JP2000075165A - Virtually imaged phased array having lens disposed in order to obtain broad beam width - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the simultaneous sepn. of plural carriers from wavelength divided multiples light with simple constitution by using an apparatus which has first to third lenses and an angle dispersion device and receives input light of respective wavelengths within a continuous range of wavelengths. SOLUTION: The first lens 200 collimates input light when viewed laterally. The lens does not possess the effect of a lens when viewed from front. The second lens 202 receives the input light from the first lens 200 and condenses the input light when viewed laterally. The lens does not possess the effect of a lens when viewed from front. The third lens 204 receives the input light from the second lens 202 and collimates the input light when viewed from front. The lens does not possess the effect of a lens when viewed laterally. The light from the third lens is received in a virtually imaged phased array(VIPA) 76. This VIPA 76 forms the output light which is spatially discriminatable from the output light formed with respect to the input light having any other wavelengths within the continuous range of the wavelengths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a virtual imaged phased array (VIPA).
Magnetized phased array, that is, wavelength division multiplexing that receives wavelength division multiplexed light composed of multiple carriers, and that separates the wavelength division multiplexed light into a plurality of spatially distinguishable luminous fluxes corresponding to a plurality of carriers, respectively. About the vessel.

[0002]

2. Description of the Related Art Wavelength division multiplexing is used in fiber optic communications to transmit high speed, relatively large amounts of data. More specifically, a plurality of carriers, each of which is modulated with information, are multiplexed into wavelength multiplexed light. The wavelength division multiplexed light is then transmitted to the receiver via one optical fiber.
The receiver demultiplexes the wavelength division multiplexed light into each carrier and detects each carrier. As described above, the communication system can transmit a relatively large amount of data using the optical fiber.

[0003] Therefore, the ability of a receiver to accurately demultiplex wavelength division multiplexed light greatly affects the performance of a communication system.
For example, even if many carriers are multiplexed into wavelength division multiplexed light, such wavelength division multiplexed light is
If the receiver cannot accurately demultiplex the WDM light, it should not be transmitted. Therefore, it is desired that the receiver has a high-precision wavelength demultiplexer.

FIG. 1 is a diagram showing a conventional filter using a multilayer interference film for use as a wavelength demultiplexer. According to FIG. 1, the multilayer interference film 20 includes a transparent substrate 22
Formed on top. Light 24, which must be a collimated light, impinges on film 20, and is then repeatedly reflected within film 20. Depending on the optical conditions determined by the characteristics of the film 20, the light 2 having the wavelength λ2
Only 6 can be transmitted. The light 28 includes all light that does not meet the optical conditions, but does not pass through the film 20 and is reflected. Therefore, the filter shown in FIG. 1 is useful for demultiplexing a wavelength division multiplexed light including only two carriers of different wavelengths λ1 and λ2. However, such a filter, itself,
Wavelength division multiplexed light having more carriers cannot be split.

FIG. 2 is a diagram showing a conventional Fabry-Perot interferometer used as a wavelength demultiplexer. According to FIG. 2, the high-reflectivity reflective films 30 and 32 are parallel to each other.
The light 34, which must be a parallel light, impinges on the reflective film 30 and is reflected between the reflective films 30 and 32 many times. The light 36 having the wavelength λ2 that satisfies the transmission condition determined by the characteristics of the Fabry-Perot interferometer passes through the reflection film 32. Light 38 of wavelength λ1 that does not satisfy the transmission condition is
Is reflected. In this way, light having two different wavelengths can be split into two different lights, each corresponding to two different wavelengths. Thus, like the filter shown in FIG. 1, a conventional Fabry-Perot interferometer is useful for demultiplexing a wavelength division multiplexed light including only two carriers of different wavelengths λ1 and λ2. However, such Fabry-Perot interferometers cannot split wavelength division multiplexed light having more than two carriers.

FIG. 3 shows a conventional Michelson interferometer used as a wavelength demultiplexer. According to FIG. 3, the parallel light 40 enters the half mirror 42 and is split into a first light 44 and a second light 46 which are perpendicular to each other. The reflection mirror 48 reflects the first light 44, and the reflection mirror 50 reflects the second light 46. The distance between the half mirror 42 and the reflection mirror 48 and the distance between the half mirror 42 and the reflection mirror 50 indicate an optical path difference. The light reflected by the reflection mirror 48 is returned to the half mirror 42, reflected by the reflection mirror 50, and interferes with the light returned to the half mirror 42. As a result, the lights 52 and 54 having the wavelengths λ1 and λ2 are separated from each other. The filter in Figure 1
Like the Fabry-Perot interferometer of FIG. 2, the Michelson interferometer of FIG. 3 is useful for demultiplexing wavelength division multiplexed light containing only two carriers of different wavelengths λ1 and λ2. However, such a Michelson interferometer cannot split a wavelength division multiplexed light having more than two carriers.

It is possible to combine several filters, Fabry-Perot interferometers or Michelson interferometers into a large array so that additional wavelength carriers can be separated from one wavelength division multiplex. However, such arrays are expensive, inefficient, and result in unexpectedly large receivers.

[0008] Diffraction gratings and waveguide array gratings are often used to split wavelength division multiplexed light consisting of two or more different wavelength carriers. FIG. 4 is a diagram illustrating a conventional diffraction grating for demultiplexing wavelength division multiplexed light. FIG.
According to the above, the diffraction grating 56 has an uneven surface 58. The parallel light 60 having a plurality of different wavelength carriers is applied to the uneven surface 5.
8 is incident. Each wavelength carrier is reflected and interferes between reflected light from different steps of the grating. as a result,
Carriers 62, 64 and 66 of different wavelengths are
6 are output at different angles and are separated from each other.

However, the diffraction grating outputs carriers of different wavelengths with a relatively small angle difference. Therefore, the angular dispersion created by the diffraction grating is very small. As a result, it becomes difficult for the receiver to accurately receive various carrier signals demultiplexed by the diffraction grating. This problem is particularly serious in a diffraction grating that splits wavelength division multiplexed light having a large number of carriers having relatively close wavelengths.

[0010] Furthermore, the diffraction grating is affected by the polarization of the incident light. Therefore, the polarization of the incident light can affect the performance of the diffraction grating. In addition, due to the uneven surface of the diffraction grating, a complicated manufacturing process is required to manufacture an accurate diffraction grating.

FIG. 5 is a diagram showing a conventional waveguide array grating for demultiplexing wavelength division multiplexed light. According to FIG. 5, light consisting of a plurality of different wavelength carriers is applied to the input port 6.
The light is received through the optical waveguide 8 and branched into a number of waveguides 70.
A light output port 72 is provided at an end of each waveguide 70 and has an output light 74.
Is generated. The waveguides 70 have different lengths from each other, and thus provide optical paths of different lengths. Thus, the light passing through the waveguide 70 has different path lengths, and thus interferes with each other through the output port 72, forming an output 74 in different directions for different wavelengths.

In a waveguide array grating, the angular dispersion is
By configuring the waveguide appropriately, it can be adjusted to some extent. However, waveguide array gratings are affected by temperature changes and other environmental factors. Therefore, it is difficult to properly adjust the performance due to temperature changes and environmental factors.

Accordingly, an object of the present invention is to provide a simple configuration,
An object of the present invention is to provide a wavelength demultiplexer capable of simultaneously separating a plurality of carriers from wavelength division multiplexed light. It is a further object of the present invention to provide a wavelength demultiplexer that disperses separated carriers with relatively large angular dispersion and is resistant to changes in environmental conditions.

[0014]

The object of the present invention is achieved by providing an apparatus having side and front faces for receiving input light of each wavelength within a continuous range of wavelengths. The equipment is
First, second, and third lenses and an angular dispersion device are provided. The first lens collimates the input light when viewed from the side, and has no effect as a lens when viewed from the front. The second lens receives the input light from the first lens, collects the input light when viewed from the side, and has no lens effect when viewed from the front. The third lens receives input light from the second lens, collimates the input light when viewed from the front, and has no lens effect when viewed from the side. The angular dispersion device has first and second surfaces. The second surface has a reflectance for transmitting a part of the incident light. The angular dispersion device receives input light from the third lens. The first and second surfaces couple the input light to the first
It is arranged to reflect a plurality of times between the first and second surfaces and to transmit a plurality of lights through the second surface. The plurality of transmitted lights interfere with each other to produce output light that is spatially distinguishable from output light generated for input light having any other wavelength within the continuous range of wavelengths.

The object of the present invention is further achieved by providing an apparatus having side and front faces for receiving input light of each wavelength within a continuous range of wavelengths. Where the device is
It includes first and second lenses and an angular dispersion device. The first lens receives input light, acts as a lens when viewed from the side, and has no lens function when viewed from the front. The second lens receives input light from the first lens, acts as a lens when viewed from the front, and has no lens effect when viewed from the side. The angular dispersion device has first and second surfaces. The second surface has a reflectance for transmitting a part of the incident light. The angular dispersion device receives input light from the second lens. The first and second surfaces couple the input light to the first and second surfaces.
Are arranged such that the light is reflected a plurality of times between the surfaces and a plurality of lights are transmitted through the second surface. The plurality of transmitted lights interfere with each other to produce output light that is spatially distinguishable from output light generated for input light having any other wavelength within the continuous range of wavelengths.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiment of the present invention will now be described in detail. These examples are illustrated in the accompanying drawings. Like reference numerals refer to like components throughout.

FIG. 6 illustrates a virtual imaged phased array (VIP) according to one embodiment of the present invention.
FIG. Further, hereinafter, "wavelength demultiplexer",
The terms "virtual imaged phased array" and "VIPA" are used interchangeably to describe various embodiments of the present invention.

In FIG. 6, VIPA 76 is preferably comprised of a thin plate of glass. Input light 77
Is focused on a line 78 by a lens 80, such as a semi-cylindrical lens, and the input light 77 travels into the VIPA 76. Line 78
Is hereinafter referred to as “focal line 78”. The input light 77 is VI
The light propagates radially from a focal line 78 inside the PA 76. VI
Next, the PA 76 outputs the light beam 82 of the collimated light. Here, the output angle of the light flux 82 changes as the wavelength of the input light 77 changes. For example, if the input light 77 has a wavelength λ
In the case of 1, the VIPA 76 has the luminous flux 82a of the wavelength λ1.
Is output in a specific direction. When the input light 77 has the wavelength λ2, the VIPA 76 outputs the light beam 82b having the wavelength λ2 in a different direction. Accordingly, the VIPA 76 generates light fluxes 82a and 82b that are spatially distinguishable from each other. Input light 7
7 includes both wavelengths λ1 and λ2, VI
The PA 76 outputs both the light beams 82a and 82b at the same time.

FIG. 7 illustrates V, according to one embodiment of the present invention.
FIG. 4 is a diagram showing an IPA 76 in detail. According to FIG.
The PA 76 includes, for example, a plate 120 made of glass, and has reflection films 122 and 124 thereon. The reflective film 122 is preferably about 95% or more,
It has a reflectance of less than 100%. Reflective film 124
Preferably has a reflectivity of approximately 100%. The illumination window 126 is formed on the plate 120 and preferably has a reflectance of approximately 0%.

The input light 77 passes through an illumination window,
The light is focused on the focal line 78 by the lens 80,
And 124 are caused by multiple reflections. The focal line 78 preferably corresponds to the plate 120 on which the reflective film 122 is formed.
On the surface. The focal line 78 is essentially a line focused on the reflective film 122 via the irradiation window 126. The width of the focal line 78 can be referred to as the “beam waist” of the input light 77 when collected by the lens 80. Therefore, the embodiment of the present invention shown in FIG. 7 sets the beam waist of the input light 77 to the far surface of the plate 120 (that is, the surface having the reflective film 122 thereon).
Focus on By focusing the beam waist on the far side of the plate 120, this embodiment of the invention provides (i) the area of the input light 77 as it passes through the illumination window 126 (eg, as described in more detail below, FIG.
And (ii) the reflection film 124 when the input light 77 is first reflected by the reflection film 124.
The upper light area (eg, FIG. 1, described in more detail below)
It reduces the likelihood of an overlap with the region "b") shown at 0. It is desirable to reduce such overlap to ensure proper operation of the VIPA.

In FIG. 7, the optical axis 132 of the input light 77
Has a small tilt angle θ ₀ . Assuming that the reflectance of the reflective film 122 is 95%, at the first reflection of the reflective film 122, 5% of the light passes through the reflective film 122 and diffuses after the beam waist, and 95% of the light is reflected on the reflective film 124. Reflected toward. After being first reflected by the reflective film 124, the light again strikes the reflective film 122, but is shifted by an amount of d. Then, 5% of the light passes through the reflective film 122. Similarly, as shown in FIG. 7, light is split into many paths separated by a fixed distance d. The beam shape of each pass is formed such that the light is diffused from the virtual image 134 of the beam waist. The virtual image 134 is
Are arranged at a constant interval 2t along a line perpendicular to.
Here, t is the thickness of the plate 120. Virtual image 134
The positions of the beam waist in are naturally arranged, and it is not necessary to adjust the respective positions. The light diffused from the virtual image 134 interferes with each other, and the collimated light 136 propagates in a direction that changes according to the wavelength of the input light 77.
To form

The interval between the optical paths is d = 2tSin θ ₀ ,
The difference in path length between adjacent beams is 2tCosθ _0. The angular dispersion is proportional to the ratio of these two numbers,
This ratio is cot θ ₀ . As a result, VIPA
Produces a fairly large angular dispersion.

As can be easily understood from FIG.
The term "y imaged phased array"
From the formation of the sequence of FIG. 8 illustrates a line VIA of the VIPA 76 shown in FIG. 6 according to an embodiment of the present invention.
It is a figure showing the section along II-VIII. According to FIG.
Plate 120 has reflective surfaces 122 and 124 thereon. The reflecting surfaces 122 and 124 are parallel to each other and are separated by a thickness t of the plate 120. The reflection surfaces 122 and 124 are typically reflection films formed on the plate 120. As described above, the reflecting surface 124
Has a reflectivity of about 100% except for the irradiation window, and the reflective surface 122 has a reflectivity of about 95% or more. Therefore, the reflective surface 122 has a transmittance of approximately 5% or less, transmits approximately 5% or less of light incident on the reflective surface 122, and reflects 95% or more of the light. You. The reflectance of the reflecting surfaces 122 and 124 is VI
It can be easily changed according to the special application of PA. However, in general, the reflective surface 122 should have a reflectivity of less than 100% to transmit some of the incident light.

The reflecting surface 124 has an illumination window 126 thereon. Illumination window 126 transmits light and preferably has no or very low reflectivity. Irradiation window 1
26 receives the input light 77 and transmits the input light 77 to the reflection surface 12.
The light is received between 2 and 124 and reflected.

FIG. 8 shows a cross section along the line VIII-VIII in FIG. 6, so that the focal line 78 in FIG.
Appears as a "dot". Input light 77 then propagates radially from focal line 78. Further, as shown in FIG. 8, the focal line 78 is disposed on the reflection surface 122. It is not necessary that the focal line 78 be on the reflective surface 122, but moving the position of the focal line 78 will cause a slight change in the characteristics of the VIPA 76.

As shown in FIG. 8, the input light 77
Is incident on the plate 120 via the area A0 of the irradiation window 126. Here, the point P0 indicates a point around the area A0.

The input light 77 is determined by the reflectance of the reflection surface 122.
Is reflected by the reflecting surface 122 and is incident on the area A1 of the reflecting surface 124. Reflective surface 12
4, the input light 77 is reflected from the reflection surface 1.
22, the output light Ou is partially defined by the ray R1.
The light passes through the reflection surface 122 as t1. Thus, FIG.
, The input light 77 causes multiple reflections between the reflection surfaces 122 and 124. Here, the reflection surface 122
Each reflection from also results in a respective output light being transmitted. Therefore, for example, the input light 77
2, A3 and A4, and output light Out2, Ou
Generate t3 and Out4. Point P2 indicates a point around area A2, point P3 indicates a point around area A3, and point P4 indicates a point around area A4. The output light Out2 is defined by the ray R2, and the output light Out2.
3 is defined by ray R3, and output light Out4 is defined by ray R4. FIG. 8 shows output light Out0,
Although only Out1, Out2, Out3, and Out4 are shown, actually, the power of the input light 77 and the reflection surface 12
Due to the reflectivity of 2 and 124, there is more output light. As described in more detail below, the output lights interfere with each other and produce a light beam having a direction that varies according to the wavelength of the input light 77.

FIG. 9 illustrates VI, according to one embodiment of the present invention.
FIG. 3 is a diagram illustrating interference generated by a PA. According to FIG. 9, light traveling from the focal line 78 is reflected by the reflecting surface 124. As described above, the reflection surface 124 is approximately 100%
And thus essentially functions as a mirror. As a result, output light Out1 can reflecting surfaces 122 and 124 is no, so that the output light Out1 was emitted from the focal line I _1, can be optically analyzed. Similarly,
The output lights Out2, Out3, and Out4 are
It can be analyzed optically as emitted from the focal lines I ₂ , I ₃ and I ₄ respectively. Focal lines I ₁ , I
₂ , I ₃ and I ₄ are virtual images of the focal line I ₀ .

Therefore, as shown in FIG. 9, the focal line I ₁ is at a distance 2t from the focal line I ₀ . Here, t is equal to the distance between the reflective surfaces 122 and 124. Similarly, each subsequent focal line is at a distance 2t from the previous focal line. Thus, the focal line I ₂
Is at the focal line I ₁ a distance 2t. Further, each subsequent multiple reflection between the reflective surfaces 122 and 124 produces output light having a lower intensity than the previous output light. Therefore, the output light Out2 has lower intensity than the output light Out1.

As shown in FIG. 9, the output lights from the focal line overlap and interfere with each other. This interference generates a light beam that travels in a specific direction depending on the wavelength of the input light 77. The VIPA according to the above embodiment of the present invention comprises a VIPA
A has the condition of reinforcement, which is a design characteristic of A.
The constructive conditions increase the interference of the output light so that a luminous flux is formed. The condition for constructing VIPA is expressed by the following equation (1).

2t × cos θ = mλ where θ is the propagation direction of the formed light flux measured from a line perpendicular to the surfaces of the reflection surfaces 122 and 124. λ indicates the wavelength of the input light, t indicates the distance between the reflection surfaces 122 and 124, and m indicates an integer.

Therefore, if t is a constant and m is given a specific value, the propagation direction θ of the light beam formed with respect to the input light having the wavelength λ can be determined. More specifically, input light 77 diverges radially from focal line 78 at a particular angle. Thus, input light of the same wavelength travels in many different directions from focal line 78 and is reflected between reflective surfaces 122 and 124. The condition for VIPA reinforcement is that light traveling in a specific direction reinforces through interference of output light to form a light beam having a direction corresponding to the wavelength of input light. Light traveling in a direction different from the specific direction required by the constructive conditions is weakened by the interference of the output light.

FIG. 10 shows V for determining the incident angle or the inclination angle of the input light according to the embodiment of the present invention.
Line VI of the VIPA illustrated in FIG. 6 showing the characteristics of the IPA.
It is a figure showing the section along II-VIII.

Referring to FIG. 10, input light 77 is collected by a cylindrical lens (not shown) and converged on a focal line 78. As shown in FIG. 10, the input light 77 covers an area on the irradiation window 126 having a width equal to “a”. After the input light 77 is reflected once from the reflection surface 122,
The input light 77 is incident on the reflection surface 124 and is reflected by the reflection surface 124.
Covers an area with a width equal to "b" above. Further, FIG.
As shown in FIG.
Travel along the optical axis 132 at an inclination angle θ _{0 with} respect to the perpendicular to

After the tilt angle θ ₀ is first reflected by the reflecting surface 122, the input light 77
Should be set so as not to get out of
In other words, the inclination angle θ ₀ is such that the input light 77
2 and 124, the capture window 126
Should be set so as not to escape from Therefore, in order to prevent the input light 77 from going out of the irradiation window 126, the inclination angle θ ₀ should be set according to the following equation (2).

The term of the optical axis inclination θ ₀ ≧ (a + b) / 4t (a + b) becomes minimum when a = b. This is a situation where the focal line 78 is located on the reflection surface 122.

Accordingly, as shown in FIGS. 6-10, embodiments of the present invention include a VIPA that receives input light having respective wavelengths within a continuous range of wavelengths. VI
The PA causes self-interference by multiple reflection of input light to form output light. The output light is spatially distinguishable from the output light formed for input light of any other wavelength within the continuous range of wavelengths. For example, FIG.
The input light causing multiple reflections between 22 and 124 is illustrated. This multiple reflection is, for each wavelength of the input light 77,
A plurality of output lights Out0, Out1, Out2, Out that interfere with each other so as to generate a spatially distinguishable light flux.
Generate t3 and Out4.

"Self-interference" is a term that refers to interference that occurs between multiple lights or beams from the same light source. Therefore, the output lights Out0, Out1, Out1, and Out4 all come from the same light source (that is, the input light 77) because the output lights Out0, Out1, Out2, Out3, and Out4 all come from the same light source.
The interference of 2, Out3, and Out4 is called self-interference of the input light 77.

According to the above embodiment of the present invention, the input light may be at any wavelength within a continuous range of wavelengths. Therefore, the input light is not limited to a wavelength having a value selected from a range of discrete values.

Further, according to the above embodiment of the present invention, the output light generated for the input light of a specific wavelength within the continuous wavelength range is such that the input light has a different wavelength within the continuous wavelength range. Is spatially distinguishable from the output light generated when Thus, for example, as shown in FIG. 6, the traveling direction of the light beam 82 (ie, the “spatial characteristic”) will be different if the input light 77 is at a different wavelength within a continuous range of wavelengths. Further, for example, referring to FIG. 6, if the input light 77 includes all three wavelengths λ1, λ2, and λ3, the light fluxes 82a, 82b, and 82c are generated simultaneously and travel in different directions.

According to the above embodiment of the present invention, the focal line is described as being on the opposite side of the parallel plate from which input light is input. However, the focal line, for example, in a parallel plate,
It is also possible to be on the surface of the irradiation window or just before the irradiation window.

According to the above embodiment of the present invention, the two reflective films reflect light between them, and the reflectance of one reflective film is approximately 100%. However, a similar effect can be obtained by two reflective films each having a reflectance of less than 100%. For example, both reflective films can have a reflectivity of 95%. In this case, each reflection film transmits light and causes interference. as a result,
A light beam traveling in a direction depending on the wavelength is formed on both sides of the parallel plate on which the reflection film is formed. Thus, the various reflectivities of the various embodiments of the present invention can be easily changed according to the required characteristics of the VIPA.

According to the above embodiment of the present invention, the waveguide device is described as being formed by a parallel plate or by two reflecting surfaces parallel to each other. However, the plates or reflecting surfaces need not necessarily be parallel.

According to the above embodiment of the present invention, VIPA
Uses multiple reflections to maintain a constant phase difference between the interfering lights. As a result, the characteristics of the VIPA are stable, and as a result, changes in optical characteristics due to polarization are reduced. In contrast, the optical properties of conventional diffraction gratings undergo undesirable changes depending on the polarization of the input light.

The above embodiments of the present invention have been described as providing light beams that are "spatially distinguishable" from each other.
“Spatially distinguishable” refers to a light beam that can be distinguished in space. For example, the various luminous fluxes are spatially distinguishable if they are collimated and travel in different directions or are focused at different points. However, the invention is not limited to these detailed examples, and there are other ways to make the light beams spatially distinguishable from one another.

FIG. 11 illustrates an embodiment of the present invention.
FIG. 4 illustrates a VIPA used with a receiver. FIG.
According to 1, the multilayer reflective films 96 and 98 are, for example, 100
It is provided on both sides of a parallel plate 100 made of glass having a thickness t of μm. The parallel plate 100 is 20 to 2000
It is desirable to have a thickness in the range of μm. The reflective films 96 and 98 are preferably multilayer high reflectivity interference films.

The reflectance of the reflection film 98 is approximately 100%, and the reflectance of the reflection film 96 is approximately 95%. However, the reflectance of the reflection film 96 is not limited to 95%,
Different values may be used as long as sufficient light is reflected from the reflective film 96 so that multiple reflections occur between the light and the light. Preferably, the reflectivity of the reflective film 96 is between 80% and 100%.
The range is smaller than a few percent. Further, the reflection film 9
The reflectivity of 8 is not limited to 100%, but needs to be high enough to cause multiple reflections between the reflective films 96 and 98.

The irradiation window 102 receives input light and is arranged on the same surface as the reflection film 96 of the parallel plate 100. The irradiation window 102 is formed by a film having a reflectance of approximately 0% on the surface of the parallel plate 100. As shown in FIG. 11, the boundary between the illumination window 102 and the reflective film 96 is preferably a straight line.

The input light is, for example, an optical fiber (not shown).
And is received by the collimating lens 106. The collimating lens 106 converts the input light into a parallel beam received by the cylindrical lens 108. The cylindrical lens 108 irradiates the parallel beam 104 with the irradiation window 1
The light is condensed on the focal line 110 on the reference numeral 02. The focal line 110 is disposed near and parallel to a straight line boundary between the reflective film 96 and the irradiation window 102. Thus, the input light is input to the parallel plate 100 via the irradiation window 102.

The optical axis of the input light 102 has an inclination angle with respect to the perpendicular of the reflection film 96, and the input light
After entering, it does not escape from the irradiation window 102. Therefore, the tilt angle is set according to the above equation (2).

Once the input light enters the parallel plate 100, the reflective films 96 and 9 (eg, as shown in FIG. 8)
8 causes multiple reflections. Each time input light is incident on reflective film 96, approximately 95% of the light is reflected toward reflective film 98 and approximately 5% of the light is transmitted through reflective film 96 to form output light (eg, Output light Out as shown in FIG.
1). Multiple output light is formed by multiple reflection between the reflection films 96 and 98. The multiple output lights interfere with each other,
A light beam is formed in a propagation direction depending on the wavelength of the input light.

The light beam 112 is collected by a lens 114 that converges the light beam to a convergence point. The convergence point moves along a linear path 116 for different wavelengths of the input light. For example, as the wavelength of the input light increases, the convergence point moves further along the linear path 116. The plurality of receivers 118 are arranged on the linear path 116 to receive the collected light flux 112. Therefore, each receiver 11
Reference numeral 8 is arranged to receive a light beam corresponding to a specific wavelength.

By controlling the distance t between the reflection films or the reflection surfaces of the VIPA, the phase difference of the light reflected between the reflection films or the reflection surfaces can be shifted by a predetermined amount. Resistance can be realized.
Furthermore, the above embodiments of the present invention make only small changes in optical properties that depend on optical polarization.

FIG. 12 is a diagram illustrating a VIPA for use with a receiver, according to another embodiment of the present invention. FIG.
The VIPA described in FIG. 2 is the same as the VIPA described in FIG. 11 except that the reflectances of the reflection films 96 and 98 are exchanged.
Same as A. More specifically, the V shown in FIG.
In IPA, the reflection film 98 has a reflectance of approximately 95%, and the reflection film 96 has a reflectance of approximately 100%. As shown in FIG. 12, the light flux 112 is
Formed by the interference of the output light transmitted therethrough. Therefore, the input light enters from one side of the parallel plate 100, and the light flux 112 is formed on the opposite side of the parallel plate 100. Otherwise, the VIPA described in FIG. 12 is the VIPA described in FIG.
It operates similarly to A.

FIG. 13 illustrates an embodiment of the present invention.
It is a figure which shows a waveguide type VIPA. According to FIG. 13, light 138 is output from an optical fiber (not shown) and
The light is received by a waveguide 140 provided at 42. The waveguide 140 is, for example, lithium niobate. Light 1
38 includes optical signals modulated on a plurality of carriers having different wavelengths.

Light 138 typically has a diffuse width when output from an optical fiber. Therefore, the collimating lens 142 converts the light 138 into parallel light. The parallel light is then collected by a cylindrical lens 144 and converged on a focal line 146. The light then passes through the illumination window 150 from the focal line 146 to the VIP
Emitted into A148.

The VIPA 148 has reflection films 152 and 154 on a parallel plate 156. The reflective film 154 is on one side of the parallel plate 156, and the reflective film 152 and the irradiation window 150 are on the other side of the parallel plate 156. Reflective film 152
Has a reflectance of about 100%, and the reflective film 154 has a reflectance of 10%.
It has a reflectance of less than 0%. The light beam 158 of the light reflected by the parallel plate 156 is output to the opposite side of the parallel plate 156 from the irradiation window 150.

When the input light 138 includes a plurality of wavelengths, a plurality of light beams 158 are formed which travel in different directions depending on the wavelength of the input light 138. The light beam 158 formed by the VIPA 148 is collected by the lens 160 at different points depending on the propagation direction of the light beam 158. Therefore, as shown in FIG.
Light beams 158a, 15 having wavelengths λ1, λ2, and λ3
8b and 158c are formed at different focusing points.

A plurality of light receiving waveguides 162 are provided at the converging point. Each receiving waveguide 162 guides an optical signal and a corresponding carrier having a single wavelength. Thus, a plurality of light beams are received at the same time and transmitted through various channels. Each light receiving waveguide 162 has a corresponding receiver (not shown) provided at a subsequent stage. The receiver is typically a photodiode. Therefore, each light receiving waveguide 16
The light guided by 2 is received and processed by the corresponding receiver.

However, in some VIPA applications,
The beam size in front of the resulting light beam is not large enough for optimal operation, as will be described in detail below.
For example, FIG. 14A is a side view of an apparatus using VIPA, and FIG. 14B is a front view of the apparatus. According to FIGS. 14A and 14B, the input light 104 is
Proceed from input fiber 170 to collimating lens 106. The collimating lens 106 converts the input light 104 into a parallel beam received by the cylindrical lens 108. The cylindrical lens 108 focuses the parallel beam on the VIPA 76 to form a light beam 112.

In the side view of FIG.
a₁And a_TwoOf the beam width of FIG. 14 (B) in the front view.
B_TwoBeam width. FIG.
It is the figure which simplified the side view of (A). Referring to FIG.
Then, the collimating lens 106 and the cylindrical lens 108
Respectively, the focal length f₁And f _Twohave. ideal
Beam size a_TwoIs the thickness of VIPA76 and VIPA7
Determined by parameters such as the angle of incidence of light on
You. As shown in FIG.
Point distance f₁And f_TwoExpand by the ratio of More
Is a_Two/ A₁= F_Two/ F₁ In special applications, a₁, A_TwoAnd input fiber 1
The distance from 70 to VIPA 76 is typically given
Is fixed or fixed. Therefore, the maximum
Focal length f₁Can be easily determined. But beam
Size b_TwoIs the focal length f₁Determined by the maximum allowed
Focal length f₁Is generally a sufficiently large beam size
b_TwoDo not give.

The reason why the large beam size b ₂ is necessary will be described below. FIG. 16 shows the operation of the VIPA 76. FIG. 16 shows the same operation as that shown in FIG. 7, but the first three interfering light beams 1 and 2, respectively.
Beams 2 and 3 are labeled. Each of the interfering lights can have a corresponding beam number. For example, the 100th interference light is beam 100
And so on.

FIGS. 17A, 17B and 17C
FIG. 2 shows front views of the apparatus for beam 1, beam 2 and beam 3, respectively. FIG. 17A shows an apparatus for the beam 1, and FIG.
Shows the actual physical positions of the input fiber 170, the collimating lens 106, and the cylindrical lens 108.
On the other hand, FIG. 17B shows an apparatus for the beam 2, and FIG.
0, the “virtual” positions of the collimating lens 106 and the cylindrical lens 108 are shown. Similarly, FIG.
17 shows an apparatus for the beam 3, and FIG.
(C) shows the input fiber 170 and the collimating lens 10
6 and the “virtual” position of the cylindrical lens 108. As can be seen from FIGS. 17 (A), 17 (B) and 17 (C), the “virtual” position of the previous configuration of the VIPA 76 moves farther from the VIPA 76 for each subsequent interfering light. There will be.

FIGS. 18 (A), 18 (B) and 18 (C)
17A, 17B and 187, respectively.
It is a figure which shows the system equivalent to the system of (C). Change
18 (A), 18 (B), and 18 (C) show
Different lengths L between the lenses ₁, L_TwoAnd L_ThreeIndicates
ing. 18 (A), 18 (B) and 18 (C)
As can be seen, the distance between the lenses is
On the contrary, it will increase. Therefore, for example, number 100
The length of the eye with respect to the interference light (beam 100) is relatively long.
It will be.

Because of the diffraction limit, the collimated light spreads as the distance traveled by the light increases. Thus, light having a very long travel distance, such as beam 100,
Will spread very much. As a result, VIPA cannot cause sufficient interference between various interference lights.

As an example, various thicknesses such as VIPA thickness
For a typical configuration depending on the factors, the L of beam 1₁
Is typically 1 cm. For beam 100
L_{Ten 0}Is typically 20 cm. in this way,
L₁And L₁₀₀Is relatively large. As a result, the beam
100 is too wide to get the right amount of interference
Too much.

If the beam size b ₂ is made larger, this problem is solved by holding the collimated light for a longer distance. However, as described above, FIG.
In the apparatus of (A) and 14 (B) it is often not possible to obtain a sufficiently large beam size b _2.

As an example, assume that beam size b ₂ should be greater than 3 mm, which is the preferred size for typical applications. However, the distances from a ₁ , a ₂ and input fiber 170 to VIPA 76 are generally
Since it is fixed, the maximum allowable focal length f ₁ is 3 mm
Not sufficient to obtain a larger beam size b ₂ it is.

Alternatively, by increasing the size of the device,
It is also possible to obtain mm larger beam size b _2. To obtain the beam size, f ₁ is typically in the range of 2-3 cm. Further, in a typical configuration, a ₂ / a ₁ should be in the range of 3 to 4, f ₂ is substantially 10 cm. Therefore, f ₁ + f ₂ is approximately 13 cm. This total length is often too large. Rather, a more compact device is desired.

FIG. 19A is a side view of an apparatus using VIPA for obtaining a large beam size b ₂ according to an embodiment of the present invention, and FIG. 19B is a front view. FIG.
According to 9 (A) and 19 (B), the device has three lenses 200, 202 and 204 between the input fiber 170 and the VIPA 76. All lenses are preferably cylindrical lenses, semi-cylindrical lenses, or lenses with similar functions. Lenses 200 and 202 have no lens action when viewed from the front.
The lens 204 has no lens function when viewed from the side. The focal length f ₃ is equal to VI
It is as long as the distance to PA76.

In the side view (ie, FIG. 19)
14A), the light is collimated and focused on the VIPA 76 as in the case of FIG.
Therefore, the beam size a ₂ can be arbitrarily determined by selecting just the right numbers for f ₁ and f ₂ .
Further, as shown in the front view (FIG. 19B), the beam size b ₂ can be almost independently determined by the focal length f ₃ .

The devices of FIGS. 19A and 19B are comparable to the devices of FIGS. 14A and 14B. For example, as described above with respect to the apparatus of FIG. 14 (A) and FIG. 14 (B), the in order to obtain a large beam size b ₂ than 3mm must the f ₁ + f ₂ substantially 13cm. On the other hand, in the case of the apparatus shown in FIGS. 19A and 19B, f ₁ + f ₂ is very small, and
It can be much smaller than 3 cm. Further, in FIGS. 19A and 19B, f ₃ is typically about ₂ to 3 cm in order to obtain a beam size b ₂ larger than 3 mm. Therefore, FIG.
The device of FIG. 9 (B) is considerably smaller than the devices of FIGS. 14 (A) and 14 (B).

The above numerical examples merely show general, schematic examples, and do not limit the present invention.
Thus, according to an embodiment of the present invention, the first lens is
It collimates the input light when viewed from the side, and has no lens function when viewed from the front. The second lens is the first lens
When the input light is received from the lens and the input light is collected when viewed from the side and viewed from the front, the lens has no function. The third lens receives the input light from the second lens, collimates the input light when viewed from the front, and has no lens function when viewed from the side. Light from the third lens is received by the VIPA.

Further, the lenses 200 and 202 in FIGS. 19A and 19B can be combined into one lens. For example, FIG. 20A is a side view of an apparatus having two lenses between input fiber 170 and VIPA 76, according to one embodiment of the present invention.
(B) is a front view. According to FIGS. 20A and 20B, the lens 206 acts as a lens when viewed from the side, and has no lens function when viewed from the front. On the other hand, the lens 208 functions as a lens when viewed from the front, and does not have a lens function when viewed from the side.

In various aspects of the above embodiment of the invention, the VIPA directs the resulting light beam to an optical fiber. However, the present invention is also applicable to a VIPA that directs a light beam to another point or an optical element. For example, the present invention provides a method for compensating or generating chromatic dispersion by directing a light beam to a mirror so that light is reflected and returned to the VIPA.
Applicable to an apparatus using IPA.

For example, FIGS. 21 (A) and 21 (B)
FIG. 4 illustrates an apparatus that uses VIPA to compensate or generate chromatic dispersion, according to one embodiment of the present invention.
Referring to FIG. 21A, the light beam generated by the VIPA 76 is collected on the mirror 212 by the lens 210. The mirror 212 reflects and returns the light to the VIPA,
The returned light causes multiple reflections in the VIPA 76,
The output from the IPA 76 is input to the input fiber 170 via the lenses 204, 202, and 200. The device shown in FIG. 21B includes lenses 200, 202, and 20.
The same operation is performed using lenses 206 and 208 instead of 4. For further details of devices using VIPA with optical return devices (such as mirrors), see U.S. Pat.
S. Application 08 / 796,842, "Optical Device Using Virtually Imaged Phased Array to Generate Chromatic Dispersion", and U.S. application Ser. S. Application 08
No./910,251, entitled "Optical Device Using Virtually Imaged Phased Array to Generate Chromatic Dispersion," and is hereby incorporated by reference.

FIGS. 19 (A), 19 (B), 20 (A),
According to 20 (B), 21 (A) and 21 (B), each lens 200, 202, 204, 206, 208 is preferably a cylindrical lens, a semi-cylindrical lens or a one-dimensional graded index lens. is there. However, the invention is not limited to the use of any particular type of lens.

According to the above embodiment of the present invention, VIPA
Includes first and second reflecting surfaces. The second surface has a reflectance such that a part of incident light is transmitted.
VIPA receives input light of each wavelength within a continuous range of wavelengths. The first and second surfaces are arranged such that the input light is reflected multiple times between the first and second surfaces and transmits a plurality of lights through the second surface. The plurality of transmitted lights interfere with each other and are spatially distinguishable from output light generated for input light having any other wavelength within the continuous range of wavelengths (such as light flux 82a or 82b in FIG. 6). ).

According to the above embodiment of the present invention, VIPA
Has been described as being formed by a parallel plate or two reflecting surfaces parallel to each other. However, the plates or reflecting surfaces need not necessarily be parallel.

According to the above embodiment of the present invention, light including a plurality of wavelengths is demultiplexed simultaneously. Therefore, the size of the receiver used for the wavelength multiplex communication can be reduced.

According to the above embodiment of the present invention, VIPA
Can simultaneously demultiplex the wavelength multiplexed light for each wavelength of the input light. Further, the dispersion angle can be adjusted by the thickness t of the parallel plate forming the VIPA. As a result, the dispersion angle can be made large enough so that the receiver can easily receive each of the split signals. For example, a conventional diffraction grating requires a fine uneven surface for a large dispersion angle. However, it is very difficult to provide a fine uneven surface, and the size of the dispersion angle is limited. On the other hand, the VIPA according to the embodiment of the present invention only needs to change the thickness of the parallel plate in order to realize a relatively large dispersion angle.

Further, the VIP according to the above embodiment of the present invention
A produces a larger dispersion angle than a conventional diffraction grating.
Therefore, the receiver using the VIPA according to the embodiment of the present invention can correctly receive an optical signal even in the wavelength multiplexing communication that realizes the high-level multiplexing processing. Furthermore, such a receiver has a relatively simple construction and is relatively inexpensive to manufacture.

According to the above embodiment of the present invention, VIPA
Uses multiple reflections to maintain a constant phase difference between the interfering light beams. As a result, the characteristics of VIPA are stable, and change in optical characteristics due to polarization is suppressed. In contrast, the optical properties of conventional diffraction gratings undergo undesirable changes depending on the polarization of the input light.

Further, compared to the waveguide array grating, the VIPA according to the above embodiment of the present invention achieves stable characteristics and resistance to changes in environmental conditions with a relatively simple configuration.

In the above embodiment of the present invention, the VIP
A has a reflective film for reflecting light. For example, FIG. 7 shows reflective films 122 and 124 for reflecting light.
Is shown. However, VI
PA is not limited to using a "film" to obtain a reflective surface. Rather, the VIPA should simply have a suitable reflective surface, which may or may not be formed of a "film".

Further, in the above embodiment of the present invention,
VIPA includes a transparent glass plate in which multiple reflections occur. For example, FIG. 7 shows a VIPA 76 having a transparent glass plate having a reflective film thereon.
However, VIPA is not limited to using glass members or any type of "plate" to isolate the reflective surface. For example, the reflection surface of VIPA may have a reflection surface that is stably held by a member such as glass or metal having a low thermal expansion, instead of a glass plate, and simply have “air” between them. . Thus, the reflective surface can be described as having a transparent member therebetween, for example, optical glass or air.

While several preferred embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that these embodiments can be used without departing from the principles and spirit of the invention as defined by the appended claims and equivalents thereof. It will be understood that changes can be made to

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional filter using a multilayer interference film.

FIG. 2 is a diagram illustrating a conventional Fabry-Perot interferometer.

FIG. 3 is a diagram showing a conventional Michelson interferometer.

FIG. 4 is a diagram showing a conventional diffraction grating.

FIG. 5 is a diagram showing a conventional waveguide array grating for demultiplexing wavelength division multiplexed light.

FIG. 6 illustrates a virtual imaged phased array (VIPA) according to one embodiment of the present invention.

FIG. 7 illustrates details of the VIPA illustrated in FIG. 6, according to one embodiment of the present invention.

FIG. 8 illustrates a cross section of the VIPA illustrated in FIG. 6 along line VIII-VIII, in accordance with an embodiment of the present invention.

FIG. 9 illustrates interference generated by a VIPA, according to one embodiment of the present invention.

FIG. 10 illustrates a line VIA of the VIPA illustrated in FIG. 6 for determining an inclination angle of input light according to an embodiment of the present invention;
It is a figure showing the section along II-VIII.

FIG. 11 illustrates a VIPA used with a receiver, according to one embodiment of the present invention.

FIG. 12 illustrates a VIPA used with a receiver, according to another embodiment of the present invention.

FIG. 13 shows a waveguide VI according to one embodiment of the present invention.
It is a figure showing PA.

FIG. 14 is a side view and a front view of a device using VIPA, according to one embodiment of the present invention.

FIG. 15 (A) according to one embodiment of the present invention.
FIG. 4 is a simplified side view of FIG.

FIG. 16 illustrates the operation of a VIPA according to one embodiment of the present invention.

FIG. 17 illustrates a first, second, and third embodiment according to one embodiment of the present invention.
FIG. 10 is a diagram showing a front view of an apparatus using VIPA for the third and subsequent interference lights.

FIG. 18 illustrates a system equivalent to the system of FIG. 17, according to one embodiment of the present invention.

FIG. 19 shows a side view and a front view of an apparatus for providing a large beam size in front using VIPA, according to one embodiment of the present invention.

FIG. 20 illustrates a side view and a front view of a device having two lenses between an input fiber and a VIPA, according to one embodiment of the present invention.

FIG. 21 illustrates an apparatus using VIPA to compensate or generate chromatic dispersion, according to one embodiment of the present invention.

[Explanation of symbols]

76 VIPA 78 Focal line 80 Lens 82 Light flux 106 Collimating lens 108 Cylindrical lens 120 Glass plate 122, 124 Reflective film 126 Irradiation window 132 Optical axis 170 Input fiber 200, 202, 204, 206, 208, 210
Lens 212 mirror

Claims (32)

[Claims] An apparatus having a side surface and a front surface for receiving input light of each wavelength within a continuous range of wavelengths, collimating the input light as viewed from the side surface, and having an effect as a lens as viewed from the front surface. A second lens that receives input light from the first lens, converges the input light when viewed from the side, and has no lens effect when viewed from the front; A third lens that receives input light from the lens and collimates the input light when viewed from the front and has no effect as a lens when viewed from the side; and a third lens that has a first and a second surface. The surface has a reflectivity to transmit a part of the incident light, receives input light from the third lens, and the first and second surfaces are configured to receive input light from the first lens.
And a plurality of lights are reflected between the second surface and the plurality of lights are transmitted through the second surface, and the plurality of transmitted lights interfere with each other to emit any other wavelength within the continuous wavelength range. And an angular dispersion device arranged to generate output light that is spatially distinguishable from output light that is also generated for the input light. 2. The first, second, and third lenses converge input light to a converging position in the angular dispersion device, and when viewed from a side, the input light has a corresponding beam size at the converging position. Wherein the first, second and third lenses have focal lengths f ₁ , f ₂ and f ₃ respectively, and the beam size as viewed from the side has a ratio f ₁ / f ₂ Apparatus according to claim 1, characterized in that: 3. The first, second, and third lenses converge input light to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. Wherein the first, second, and third lenses have focal lengths f ₁ , f ₂ , and f ₃ , respectively, and the beam size as viewed from the front is determined by the focal length f ₃ The device of claim 1, wherein 4. The first, second, and third lenses converge input light to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. The first, second, and third lenses have focal lengths f ₁ , f ₂ , and f ₃ respectively, and the beam size as viewed from the front has a ratio f ₁ / f ₂ The device of claim 1, wherein the device is not affected by. 5. The first, second, and third lenses converge input light to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. the has, first, second, and third lenses, each having a focal length f _1, f _2, f _3, a focal length f _3, the beam size is 3mm or more when viewed from the front The apparatus of claim 1, wherein the length is such that 6. The apparatus according to claim 1, wherein said first, second, and third lenses linearly converge input light between said first and second surfaces of said angular dispersion device. The described device. 7. The input light is wavelength division multiplexed light composed of at least two carriers each having a different wavelength within a continuous range of wavelengths. A plurality of transmitted lights interfere with each other and are spatially separated from other output lights. The apparatus according to claim 1, wherein each output light that can be distinguished is generated for each carrier of the input light. 8. The apparatus according to claim 1, wherein each of said first, second, and third lenses is one of a group consisting of a cylindrical lens, a semi-cylindrical lens, and a one-dimensional graded index lens. An apparatus according to claim 1. 9. A device having a side surface and a front surface for receiving input light of each wavelength within a continuous range of wavelengths, collimating the input light as viewed from the side surface, and having an effect as a lens as viewed from the front surface. A second lens that receives input light from the first lens, converges the input light when viewed from the side, and has no lens effect when viewed from the front; A third lens that receives the input light from the lens, collimates the input light when viewed from the front, has no lens effect when viewed from the side, and therefore converges the input light to a line; A second surface having a reflectivity for transmitting a part of the incident light; and a first and a second surface having an input light from the third lens. Emanating from the line, reflected multiple times between the first and second surfaces, transmitting a plurality of light through the second surface, Transmitted light interfere with each other to generate output light that is spatially distinguishable from output light generated for input light of different wavelengths. And equipment. 10. The first, second and third lenses,
The input light converges to a converging position in the angular dispersion device, and when viewed from the side, the input light has a corresponding beam size at the converging position. The first, second, and third lenses are , each having a focal length _{f 1, f 2, f 3} , the beam size as seen from the side, according to claim 9, characterized in that it is determined by the ratio f ₁ / f _2. 11. The first, second, and third lenses,
The input light converges to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. The first, second, and third lenses , each having a focal length _{f 1, f 2, f 3} , the beam size as seen from the front, according to claim 9, characterized in that it is determined by the focal length f _3. 12. The first, second, and third lenses,
The input light converges to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. The first, second, and third lenses , each having a focal length _{f 1, f 2, f 3} , the beam size as seen from the front, according to claim 9, characterized in that not affected by the ratio f ₁ / f _2. 13. The first, second and third lenses,
The input light converges to a converging position in the angular dispersion device, and when viewed from the front, the input light has a corresponding beam size at the converging position. The first, second, and third lenses are The focal lengths f ₁ , f ₂ , and f ₃ , respectively, wherein the focal length f ₃ is such that the beam size is 3 mm or more when viewed from the front. apparatus. 14. The apparatus according to claim 9, wherein said first, second and third lenses linearly converge input light between said first and second surfaces of said angular dispersion device. The described device. 15. The input light is wavelength division multiplexed light comprising at least two carriers each having a different wavelength within a continuous range of wavelengths, and a plurality of transmitted lights interfere with each other;
The apparatus according to claim 9, wherein each output light that is spatially distinguishable from other output light is generated for each carrier of the input light. 16. The system of claim 1, wherein each of the first, second, and third lenses is one of a group consisting of a cylindrical lens, a semi-cylindrical lens, and a one-dimensional graded index lens. Device according to claim 9. 17. A device having a side surface and a front surface for receiving input light of each wavelength within a continuous wavelength range, receiving the input light, acting as a lens when viewed from the side, and a lens when viewed from the front. A first lens having no effect as described above, a second lens receiving input light from the first lens, acting as a lens when viewed from the front, and having no effect as a lens as viewed from the side, A first surface and a second surface, the second surface having a reflectivity for transmitting a part of incident light, receiving input light from the second lens, and receiving the first and second surfaces. Of the input light is the first
And a plurality of lights are reflected between the second surface and a plurality of lights are transmitted through the second surface, and the plurality of transmitted lights interfere with each other to emit any other wavelength within a continuous range of wavelengths. An angular dispersion device arranged to generate spatially distinguishable output light from output light generated for the input light. 18. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, the beam size as seen from the front, according to claim 17, characterized in that it is determined by the focal length f _2. 19. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, the beam size as viewed from the front, according to claim 17, characterized in that not affected by the focal length f _1. 20. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, claim the focal length f ₂ is characterized by beam size when viewed from the front is the length such that 3mm or more 17
An apparatus according to claim 1. 21. The apparatus according to claim 17, wherein said first and second lenses linearly converge input light between said first and second surfaces of said angular dispersion device. . 22. The input light is a wavelength division multiplexed light composed of at least two carriers each having a different wavelength within a continuous range of wavelengths, a plurality of transmitted lights interfere with each other,
18. The apparatus according to claim 17, wherein each output light that is spatially distinguishable from other output light is generated for each carrier of the input light. 23. The apparatus according to claim 17, wherein each of the first and second lenses is one of a group consisting of a cylindrical lens, a semi-cylindrical lens, and a one-dimensional graded index lens. Equipment. 24. A device for receiving input light, having a side surface and a front surface, wherein the device receives the input light, acts as a lens when viewed from the side, and has no effect as a lens when viewed from the front. A second lens that receives input light from the first lens, acts as a lens when viewed from the front, has no lens effect when viewed from the side, and thus converges the input light to a line; A first surface and a second surface, wherein the second surface has a reflectivity for transmitting a part of incident light, and the first and second surfaces have a reflectance from the second lens. Input light is emitted from the line and is reflected multiple times between the first and second surfaces, a plurality of lights are transmitted through the second surface, and the plurality of transmitted lights interfere with each other. Angle components arranged to produce spatially distinguishable output light from output light generated for input light of different wavelengths. Device characterized in that it comprises apparatus and, a. 25. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, the beam size as seen from the front, according to claim 24, characterized in that it is determined by the focal length f _2. 26. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, the beam size as viewed from the front, according to claim 24, characterized in that not affected by the focal length f _1. 27. The first and second lenses converge input light to a converging position in the angular dispersion device, and the input light has a corresponding beam size at the converging position when viewed from the front. The first and second lenses have a focal length f ₁ ,
has f _2, a focal length f ₂ is claim wherein the beam size when viewed from the front is the length such that 3mm or more 24
An apparatus according to claim 1. 28. The apparatus according to claim 24, wherein said first and second lenses linearly converge input light between said first and second surfaces of said angular dispersion device. . 29. The input light is wavelength division multiplexed light comprising at least two carriers each having a different wavelength within a continuous range of wavelengths, wherein a plurality of transmitted lights interfere with each other,
26. The apparatus of claim 24, wherein each output light is spatially distinguishable from the other output light for each carrier of the input light. 30. The apparatus according to claim 24, wherein each of the first and second lenses is one of a group consisting of a cylindrical lens, a semi-cylindrical lens, and a one-dimensional graded index lens. Equipment. 31. A device for receiving input light of each wavelength within a continuous range of wavelengths having a side surface and a front surface, wherein the device receives the input light, converges the input light when viewed from the side, and when viewed from the front. A first lens having no lens effect, receiving input light from the first lens, collimating the input light when viewed from the front, and having no lens effect when viewed from the side; A second lens for condensing light into a line; a first lens and a second surface, the second surface having a reflectivity for transmitting a part of incident light, The first and second surfaces receive input light from a lens, and the first and second surfaces are coupled to the first light.
And a plurality of lights are reflected between the second surface and a plurality of lights are transmitted through the second surface, and the plurality of transmitted lights interfere with each other to emit any other wavelength within a continuous range of wavelengths. An angular dispersion device arranged to generate spatially distinguishable output light from output light generated for the input light. 32. An apparatus having a side surface and a front surface for receiving input light of each wavelength, wherein the device receives the input light, converges the input light when viewed from the side, and has an effect as a lens when viewed from the front. A first lens having no lens, receiving the input light from the first lens, collimating the input light as viewed from the front, and collecting the input light as a line without the lens effect as viewed from the side. A second lens that emits light, a first surface and a second surface, wherein the second surface has a reflectivity for transmitting a portion of incident light, and the first and second surfaces are The input light is reflected multiple times between the first and second surfaces;
A plurality of lights are transmitted through the second surface, the plurality of transmitted lights interfering with each other to produce output light spatially distinguishable from output light generated for input light having different wavelengths. An angular dispersion device arranged to generate.