WO2003005086A1

WO2003005086A1 - Asymmetric arrayed waveguide grating device

Info

Publication number: WO2003005086A1
Application number: PCT/CN2001/001158
Authority: WO
Inventors: Sailing He
Original assignee: Hangzhou Coer Photonic Information Technologies Ltd.
Priority date: 2001-07-06
Filing date: 2001-07-06
Publication date: 2003-01-16
Also published as: CN1227548C; CN1524191A

Abstract

An asymmetric arrayed waveguide grating (AWG) device mainly includes an input-side coupler, arrayed waveguide and an output-side coupler, in which a non-circle arc edge between a free-space region in the input-side coupler and the arrayed waveguides is optimized; and the distance from an input waveguide to arrayed waveguide imports, the widths and the intervals of the imports are varied, so that the light intensity received by each waveguide in AWG has a certain distribution, reaching the highest general coupling efficiency, and the lengths of the arrayed waveguide have been adjusted, and field distribution at the connection of free-space region and the arrayed wave-guide in the out-side coupler is conformed to the predetermination that is sinc function divided by a guassian function, i.e. channel frequency spectral response having flat top and steep edge.

Description

Asymmetric array waveguide grating device TECHNICAL FIELD

The present invention relates to an asymmetric arrayed waveguide grating (AWG) device, and more particularly, to an asymmetric arrayed waveguide grating device having an optimal spectral passband response and minimum loss. Background technique

Wavelength division multiplexing (demultiplexing) devices and routers are key components in optical communication networks. Among them, arrayed waveguide grating (AWG) devices have been widely used in wavelength division multiplexing (WDM) systems. A problem with the traditional type of AWG wavelength division multiplexing device is that its frequency band has a sharp peak shape, that is, it has the maximum transmission rate at the center wavelength, and when the wavelength is offset from this center wavelength, it passes The rate will drop rapidly. In this way, the wavelengths of all optical signals in the optical network must be very accurate to avoid degradation of system performance. This has led to stringent requirements for the design and operation of the entire optical network and its components.

Devices that combine light of different wavelengths into one beam of light and separate one beam of composite light into different wavelengths of light are called multiplexers (multiplexers) and demultiplexers (demultiplexers). Generally, the same An AWG can serve as both a multiplexer and a demultiplexer. The only difference is that the direction of light passing through the device is opposite. For convenience, only the demultiplexer is described below. The present invention is also applicable to multiplexers.

When an AWG device is used as a demultiplexer, it consists of an input waveguide, a first star coupler (input coupler), an array waveguide with an optical path difference between adjacent waveguides, and a second star coupler (output coupler). And multiple output waveguides; each output waveguide receives light of a different wavelength, the first star coupler couples the input composite light into the array waveguide, and the dispersion function of the array waveguide grating for different wavelengths makes the first waveguide After the two-star coupler, different wavelengths of light are focused on different output waveguides.

In many applications, the input and output waveguides of AWG devices are single-mode. The lateral optical field distribution of the input and output waveguides can usually be approximated by a Gaussian function. At the center wavelength, the input field distribution is imaged on the output waveguide by AWG. If the center of the image field distribution and the mode field distribution of the output waveguide are aligned, then we can get the maximum coupling efficiency. When the wavelength deviates from the center wavelength, the center of the image field distribution and the mode field distribution of the output waveguide will also shift, so that the coupling efficiency will decrease accordingly. The overlapping integration of the two mode field distributions determines the channel's spectral response. This response is approximately a Gaussian function.

The ideal shape of the spectrum response is a rectangular function. The flatter the top of the response curve, the better. This can increase the bandwidth of each channel as much as possible and reduce the light intensity change in this passband. At the same time, both sides of the spectrum curve It should be as steep as possible to reduce crosstalk between two adjacent channels.

Several techniques have been used to improve the shape of the spectral response. US Patent No. 5412744 discloses one: "Frequency routing device having a wide and substantially flat passband." The patent provides a method for flattening the spectral response. In this method, the light received by two adjacent output waveguides is recombined by using a Y-shaped connector. In this method, To maintain the required level of crosstalk, there must be extra space between adjacent pairs of output waveguides. The number of channels and channel bandwidth that this device can obtain is severely limited.

In another article entitled: "flattening the spectral response of a phased array demultiplexer" (A phased- array wavelength demultiplexer with flattened wavelength response), of:. M. R Amersfoort et al., Published in "Electronics Letters" (Electronics, Lett.) Volume 30, No. 4, 1994 article, using a multimode output waveguide to flatten the spectral response, it is possible to connect the multimode output waveguide to the detector in the receiver, but this device It cannot be used to route signals of different wavelengths in a single-mode optical network.

U.S. Patent No. 6141152, discloses a "Multiplexer / Demultiplexer with flattened spectral response" patent, which uses multiple-grating-circle in the AWG ) Design, so that multiple input mode field distribution images are projected onto the output waveguide. In this way, the comprehensive spectral response can be flattened and the passband widened, but the two edge portions of the spectral response curve cannot be obtained. Improvement, and insertion loss will also increase significantly.

In another article entitled: "Array Waveguide Grating Combiner with Flattened Spectrum Response"

(Arrayed - waveguide grating multiplexer with flat spectral response) of the article, the authors:. K. Okamoto, Η Yamada, published in "Optics Letters," Vol 20, No l pp 3-45, 1995 (Optics Lett.).. According to the distribution of the sine function, the phase and amplitude of the AWG are changed to flatten the spectral response. The amplitude distribution is achieved by changing the waveguide aperture on the interface of the first stripe array. The main disadvantage is the severe increase in insertion loss due to the low coupling efficiency in the first coupler.

In another article entitled: "Application of the principle that the Fourier spectrum of a phased array of optical wavelength router response flatness design and simulation," OF: N. Kim, Y. Chung, published in "Integrated Optics Research Collection" (Proceeding of Integrated Photonics Research), IWAl p. 361-363, 1998, according to the distribution of the sine function, the amplitude distribution on the AWG strip waveguide interface is adjusted in the second star coupler, which is the same as the method of Okamoto mentioned above similar. The amplitude distribution is achieved by introducing different losses through each waveguide in the AWG. This method of amplitude adjustment is very difficult to control in actual operation, and it will also seriously increase the insertion loss and crosstalk of the device.

Figure 1 shows a conventional arrayed waveguide grating. The free transmission region 20 is connected to a plurality of input waveguides I _k (k = 1, 2,, -N), the array waveguide 30 is connected to the free transmission region 20 and the free transmission region 40, and the free transmission region 40 is connected to a plurality of output waveguides 0 _k ( k = l, 2, ...,! are connected. Each of the waveguides in the arrayed waveguide 30 has a different length, and a corresponding optical path difference is generated between adjacent waveguides, thereby achieving a similar function to a grating. This device can be used as a complex For example, when this device is used as a demultiplexer, a composite optical signal containing multiple wavelengths is coupled to one of the input waveguides, and each wavelength channel is separated and focused by the array waveguide grating. Each output waveguide.

Although only one input waveguide is required in the demultiplexing process, in order to be able to select and use different input waveguides, multiple input waveguides are usually designed. Select different input waveguides The channel wavelength of the output waveguide can be changed. If used as a wavelength router (such as NX N), multiple inputs and outputs are used simultaneously. Therefore, similar to the star coupler on the output side, the free transmission area in the star coupler on the input side and the array waveguide at the interface of the array waveguide grating must be arranged on an arc at equal intervals. Therefore, even if the input waveguide is different from the output waveguide in terms of width, pitch, number, etc. in some designs, the arrayed waveguide grating 30 itself is substantially symmetrical.

However, for most demultiplexed applications, only one input waveguide is required. In this case, the first star coupler is equivalent to a 1 X N beam splitter. Therefore, at the interface between the free transmission area of the first star coupler and the arrayed waveguide grating, the arrayed waveguide does not need to be arranged at equal intervals, nor does it need to be on an arc. With these additional degrees of freedom, other properties of the star coupler can be further optimized, such as generating a certain field distribution at the array waveguide and obtaining the maximum total coupling efficiency at the same time. In addition, by combining with the phase adjustment in the array waveguide, You can get a desired spectral response with minimal loss. Disclosure of invention

The main purpose of the present invention is to provide an asymmetric arrayed waveguide grating device. By designing an asymmetric AWG device, the frequency spectrum can be flattened accordingly, the passband can be widened, and the insertion loss and crosstalk of the device can be reduced.

To achieve the purpose of the present invention, we propose an asymmetric array waveguide grating device. The design of the output coupler is similar to the traditional AWG design (that is, the tail ends of the AWG are evenly arranged along the circumference), and the input coupler and its The design of the waveguide tail is different, so devices designed in this way are generally asymmetric.

We propose an asymmetric arrayed waveguide grating device whose composition includes:

At least one input waveguide, which transmits multiple composite signals of different wavelengths;

An input beam splitting coupler connected to the input waveguide and receiving a composite signal from the input waveguide;

An array waveguide grating, which is composed of a plurality of waveguides of different lengths, and is connected with the input Beam splitter connection;

A star-shaped focusing coupler connected to the arrayed waveguide grating, which converts the role dispersion of signals of different wavelengths into a spatial displacement dispersion with a focus line;

A plurality of output waveguides coupled with the star-shaped focusing coupler, and the tail ends of the output waveguides are arranged on the focusing lines of the star-shaped focusing coupler and respectively transmit optical signals of different wavelengths;

The input beam splitting coupler connects the arrayed waveguide grating and the input waveguide. The tail ends of the waveguides of the arrayed waveguide grating are not arranged at equal intervals along the circumference. The coupling coefficient is a predetermined distribution function.

In the asymmetric arrayed waveguide grating device, the junction between the arrayed waveguide and the input beam splitting coupler at the input end has a different distance between the position of the tail end of each waveguide and the tail end of the input waveguide.

In the asymmetric arrayed waveguide grating device, in the arrayed waveguide grating, a connection end of each waveguide and an input beam splitter coupler has a different entrance width.

The asymmetric arrayed waveguide grating device, wherein in the arrayed waveguide grating, there is a different waveguide center to waveguide center distance between each waveguide and the connection end of the input beam splitting coupler, so that the total coupling Maximum efficiency.

In the asymmetric arrayed waveguide grating device, in the arrayed waveguide grating, a connection end of each waveguide is located on a circular arc centered at an end of an input waveguide, but has different entrance widths and different waveguides. The center distance, so that the energy of each waveguide coupled to the arrayed waveguide grating has a predetermined distribution function, while maximizing the total coupling efficiency.

In the asymmetric array waveguide grating device, the input beam splitting coupler is a multi-stage 1 × 2 Y-waveguide input beam splitting coupler.

The asymmetric arrayed waveguide grating device, wherein the multi-stage input beam splitter coupler is an asymmetrical Y-waveguide coupler with an unbalanced coupling coefficient, so that each of the arrayed waveguide gratings coupled to the arrayed waveguide grating is coupled. The energy of the waveguide has a predetermined distribution function. In the asymmetric array waveguide grating device, the amplitude coupling coefficient between the input waveguide and each waveguide of the array waveguide grating is adjusted so that the field distribution at the connection between the output coupler and the array waveguide has a predetermined The distribution function is such that the top of the spectral response curve of each channel is flat enough and the edges are sharp enough.

In the asymmetric arrayed waveguide grating device, the predetermined distribution function is a sine function divided by a Gaussian function, and the sine function is basically consistent with a desired inverse Fourier transform of a spectral response function, and the The Gaussian function is basically the same as the inverse Fourier transform of the mode field distribution function of the output waveguide, which corresponds to the optical properties of the focused star coupler.

The asymmetric arrayed waveguide grating device, wherein the length of each waveguide of the arrayed waveguide grating is to be adjusted, except that an adjacent phase difference between an integer multiple of 2 π of a given channel wavelength is generated between adjacent waveguides. In addition, the phase difference introduced by the above-mentioned coupler must be compensated, and in these waveguides, the π phase shift required when the field distribution function at the connection between the predetermined output coupler and the array waveguide is negative is generated.

Another asymmetric arrayed waveguide grating device includes:

'An input beam splitter coupler connected to the input waveguide and receiving a composite signal from the input waveguide;

An array waveguide grating, which is composed of a plurality of waveguides of different lengths, and is connected to the input beam splitting coupler;

It also includes an optical attenuator or amplifier, which is used in at least a part of the waveguides of the arrayed waveguide grating, which are in combination with the input waveguide and the waveguide of the arrayed waveguide grating. The combination of the coupling coefficients results in a certain light intensity distribution function at the interface between the arrayed waveguide grating and the focusing star coupler at the output end. This light intensity distribution function is equal to a sinc_function divided by a Gaussian function, thereby obtaining a Steep channel spectral response curve on both flat sides.

In the asymmetric array waveguide grating device, the sine function is obtained by performing an inverse Fourier transform on a desired spectral response, and the Gaussian function is an inverse Fourier transform of a mode field distribution of a single-pass chirped output waveguide. Obtained, and the Fourier transform corresponds to the optical properties of the focusing star coupler.

The asymmetric arrayed waveguide grating device, wherein the length of each waveguide of the arrayed waveguide grating is to be adjusted, except that an adjacent phase difference between an integer multiple of 2 π of a given channel wavelength is generated between adjacent waveguides. The phase difference introduced by the input beam splitting coupler must be compensated, and in some waveguides, the field distribution function at the connection between the predetermined output coupler and the array waveguide is negative (required at all times) π phase shift.

FIG. 1 is a schematic diagram of a conventional AWG wavelength division multiplexing device corresponding to the prior art; FIG. 2 (a) is a schematic diagram of an asymmetric AWG wavelength division multiplexing device according to an embodiment of the present invention; FIG. 2 (b) is a diagram Enlarged drawing of the star coupler at the input in 2a;

3 is an enlarged view of an input star coupler according to another embodiment of the present invention; FIG. 4 is an enlarged view of an input multistage separator of another embodiment of the present invention; FIG. 5 is a conventional AWG in a coupler free Field distribution at the junction of the transmission region and the AWG; Figure 6 (a) is an amplitude distribution diagram of the junction between the free transmission region in the coupler and the AWG of the AWG device according to a specific embodiment of the present invention;

FIG. 6 (b) is a phase distribution of an AWG device in a specific embodiment of the present invention at the connection between the free transmission area in the coupler and the AWG. The phase term is excluding the conventional phase difference 2im π. FIG. 7 is FIG. 6 The simulation results of the spectral response of the AWG device are compared with those of the traditional AWG. The best way to implement the invention

The following further describes the asymmetric arrayed waveguide grating wavelength division multiplexing device provided by the present invention with reference to the drawings as follows:

FIG. 2 (a) is a schematic diagram of an asymmetric AWG device according to the first embodiment of the present invention. The design of the output coupler is similar to the traditional AWG design (that is, the tail ends of the AWG have the same width and are arranged uniformly along the circumference) The design of the input coupler is very different. Figure 2 (b) is an enlarged view of the input star coupler in Figure 2 (a). The free transmission area in the input coupler and the contact line of the array waveguide are an optimized curve (such as a sine function) instead of a circular arc. The distance from the input waveguide to the array waveguide entrance, as well as the waveguide entrance width, varies, so that the light energy received by each waveguide in the AWG varies according to a predetermined function. The spacing between the waveguides is also adjusted and changed to maximize the total coupling efficiency. The length of the AWG's waveguide is also adjusted so that the distribution of the complex field (including amplitude and phase) at the connection between the free transmission area in the output coupler and the AWG is consistent with the predetermined one, so that the desired output channel can be obtained The obtained spectral response.

FIG. 3 is an enlarged view of an input-side star coupler in a second embodiment of the present invention; the connection point between the free transmission area in the input coupler and the AWG is on the circumference centered on the tail of the input waveguide. It is similar to the traditional AWG. However, the waveguide entrance width of the input star coupler and the waveguide center distance (at the point where the free transmission area in the input coupler and the array waveguide contact) are adjusted and changed to enable the expected total coupling efficiency Amplitude distribution. Compared with the input star coupler designed by Okamoto and H. Yamada in the article (Optics Lett. 20, p43-45, 1995), the center-to-center spacing between adjacent waveguides at the junction of the free transmission area and AWG is no longer constant It is adjusted together with the waveguide entrance width. If the device is operated in the opposite direction, the wavelength dispersion characteristics of the AWG will be lost. However, when the device operates in the designed light propagation direction, this degree of freedom allows the coupling efficiency to be maximized while the waveguide entrance width is changed.

It should be noted that although this device cannot be used in reverse as a demultiplexer, it can be used in reverse as a multiplexer due to the reversible nature of the optical path. Figure 4 shows a third embodiment of the present invention; in order to obtain the expected amplitude distribution with maximum coupling efficiency, the star coupler is replaced with a multi-stage beam splitter (such as a 1 X 2 Y beam splitter ). The beam splitting ratio of the coupler is designed according to the intensity distribution required by the array waveguide. In principle, a high coupling efficiency can be obtained because there is no loss other than the loss caused by manufacturing defects.

Unlike the star-shaped coupler, where the waveguides are evenly arranged on a circular arc, the coupler / beam splitter in the present invention introduces phase differences for different paths. These optical path differences must be compensated by adjusting the waveguide length in the AWG. Coupler The combination of the / beamsplitter and AWG must produce a predetermined intensity and phase distribution at the interface of the second (ie, output) star coupler's AWG and planar slab waveguide.

As an important embodiment of the present invention, in order to make the top of the channel's spectral response curve relatively flat and the edges relatively steep, the field distribution at the connection between the free transmission area in the second star coupler and the AWG should be basically one The sine function is divided by a Gaussian function. This sine function is basically the same as the inverse Fourier transform of the desired spectral response function, and this Gaussian function is basically the same as the inverse Fourier transform of the mode field distribution function of the output waveguide. The Fourier transform is produced by the optical properties of a focused star coupler.

Suppose we want to get the spectrum response function of a rectangular function

S (X) = rect (^^-) (1)

Where is the center wavelength of a channel, and Δλ is the desired spectrum width of the channel. If the convolution effect of the mode field distribution function of the output waveguide is not considered first, the field distribution on the output waveguide plane corresponding to the spectral response function is

A (x) = rec ^-) (2)

Δχ

Where X is the coordinate on the plane of the output waveguide, Δχ = βΔλ, β = — is the grating of the grating

Dispersion constant. In order to obtain the field distribution on the plane of the Hannout waveguide, the output of the star coupler

The field distribution at the AWG interface should be the inverse Fourier transform of A (x), that is, ux

A _g (u) = 丄_∞ iln

A (x) e dx

Where _{M =} , n is the effective refractive index of the planar waveguide and is the length of the output star coupler

XL

Degree, X is the coordinate at the interface between the AWG grating and the output star coupler. When A (x) is a rectangular function (we take the central output waveguide as an example, that is, c _e = 0), A _g (u) is a sine function, ie

So without considering the convolution effect of the touch field distribution function of the output waveguide, the field distribution at the interface between the AWG grating and the output star coupler can be written as

Let us now consider the convolution effect of the mode field distribution function of the output waveguide. Since the spectral response function corresponds to the convolution of the field distribution on the output waveguide plane and the mode field distribution function of the output waveguide, in order to obtain a spectral response close to a rectangular function, the field distribution on the output waveguide plane A

(x) The equation to be satisfied is changed from equation (2) to

A (x) ® G (x) = recti ^^-) (6)

Ax

Where G (x) is the normalized mode field distribution function of the output waveguide, which can generally be approximated as a Gaussian function. G (X) can be expressed as

Where w _Q is the beam waist width of the Gaussian mode field distribution.

By inverse Fourier transform of equation (6), we can get

Where G _g (u) is the inverse Fourier transform of G (x), ie

G _g (u) = [ _∞ G (x) e ^i23rux dx

Substituting „= into (9), we get G (x ') = G ^) = (2. ² ) ^{J iLJ¾} ^ (10) This is actually the far-field distribution function of the output waveguide mode at the AWG interface of the output star coupler. It is also a Gaussian function. Its waist width is w = ^ ~. So equation (5) can be modified as

., ,, XL sin (πβ Αληχ '/ XL)

s πηχ ^l G (x ^{ )

K. Okamoto and H. Yamada entitled "Arrayed Waveguide Grating Multiplexer with Flat Spectral Response" and N. Kim and Y. Chung entitled "Using Fourier Optics Concept for Phased Array Wavelength Router with Flat Response In the design and simulation paper, the intensity and phase distribution of the AWG is adjusted according to a sine function distribution. In this case, the field distribution on the output waveguide plane is basically similar to a rectangular function. However, the shape of its spectral response curve is basically equal to the convolution of this field distribution and mode field distribution (basically Gaussian). This results in slow slope changes on both sides of the spectral response curve, although the bandwidth is broadened and flattened.

By adjusting the field distribution at the 'AWG' interface of the output star coupler by dividing the sine function by a Gaussian function, the channel photophonic response (rather than the field distribution of the output plane) basically becomes a rectangular function. So this result is much better than the previous method.

As a specific design example, we selected the following design parameters:

The length of the free propagation zone L = 4950.355um,

Effective refractive index ns = l.468 in the free propagation region,

Waveguide effective refractive index nwg = l.465,

The center wavelength is 1.55um,

Channel frequency interval Af = 100GHz,

0.7ηηι, (Δλ is the width of the passband spectrum we want to obtain),

Number of array grating stages m = 72,

Number of arrayed grating waveguides N = 141,

Equivalent Gaussian beam waist radius w0 = 4.25um, The center distance between AWG waveguides is d = 8.um,

The center distance between the receiving waveguides is 24.305 um,

Figure 5 shows the Gaussian intensity distribution of the conventional AWG at the interface between the AWG of the output star coupler and the planar slab waveguide.

Fig. 6a is an example of the intensity distribution at the interface between the AWG of the output star coupler and the planar slab waveguide according to an important embodiment of the present invention. Fig. 6b is the corresponding phase distribution. The phase term is added to the ordinary 2im 7r. i = 1, 2, 3, ~ M, M is the number of waveguides of the AWG, m is the number of grating stages, it should be noted that the negative sign of the sine function corresponds to a 7T phase factor.

Figure 7 is the simulated spectral response (solid line) of the AWG example we designed in Figure 6, and the traditional AWG spectral effect (dashed line) is added for comparison. We find that the top of the spectral response curve is widened and flattened, while the edges on both sides become steeper. -As listed earlier, we can implement the field distribution of the sine function divided by a Gaussian function (ie, formula (1 1)) at the AWG interface of the output star coupler in various ways. For example, we know that the different funnel design parameters (such as the opening width) of each waveguide entrance of AW G will correspond to different coupling coefficients. We can draw the relationship between the coupling coefficient and the opening width of the funnel. Therefore, we only need to adjust the width of the funnel opening of the array waveguide at different positions to obtain the required coupling coefficient distribution. To achieve the field distribution of formula (1 1) at the AWG interface of the output star coupler, the coupling coefficient distribution at the input of the AWG should be the formula (1 1) divided by a Gaussian function Gl (x), where Gl (x) Field distribution at the entrance of the array waveguide when the fundamental mode is input from the center input waveguide.

Changes and adjustments can be made to the invention without departing from the spirit of the invention. In general, some features of the present invention can also be used without using other features. For example, the field distribution can be optimized for other purposes than spectrum flattening. Therefore, what is done within the spirit of the present invention Obvious changes should be included in the protection scope of the invention. Industrial applicability

To sum up, the asymmetric arrayed waveguide grating device we have proposed optimizes the input beam splitter coupler according to different functions so that it becomes an asymmetrical arrayed waveguide grating. The asymmetrical arrayed waveguide grating has a flat spectral response and a passband. It is wider, and the insertion loss and crosstalk of the device are reduced.

Claims

Profit requirements

1. An asymmetric arrayed waveguide grating device, comprising:

An array waveguide grating, which is composed of a plurality of waveguides of different lengths, is connected to the input beam splitting coupler, and outputs a plurality of monochromatic lights of different wavelengths;

Multiple output waveguides, which are coupled to the star-shaped focusing coupler, and the tail ends of the output waveguides are arranged on the focusing lines of the star-shaped focusing coupler and respectively transmit optical signals of different wavelengths;

It is characterized in that the input beam splitting coupler connects the arrayed waveguide grating and the input waveguide, the tail ends of the waveguides of the arrayed waveguide grating are not arranged at equal intervals along the circumference, and each of the input waveguide and the arrayed waveguide grating The coupling coefficient between waveguides is a predetermined distribution function.

2. The asymmetric array waveguide grating device according to claim 1,

It is characterized in that at the junction of the array waveguide and the input beam splitting coupler, the position of the tail end of each waveguide and the tail end of the input waveguide are different from each other.

3. The asymmetric array waveguide grating device according to claim 2,

It is characterized in that in the arrayed waveguide grating, the connection end of each waveguide and the input beam splitter coupler has a different entrance width.

4. The asymmetric array waveguide grating device according to claim 3,

It is characterized in that in the arrayed waveguide grating, there is a different waveguide center to waveguide center distance between each waveguide and the connection end of the input beam splitting coupler, so as to maximize the total coupling efficiency.

5. The asymmetric array waveguide grating device according to claim 1,

It is characterized in that in the arrayed waveguide grating, the connection end of each waveguide is located on a circular arc centered at the end of the input waveguide, but has different entrance widths and different center distances between the waveguides, so that coupling to The energy of each waveguide of the arrayed waveguide grating has a predetermined distribution function while maximizing the total coupling efficiency.

6. The asymmetric array waveguide grating device according to claim 1,

It is characterized in that the input beam splitting coupler is a multi-stage 1x2 Y-waveguide input beam splitting coupler.

7. The asymmetric array waveguide grating device according to claim 6,

It is characterized in that the multi-stage input beam splitting coupler is an asymmetric Y-waveguide coupler and has an unbalanced coupling coefficient, so that the energy of each waveguide coupled to the arrayed waveguide grating has a predetermined value. Distribution function.

8. The asymmetric array waveguide grating device according to claim 1,

It is characterized in that the amplitude coupling coefficient between the input waveguide and each waveguide of the arrayed waveguide grating is adjusted so that the field distribution at the connection between the output coupler and the arrayed waveguide has a predetermined distribution function, so that each The top of the channel's spectral response curve is flat enough and the edges sharp enough.

9. The asymmetric array waveguide grating device according to claim 8,

It is characterized in that the predetermined distribution function is a sine function divided by a Gaussian function, the sine function is basically consistent with the inverse Fourier transform of the required frequency response function, and the Gaussian function is basically the same as the output The inverse Fourier transform of the mode field distribution function of the waveguide is the same, and this Fourier transform corresponds to the optical properties of the focused star coupler.

10. The asymmetric array waveguide grating device according to claim 9,

It is characterized in that the length of each waveguide of the arrayed waveguide grating needs to be adjusted, in addition to generating a phase difference equal to an integer multiple of 2 π of a given channel wavelength between adjacent waveguides, it is also necessary to compensate for the above coupling. The phase difference introduced by the filter, and in these waveguides, the required field distribution function at the connection between the predetermined output coupler and the array waveguide is generated when the field distribution function is negative. Phase shift.

11 .. An asymmetric arrayed waveguide grating device, comprising:

An array waveguide grating, which is composed of a plurality of waveguides of different lengths, and is connected to the input sub-coupler;

Multiple output waveguides, which are coupled with the star-shaped focusing coupler, and the tail ends of the output waveguides are arranged on the focusing lines of the star-shaped focusing coupler, and respectively transmit optical signals of different wavelengths,

It is characterized in that the input beam splitting coupler is connected to the arrayed waveguide grating and the input waveguide, and the coupling coefficient between each waveguide of the input waveguide and the arrayed waveguide grating has a certain distribution, so that the output coupler and the The field distribution at the connection of the array waveguide is a sine function divided by a Gaussian function to obtain the flat top and steep edges of the spectral response curve.

12. The asymmetric arrayed waveguide grating device according to claim 11, wherein the sine function is obtained by inverse Fourier transform of a desired spectral response, and the Gaussian function is for a single channel. The mode field distribution of the output waveguide is obtained as an inverse Fourier transform, and the Fourier transform corresponds to the optical properties of the focused star coupler.

13. The asymmetric array waveguide grating device according to claim 12,

It is characterized in that the length of each waveguide of the arrayed waveguide grating needs to be adjusted, in addition to generating a phase difference equal to an integer multiple of 2 π of a given channel wavelength between adjacent waveguides. The phase difference introduced by the input splitter coupler, and in some waveguides, produces the pre-determined π phase shift required when the field distribution function at the connection between the output star focus coupler and the array waveguide is predetermined.

14. The asymmetric array waveguide grating device according to claim 13, It is characterized in that at the junction of the array waveguide and the input beam splitting coupler, the position of the tail end of each waveguide and the tail end of the input waveguide have different distances.

15. The asymmetric array waveguide grating device according to claim 13,

16. The asymmetric array waveguide grating device according to claim 15,

It is characterized in that in the arrayed waveguide grating, there is a different waveguide center-to-center distance between each waveguide and the connection end of the input beam splitting coupler, so that the total coupling efficiency is maximized.

17. The asymmetric array waveguide grating device according to claim 13,

18. The asymmetric array waveguide grating device according to claim 13,

It is characterized in that the input beam splitting coupler is a multi-stage 1x2 Y-waveguide input beam splitting coupler, and the connection end of each waveguide of the arrayed waveguide grating is connected to the multi-stage 1x2 Y-waveguide input beam splitting coupling The end of the waveguide.

19. The asymmetric array waveguide grating device according to claim 18,

20. An asymmetric array waveguide grating device, comprising:

An array waveguide grating, which is composed of a plurality of waveguides of different lengths, and is connected to the input beam splitting coupler; A star-shaped focusing coupler connected to the arrayed waveguide grating, which converts the role dispersion of signals of different wavelengths into a spatial displacement dispersion with a focus line;

It is characterized in that it further comprises an optical attenuator or amplifier, which is used in at least a part of the waveguides of the arrayed waveguide grating, which are combined with the coupling coefficients of the input waveguide and the waveguide of the arrayed waveguide grating, so that A defined light intensity distribution function is generated at the interface between the waveguide grating and the focusing star coupler at the output end. This light intensity distribution function is equal to a sine function divided by a Gaussian function, so as to obtain a through light with a steep top and flat sides Pan response curve.

21. The asymmetric array waveguide grating device according to claim 20,

It is characterized in that the sine function is obtained by performing an inverse Fourier transform on a desired spectral response, and the Gaussian function is obtained by performing an inverse Fourier transform on a mode field distribution of a single-channel output waveguide, and the Fourier transform and The optical properties of the focusing star coupler correspond.

22. The asymmetric array waveguide grating device according to claim 21,

It is characterized in that the length of each waveguide of the arrayed waveguide grating needs to be adjusted, in addition to generating a phase difference equal to an integer multiple of 2 π of a given channel wavelength between adjacent waveguides. The phase difference introduced by the input beam splitter coupler, and in some waveguides, produces a π phase shift required when the field distribution function at the connection between the predetermined output coupler and the array waveguide is negative. .

23. An asymmetric arrayed waveguide grating device, comprising:

It is characterized in that the input beam splitting coupler is a multi-stage 1 X 2 Y-type waveguide coupler, and the tail end of each waveguide of the array waveguide grating is connected to the waveguide tail of the coupler.

24. The asymmetric array waveguide grating device according to claim 23,

It is characterized in that at least some of the multi-stage 1 X 2 Y-waveguide couplers have unbalanced coupling coefficients, so that the energy of each waveguide coupled to the arrayed waveguide grating has a predetermined distribution function.