dependence of characteristics is important. An optical waveguide type diffraction grating element is one in which a refractive index modulation is formed along the longitudinal direction of an optical waveguide (for example, an optical fiber) to form a diffraction grating, and a specific wavelength of light propagating in the optical waveguide is formed. Can be used as an optical filter because it can selectively reflect the light of (1) by the diffraction grating and transmit the light of other wavelengths.

Such an optical waveguide type diffraction grating element is manufactured as follows. That is, a phase grating mask is arranged on the side of the optical waveguide, and the optical waveguide is irradiated with refractive index change inducing light (light having a wavelength that induces a change in the refractive index of the optical waveguide) through the phase grating mask. Along with this irradiation, the + 1st-order diffracted light and the -1st-order diffracted light are generated due to the diffraction effect of the phase grating mask, and these interfere with each other to generate an interference fringe. Then, the refractive index of the optical waveguide changes in accordance with the power distribution of the refractive index change inducing light in the interference fringes, whereby a diffraction grating is formed. In addition, the spectrum of the light reflected by the diffraction grating being formed (or the light transmitted through the diffraction grating) is monitored by making the light incident on the optical waveguide and propagated, and the reflection spectrum (or transmission spectrum) is desired. At that point, the irradiation of the refractive index change inducing light is terminated.

[0004]

By the way, in the optical waveguide type diffraction grating element, it is preferable that the absolute value of chromatic dispersion is suppressed to a small value. However, although the above method can evaluate the reflection spectrum (or the transmission spectrum) of the optical waveguide type diffraction grating element, it cannot evaluate the chromatic dispersion, and therefore the wavelength dispersion suppressing optical waveguide type diffraction grating element cannot be evaluated. It cannot be applied to evaluation and manufacturing of lattice elements.
Generally, the above method cannot be applied to the evaluation / manufacturing of an optical element in which not only the reflection spectrum (or transmission spectrum) but also the wavelength dispersion characteristic is important.

The present invention has been made to solve the above problems, and an optical element evaluation apparatus and method capable of evaluating not only the reflection spectrum of an optical element but also wavelength dispersion characteristics, and the use thereof. Another object of the present invention is to provide a method for manufacturing an optical element.

[0006]

An optical element evaluation apparatus according to the present invention is an apparatus for evaluating the characteristics of an optical element,
(1) A light source section that outputs continuous light having a continuous spectrum in the reflection band of the optical element, and (2) a first end, a second end, a third end, and a fourth end, the first end being the light source section. Connected to the
The second end is connected to the optical element, the light input to the first end is branched and output to the second end and the third end, the light input to the second end is output to the fourth end, and the third end The optical system that outputs the light input to the 4th end to (4) the light output from the 3rd end of the optical system is input, and the light is switched to either the total reflection end or the non-reflection end. It is possible, the total reflection end is movable along the light incident direction, and when switched to the total reflection end, the light output from the third end is reflected by the total reflection end and reflected by the total reflection end. A reflector for inputting light to the third end,
(4) A first detector that detects the power of the light output from the fourth end of the optical system, and (5) a second detector that detects the spectrum of the light output from the fourth end of the optical system, It is characterized by including.

An optical element evaluation method according to the present invention is a method for evaluating the characteristics of an optical element, which comprises (1) first end, second
An end, a third end, and a fourth end, the light input to the first end is branched and output to the second end and the third end, and the light input to the second end is output to the fourth end, An optical system that outputs the light input to the third end to the fourth end is used. (2) The light source unit is connected to the first end of the optical system, and continuous light having a continuous spectrum in the reflection band of the optical element is used as the light source unit. (3) Connect the optical element to the second end of the optical system, reflect the light output from the second end by the optical element, and input the reflected light to the second end. (4) The third end of the optical system is the total reflection end, and the light output from the third end is reflected by the total reflection end at each position of the total reflection end along the light incident direction. The reflected light is input to the third end, and the power of the light output from the fourth end at this time is detected. (5) The third end of the optical system is set as the non-reflection end. And detecting the spectrum of al the light output.

According to the optical element evaluation apparatus or method of the present invention, light having a continuous spectrum in the reflection band of the optical element which is the object of evaluation is output from the light source section and input to the first end of the optical system. , Is branched in this optical system, and is output from each of the second end and the third end of the optical system. The light output from the second end of the optical system is reflected by the optical element, and the reflected light is input to the second end of the optical system and output from the fourth end. When the third end of the optical system is the total reflection end, the light output from the third end of the optical system is reflected by the total reflection end, and the reflected light is
The light enters the third end of the optical system and is output from the fourth end together with the light reflected by the optical element. Then, by detecting the power of the light output from the fourth end of the optical system at each position of the total reflection end, the wavelength dispersion characteristic of the optical element is evaluated. On the other hand, when the third end of the optical system is the non-reflection end, the light output from the third end of the optical system is not reflected. Then, only the light reflected by the optical element is output from the fourth end of the optical system, and the reflection spectrum of the optical element is evaluated by detecting the spectrum of the light.

In the optical element evaluation apparatus according to the present invention, it is preferable that the light source section selects and outputs either the continuous light or the pulsed light. Further, in the optical element evaluation method according to the present invention, the pulsed light is input from the light source unit to the first end of the optical system, the third end of the optical system is set as the non-reflection end, and at this time, output from the fourth end. It is preferable to detect the time change of the power of light. In this case, the pulsed light output from the light source unit is input to the first end of the optical system, branched in this optical system, and output from each of the second end and the third end of the optical system. . The light output from the second end of the optical system is reflected by the optical element, and the reflected light is input to the second end of the optical system and output from the fourth end. On the other hand, the third end of the optical system is a non-reflective end, and the light output from the third end of the optical system is not reflected. Therefore, only the light reflected by the optical element is output from the fourth end of the optical system, and the time change of the power of the light is detected, so that the wavelength dispersion characteristic of the optical element is evaluated.

In the optical element evaluation apparatus according to the present invention, it is preferable that the light source section repeatedly outputs the pulsed light. Further, in the optical element evaluation method according to the present invention, it is preferable that the pulsed light is repeatedly output from the light source unit. In this case, since the pulsed light is repeatedly output from the light source unit, the light output from the fourth end of the optical system is
The reflected light from the optical element is superimposed on each pulsed light output from the light source unit. Therefore, by detecting the time change of the power of the light output from the fourth end of the optical system, the degree of temporal separation of the reflected light from the optical element with respect to each pulsed light output from the light source unit can be determined. Then, the wavelength dispersion characteristics of the optical element are evaluated.

An optical element manufacturing method according to the present invention is characterized by manufacturing an optical element while evaluating the characteristics of the optical element by using the above-described optical element evaluation apparatus or optical element evaluation method according to the present invention. An optical element according to the present invention is characterized by being manufactured by the above-described optical element manufacturing method according to the present invention. In this optical element manufacturing method, both the reflection spectrum and the wavelength dispersion characteristic of the optical element are evaluated in the process of manufacturing the optical element. Then, when the reflection spectrum and the wavelength dispersion characteristic are respectively desired, the manufacturing of the optical element is completed. In this way, the desired optical element can be manufactured with high yield in terms of both the reflection spectrum and the wavelength dispersion characteristic.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a block diagram of an optical element evaluation apparatus 1 according to this embodiment. In the optical element evaluation apparatus 1 shown in this figure, when the optical waveguide type diffraction grating element 2 is manufactured using the phase grating mask 3, the optical waveguide type diffraction grating element 2 is manufactured.
To evaluate the characteristics of. This optical element evaluation apparatus 1
Is a light source unit 10, an optical coupler 20, a reflection unit 30, a detection unit 4
0 and a control unit 50, and these are optically connected by an optical fiber.

The light source unit 10 includes a first light source 11 and a second light source 1.
2, a changeover switch 13 and an optical isolator 14. The first light source 11 outputs continuous light having a continuous spectrum in the reflection band (wavelength range from the maximum reflectance to 3 dB down) of the optical waveguide type diffraction grating element 2 which is the object of evaluation, and its continuous side. The light is low coherent. As the first light source 11, for example, SLD (Super Lu
minescent diode) light source is preferably used. The second light source 12 outputs pulsed light having a wavelength within the reflection band of the optical waveguide type diffraction grating element 2. For example, a semiconductor laser light source is used as the second light source 12. Changeover switch 1
3 inputs the light output from each of the first light source 11 and the second light source 12, selects any one of these lights, and outputs it to the optical isolator 14. The optical isolator 14 passes the light reaching from the changeover switch 13 toward the optical coupler 20, but does not pass the light in the opposite direction.

The optical coupler 20 is, for example, an optical fiber coupler and has a first end 21, a second end 22, a third end 23 and a fourth end 24. The first end 21 is connected to the light source unit 10, the second end 22 is connected to the optical waveguide type diffraction grating element 2, the third end 23 is connected to the reflection unit 30, and the fourth end 24 is connected to the detection unit 40. Has been done. The optical coupler 20 splits the light input to the first end 21 into two, outputs the split light to the second end 22 and the third end 23, and outputs the light input to the second end 22 to the fourth end 2.
4 and outputs the light input to the third end 23 to the fourth end 24.

The reflector 30 includes a total reflection end 31 and a lens 32.
And a changeover switch 33. Changeover switch 3
3 receives the light reaching from the third end 23 of the optical coupler 20 and outputs the light to either the lens 32 or the non-reflection end 34. Further, this changeover switch 33 is used for the optical coupler 2
When the light reaching from the third end 23 of 0 is output to the lens 32, the light reaching from the lens 32 is output to the third end 23 of the optical coupler 20. The lens 32 is a changeover switch 3
The light input from 3 is converted into parallel light, and the parallel light is output to the total reflection end 31. The total reflection end 31 vertically enters the parallel light that has arrived from the lens 32 and reflects the parallel light in the lens 32.
To reflect. The total reflection end 31 is movable along the light incident direction, and moves due to the action of the piezo element, for example. The non-reflective end 34 is an open end, or the tip thereof is immersed in matching oil, and the changeover switch 3
Do not reflect the light that reaches from 3.

The detector 40 has a first detector 41, a second detector 42 and a changeover switch 43. The changeover switch 43 inputs the light reaching from the fourth end 24 of the optical coupler 20 and outputs the light to the first detector 41 and the second detector 4
Output to either of the two. The first detector 41 detects the power of light that has reached from the changeover switch 43,
For example, a photodiode is preferably used. The second detector 42 detects the spectrum of the light reaching from the changeover switch 43, and for example, a spectrum analyzer is preferably used.

The control unit 50 controls the overall operation of the optical element evaluation apparatus 1. In particular, the control unit 50 controls the switching operation of each of the changeover switch 13, the changeover switch 33, and the changeover switch 43, controls the timing at which each of the first light source 11 and the second light source 12 outputs light, and controls the first detector. 41 and the 2nd detector 42 control the timing which detects light, respectively, and also control the position of the total reflection end 31.

The optical waveguide type diffraction grating element 2 connected to the second end 22 of the optical coupler 20 has a diffraction grating formed by refractive index modulation in the optical waveguide region of the optical waveguide (for example, an optical fiber). is there. This optical waveguide is based on silica glass and has a core region doped with GeO ₂ and a cladding region surrounding the core region. A phase grating mask 3 is arranged on the side of the optical waveguide, and refractive index change inducing light (light having a wavelength that induces a change in the refractive index of the optical waveguide, for example, KrF excimer laser) The laser beam having a wavelength of 248 nm output from the light source is emitted. Along with this irradiation, the + 1st-order diffracted light and the -1st-order diffracted light are generated due to the diffraction action of the phase grating mask 3, and these interfere with each other to generate an interference fringe. Then, the refractive index of the optical waveguide changes according to the power distribution of the refractive index change inducing light in the interference fringes, whereby a diffraction grating is formed, and the optical waveguide type diffractive photon element 2 is manufactured.

Next, the operation of the optical element evaluation apparatus 1 according to this embodiment will be described, and the optical element evaluation method and optical element manufacturing method according to this embodiment will also be described. The optical element evaluation described below is performed when manufacturing the optical element. Optical element evaluation device 1
Operates under the control of the controller 50 and has the following three operation modes.

In the first operation mode, the continuous light output from the first light source 11 is switched by the changeover switch 13 to the optical coupler 2.
The light output from the third end 23 of the optical coupler 20 is input to the first end 21 of 0 and is output from the third end 23 of the optical coupler 20.
The light reflected by 1 and output from the fourth end 24 of the optical coupler 20 is input to the first detector 41 by the changeover switch 43.

In this first operation mode, the continuous light output from the first light source 11 enters the first end 21 of the optical coupler 20 via the changeover switch 13 and the optical isolator 14 and is branched into two in the optical coupler 20. Optical coupler 20
Is output from each of the second end 22 and the third end 23 of the. A part of the continuous light output from the second end 22 of the optical coupler 20 is reflected by the optical waveguide type diffractive optical element 2, and the reflected continuous light is input to the second end 22 of the optical coupler 20. It is output from the fourth end 24. On the other hand, the optical coupler 20
The continuous light output from the third end 23 of the
3 and the lens 32, and is reflected by the total reflection end 31, and the reflected continuous light is input to the third end 23 of the optical coupler 20 via the lens 32 and the changeover switch 33.
It is output from the fourth end 24. Then, the continuous light output from the fourth end 24 of the optical coupler 20 is input to the first detector 41 via the changeover switch 43, and its power is detected.

That is, in this first operation mode, the light output from the light source section 10 is the optical waveguide type diffraction grating element 2.
The continuous light has a continuous spectrum in the reflection band of. The light reaching the first detector 41 is continuous light reflected by the optical waveguide type diffraction grating element 2 and total reflection end 3
The continuous light reflected by 1. Then, by detecting the power of the light reaching the first detector 41, the wavelength dispersion characteristic of the optical waveguide type diffraction grating element 2 is evaluated.
The principle of this evaluation will be described later.

In the second operation mode, the changeover switch 13 causes the continuous light output from the first light source 11 to output the continuous light.
The light output from the third end 23 of the optical coupler 20 is input to the first end 21 of the optical coupler 20 by the changeover switch 33.
4 is output to the optical coupler 20 by the changeover switch 43.
The light output from the fourth end 24 of the input light enters the second detector 42.

In this second operation mode, the continuous light output from the first light source 11 enters the first end 21 of the optical coupler 20 via the changeover switch 13 and the optical isolator 14, and is branched into two in the optical coupler 20. Optical coupler 20
Is output from each of the second end 22 and the third end 23 of the. A part of the continuous light output from the second end 22 of the optical coupler 20 is reflected by the optical waveguide type diffractive optical element 2, and the reflected continuous light is input to the second end 22 of the optical coupler 20. It is output from the fourth end 24. On the other hand, the optical coupler 20
The continuous light output from the third end 23 of the
It reaches the non-reflective end 34 via 3 and is not reflected. Then, the continuous light output from the fourth end 24 of the optical coupler 20 is input to the second detector 42 via the changeover switch 43, and the spectrum thereof is detected.

That is, in this second operation mode, the light output from the light source unit 10 is the optical waveguide type diffraction grating element 2.
The continuous light has a continuous spectrum in the reflection band of. The light reaching the second detector 42 is continuous light reflected by the optical waveguide type diffraction grating element 2. Therefore,
By detecting the spectrum of the light that reaches the second detector 42, the reflection spectrum of the optical waveguide type diffraction grating element 2 is evaluated.

In the third operation mode, the changeover switch 13 inputs the pulsed light output from the second light source 12 to the first end 21 of the optical coupler 20, and the changeover switch 33 changes the pulsed light.
The light output from the third end 23 of the optical coupler 20 is output to the non-reflection end 34, and the changeover switch 43 causes the optical coupler 2
The light output from the fourth end 24 of 0 enters the first detector 41.

In the third operation mode, the pulsed light output from the second light source 12 enters the first end 21 of the optical coupler 20 via the changeover switch 13 and the optical isolator 14, and is branched into two in the optical coupler 20. Optical coupler 20
Is output from each of the second end 22 and the third end 23 of the. A part of the pulsed light output from the second end 22 of the optical coupler 20 is reflected by the optical waveguide type diffractive optical element 2, and the reflected pulsed light is input to the second end 22 of the optical coupler 20, It is output from the fourth end 24. On the other hand, optical coupler 2
The pulsed light output from the third end 23 of 0 reaches the non-reflection end 34 through the changeover switch 33 and is not reflected. Then, the pulsed light output from the fourth end 24 of the optical coupler 20 passes through the changeover switch 43 and the first detector 41.
, And the time change of the power is detected.

That is, in the third operation mode, the light output from the light source unit 10 is the optical waveguide type diffraction grating element 2
The pulsed light has a wavelength within the reflection band of. First detector 41
The light arriving at is the pulse response light reflected by the optical waveguide type diffraction grating element 2. Therefore, the first detector 4
The chromatic dispersion characteristic of the optical waveguide type diffraction grating element 2 is evaluated by detecting the change over time in the power of the light reaching 1.

Alternatively, in the third operation mode, it is also preferable that the pulsed light is repeatedly output from the second light source 12 at regular time intervals. In this case, the light that reaches the first detector 41 is a superposition of the reflected light from the optical waveguide type diffraction grating element 2 with respect to each pulsed light output from the second light source 12. Therefore, based on the detection result by the first detector 41, the degree of temporal separation of the reflected light from the optical waveguide type diffraction grating element 2 for each pulsed light output from the second light source 12 is obtained, The wavelength dispersion characteristic of the optical waveguide type diffraction grating element 2 is evaluated.

Next, the principle of chromatic dispersion characteristic evaluation in the first operation mode will be described. The electric field E (t) of continuous light output from the first light source 11 is

[Equation 1] It is expressed by Where ω is the frequency of light and S
(ω) is the power spectral density, and φ (ω) is the frequency-dependent phase.

Assuming that the phase φ (ω) has no correlation between frequencies ω and ω ′ different from each other,

[Equation 2] The following relational expression holds. Here, the square brackets on the left side represent the time average, and δ on the right side represents the Dirac delta function.

The electric field E ₁ (t) of the continuous light reflected by the total reflection edge 31 and reaching the first detector 41 is

[Equation 3] It is expressed by Here, it is assumed that the reflectance at the total reflection end 31 is constant regardless of the frequency ω of light. t
₁ indicates that the continuous light output from the first light source 11 is the total reflection end 3
It is the time until it reaches the first detector 41 after being reflected by 1.

On the other hand, the reflection characteristic of the optical waveguide type diffraction grating element 2 is represented by the reflectance r (ω) depending on the frequency ω of light and the delay time t ₂ . This delay time t ₂ is equal to the first light source 1
This corresponds to the time required for the light having the frequency ω output from 1 to reach the first detector 41 after being reflected at a predetermined position (reflectance r (ω)) on the optical waveguide type diffraction grating element 2. The electric field E ₂ (t) of continuous light that reaches the first detector 41 after being reflected by the optical waveguide type diffraction grating element 2 is

[Equation 4] It is expressed by

The electric field of light reaching the first detector 41 is composed of an electric field E ₁ (t) represented by the above equation (3) and an electric field E ₂ (t) represented by the above equation (4). It is a sum. Therefore, the power P (τ) of the light detected by the first detector 41 is

[Equation 5] It is expressed by τ is the difference between time t ₁ and time t _2, and depends on the position of the total reflection end 31. On the right side of this equation, E ₁ (t) ^* E ₁ (t) and E ₂ (t) ^* E ₂ (t) are terms that do not depend on the time difference τ, and are constant offset values. Yes, and ignore it from here on.

In this equation (5), the term that does not depend on the time difference τ is omitted, and only the term that depends on the time difference τ is left. Further, considering the above equation (2),

[Equation 6] It is expressed by Here, Re represents the real part. The current value I (τ) output from the first detector 41 (eg, photodiode) is

[Equation 7] It is expressed by As can be seen from the equation (7), the current value I (τ) output from the first detector 41 is the product S (ω) · r.
It is proportional to the intensity of the Fourier transform of (ω). Therefore, the wavelength difference characteristic of the optical waveguide type diffraction grating element 2 can be evaluated by changing the time difference τ by moving the total reflection end 31 and obtaining the time difference τ dependency of the current value I (τ). .
An example thereof is shown in FIGS. 2 and 3.

FIG. 2 shows the first detector 4 when the refractive index modulation amplitude distribution of the optical waveguide type diffraction grating element 2 is a Gaussian distribution.
It is a figure which shows the power of the light detected by 1. Figure 3
FIG. 4 is a diagram showing the power of light detected by the first detector 41 when the refractive index modulation amplitude distribution of the optical waveguide type diffraction grating element 2 has a phase inversion part. Each figure (a) shows the refractive index modulation amplitude distribution of the optical waveguide type diffraction grating element 2. In each drawing (b), the position of the total reflection end 31 (corresponding to the time difference τ) is normalized by the refractive index modulation formation region length and is shown on the horizontal axis,
The current value I (τ) output from the first detector 41 (that is, the power of the light detected by the first detector 41) is shown on the vertical axis.

As shown in FIGS. 2B and 3B, in both cases, as the total reflection end 31 moves away from the lens 32 (that is, the time difference τ increases),
The power of the light detected by the first detector 41 repeatedly increases and decreases. With respect to the position of the total reflection end 31, the first detector 41
The power of the light detected by has many peaks. Each of these peaks represents the case where the number of times of reflection of light in the optical waveguide type diffraction grating element 2 is 1, 3, 5, ... In addition, the fact that a large number of peaks occur in this way means that the expression (6) above is a complex function and the sign may be inverted, and the expression (7) above takes the absolute value of this expression (6). It can be explained from the fact that it is one.

The following can be said by comparing the envelopes connecting the respective peak points in FIG. 2 (b) and FIG. 3 (b). That is, in FIG. 2B, the power of the light detected by the first detector 41 becomes maximum at the first first peak, and gradually decreases at each subsequent peak, but the degree of decrease is gradual. Is. On the other hand, in FIG. 3B, the power of the light detected by the first detector 41 gradually increases from the first peak to the sixth peak, and then the sixth power.
It becomes the maximum at the peak and decreases sharply after the sixth peak. Thus, compared to FIG. 2B, FIG.
Then, the power of the light detected by the first detector 41 rapidly decreases after reaching the maximum value, which means that the absolute value of the chromatic dispersion is small. Actually, the optical waveguide type diffraction grating element 2 has a case where the refractive index modulation amplitude distribution has a phase inversion part, as compared with the case where the refractive index modulation amplitude distribution is a Gaussian distribution (FIG. 2A) (FIG. 3A). ), The absolute value of chromatic dispersion is suppressed to a small value.

In the present embodiment, the optical waveguide type diffraction grating element 2 is manufactured by irradiating the optical waveguide with the refractive index change inducing light through the phase grating mask 3, and at the time of manufacturing the optical waveguide type diffraction grating element 2. The optical element evaluation apparatus 1 or the optical element evaluation method is used to evaluate both the reflection spectrum and the wavelength dispersion characteristic of the optical waveguide type diffraction grating element 2. Then, when the reflection spectrum and the wavelength dispersion characteristic are respectively desired, the irradiation of the refractive index change inducing light is ended, and the manufacture of the optical waveguide type diffraction grating element 2 is ended. Therefore, according to the present embodiment, the optical waveguide type diffraction grating element 2 which is desired with respect to both the reflection spectrum and the wavelength dispersion characteristic can be manufactured with high yield.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above embodiment, the object to be evaluated by the optical element evaluation apparatus 1 is
Although it is the optical waveguide type diffraction grating element 2, other optical elements may be used. A half mirror may be used instead of the optical coupler 20.

[0042]

As described in detail above, according to the optical element evaluation apparatus or method of the present invention, light having a continuous spectrum in the reflection band of the optical element which is the object of evaluation is output from the light source section. Is input to the first end of the optical system, branched in this optical system, and output from each of the second end and the third end of the optical system. The light output from the second end of the optical system is reflected by the optical element, and the reflected light is input to the second end of the optical system and output from the fourth end. When the third end of the optical system is the total reflection end, the light output from the third end of the optical system is reflected by the total reflection end, and the reflected light is reflected by the third end of the optical system. It is input and output from the fourth end together with the light reflected by the optical element. Then, by detecting the power of the light output from the fourth end of the optical system at each position of the total reflection end, the wavelength dispersion characteristic of the optical element is evaluated. On the other hand, when the third end of the optical system is the non-reflection end,
The light output from the third end of the optical system is not reflected. Then, only the light reflected by the optical element is output from the fourth end of the optical system, and the reflection spectrum of the optical element is evaluated by detecting the spectrum of the light.

As described above, according to the optical element evaluation apparatus or method of the present invention, both the wavelength dispersion characteristic and the reflection spectrum of the optical element are evaluated. Further, in the optical element manufacturing method according to the present invention, in the process of manufacturing the optical element, both the reflection spectrum and the wavelength dispersion characteristic of the optical element are evaluated, and the reflection spectrum and the wavelength dispersion characteristic are respectively desired. At this point, manufacturing of the optical element is completed. In this way, the desired optical element can be manufactured with high yield in terms of both the reflection spectrum and the wavelength dispersion characteristic.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical element evaluation apparatus 1 according to the present embodiment.

FIG. 2 is a diagram showing the power of light detected by a first detector 41 when the refractive index modulation amplitude distribution of the optical waveguide type diffraction grating element 2 is a Gaussian distribution.

FIG. 3 is a diagram showing the power of light detected by a first detector 41 when the refractive index modulation amplitude distribution of the optical waveguide type diffraction grating element 2 has a phase inversion part.

[Explanation of symbols]

1 ... Optical element evaluation device, 2 ... Optical waveguide type diffraction grating element,
3 ... Phase grating mask, 10 ... Light source part, 11 ... First light source,
12 ... 2nd light source, 13 ... Changeover switch, 14 ... Optical isolator, 20 ... Optical coupler, 21 ... 1st end, 22 ... 2nd
Edge, 23 ... Third edge, 24 ... Fourth edge, 30 ... Reflecting portion, 31
… Total reflection edge, 32… Lens, 33… Changeover switch, 34
... non-reflective end, 40 ... detector, 41 ... first detector, 42 ...
2nd detector, 43 ... Changeover switch, 50 ... Control part.

Claims (8)

[Claims] 1. A device for evaluating characteristics of an optical element, comprising: a light source section that outputs continuous light having a continuous spectrum in a reflection band of the optical element; a first end, a second end, a third end, and a first end. Having four ends, the first
The end is connected to the light source unit, the second end is connected to the optical element, the light input to the first end is branched and output to the second end and the third end, and the second end An optical system that outputs the light input to the fourth end and outputs the light input to the third end to the fourth end, and the light output from the third end of the optical system is input, The light can be switched to either a total reflection end or a non-reflection end, the total reflection end is movable along the light incident direction, and when the total reflection end is switched, The light output from the third end is reflected by the total reflection end and the reflected light is input to the third end; and the power of the light output from the fourth end of the optical system. A first detector for detecting, and a second detector for detecting a spectrum of light output from the fourth end of the optical system. Optical element evaluation apparatus comprising: the output device, the. 2. The light source unit selects and outputs one of the continuous light and the pulsed light.
The optical element evaluation device described. 3. The optical element evaluation apparatus according to claim 2, wherein the light source section repeatedly outputs the pulsed light. 4. A method for evaluating characteristics of an optical element, comprising: a first end, a second end, a third end and a fourth end,
The light input to the end is branched and output to the second end and the third end, the light input to the second end is output to the fourth end, and the light input to the third end is output to the first end. An optical system that outputs to four ends is used, a light source unit is connected to the first end of the optical system, and continuous light having a continuous spectrum in the reflection band of the optical element is input from the light source unit to the first end. The optical element is connected to the second end of the optical system, the light output from the second end is reflected by the optical element, and the reflected light is input to the second end, The third end of the system is a total reflection end, and the light output from the third end is reflected by the total reflection end at each position of the total reflection end along the light incident direction, and the reflected light To the third end, and at this time, the power of the light output from the fourth end is Out, the third end of the optical system is no reflection end, and detect the spectrum of the light output from the fourth end in this case, the optical element evaluation method characterized by. 5. The pulsed light is input from the light source unit to the first end of the optical system, and the third end of the optical system is a non-reflection end, and the light output from the fourth end at this time. 5. The optical element evaluation method according to claim 4, wherein the change in the power with time is detected. 6. The optical element evaluation method according to claim 5, wherein the pulsed light is repeatedly output from the light source unit. 7. An optical element manufacturing method, characterized in that the optical element is manufactured while the characteristics of the optical element are evaluated by using the optical element evaluation apparatus according to claim 1 or the optical element evaluation method according to claim 4. Method. 8. An optical element manufactured by the optical element manufacturing method according to claim 7.