CN102789023A - Photonic crystal beam splitter - Google Patents
Photonic crystal beam splitter Download PDFInfo
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- CN102789023A CN102789023A CN2011101281812A CN201110128181A CN102789023A CN 102789023 A CN102789023 A CN 102789023A CN 2011101281812 A CN2011101281812 A CN 2011101281812A CN 201110128181 A CN201110128181 A CN 201110128181A CN 102789023 A CN102789023 A CN 102789023A
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Abstract
The invention relates to a photonic crystal beam splitter which realizes the beam splitting and propagating of the inputted optical signals by the auto-collimation effect of the SOI (silicon on insulator) based two-dimensional flat air-hole photonic crystal, belonging to the field of optical technology of the semiconductors. The photonic crystal beam splitter comprises an SOI substrate, an air hole area and an SOI stripe-shaped waveguide; the air hole area is formed on the top-layer silicon of the SOI substrate by etching silicon; the SOI stripe-shaped waveguide is used for connecting the air hole area with the external optical fiber or other devices; the air holes formed by etching silicon in the air hole area are arrayed on the top-layer silicon of the SOI substrate like square crystal lattices; the depth of the air holes is equal to the thickness of the top-layer silicon of the SOI substrate; and the SOI stripe-shaped waveguide is the inputting waveguide of the beam-splitter and keeps a certain distance with both the air hole area and two borders which are parallel to the inputting waveguide. The length of the beam splitting area of the beam splitter can be controlled with 10mum, thus the overall length of the device is reduced greatly, and the structure is more compact. In addition, the photonic crystal beam splitter has large preparation tolerance and more flexible design and can be more widely used for the future photonic chip.
Description
Technical field
The present invention relates to a kind of photonic crystals splitter that is applied to fields such as optical communication, photometry calculation, light sensing and optical measurement, particularly a kind of photonic crystals splitter structure with the SOI material belongs to the semiconductor optical technical field.
Background technology
In half a century, the microelectric technique of taking as the leading factor with silicon has obtained remarkable achievement in the past, big force urges the arrival infotech golden age.Silicon aspect market monopoly position and in the huge advantage of process aspect, attracting people constantly to research and develop miniaturization, integrated silicon based photon device, to realize extensive integrated photon chip.
(Silicon-on-Insulator is a kind of silica-base material system of uniqueness SOI) to silicon on the insulator, adopts this material optoelectronic device to help compatible mature C MOS technology, realizes that large-scale photon is integrated integrated with photoelectricity.But common SOI optical waveguide size is bigger, and corresponding devices is difficult to realize highdensity integrated chip, so the notion of photonic crystal is arisen at the historic moment.
So-called photonic crystal refers to the periodically-varied of refractive index generation wavelength dimension, has the material structure of certain photon band gap (PBG).The appearance of photonic crystal is for photoelectricity and photon integrated chip in the future opened up a new road.Such as, photon crystal wave-guide is leaded light through the restriction effect of band gap, because duct width in wavelength magnitude, just can make the size of waveguide device greatly reduce.
The 3-D photonic crystal that produces complete photonic band gap also has certain difficulty on making, therefore, the 2 D photon crystal flat board is the optimal selection of constructing photon crystal device at present.In plate level, produce the light restriction through forbidden photon band, and on direction, produce the light restriction through index guide structure perpendicular to planar waveguide.If periodic airport is distributed in the dielectric material, will produce bigger photon band gap to the TE mould, if periodic medium post is distributed in the air, will produce bigger photon band gap to the TM mould.
Y type luminous power beam splitter is the basic device in optics and the photoelectric field.But present waveguide type Y beam splitter reaches several thousand microns mostly, and the Y beam splitter of optical-fiber type reaches several millimeters especially, and this large-sized device can't be applied in the in the future large-scale integrated photon chip.
The device miniaturization that appears as of photonic crystal provides a new way.Yet the photonic crystal Y beam splitter of ordinary construction is generally introduced defective aperture (or defective post) at the cross-connecting area of input, output waveguide and is improved beam splitting efficient, reduces to insert loss.Fig. 1 is the structural representation of traditional photonic crystal Y beam splitter.As shown in Figure 1, this structure need be introduced the less silicon post (being the defective post) of diameter in the junction of input waveguide and output waveguide, and to reduce device loss, to improve output efficiency, this just needs more accurate exposure technology.The maximum deficiency of this structure is that the making tolerance is little, and the diameter of defective hole or defective post often has only tens nanometers, and its position also needs accurately to confirm, thereby brings very big difficulty to actual fabrication.
Summary of the invention
The technical matters that the present invention will solve provides a kind of photonic crystals splitter, is used to overcome the more accurate exposure technology of existing photonic crystal Y beam splitter needs, makes problems such as tolerance is little.
For solving the problems of the technologies described above; The present invention adopts following technical scheme: a kind of photonic crystals splitter (200) is characterized in that: this photonic crystals splitter comprises SOI substrate (100), is airport zone (220) that tetragonal arranges and the SOI slab waveguide (210) that this airport zone (220) is connected with external devices what the top layer silicon (103) of SOI substrate went up that etching forms; Said SOI substrate (100) comprises substrate silicon layer (101), is positioned at the silicon dioxide buried regions (102) on the substrate silicon layer (101) and is positioned at the top layer silicon (103) on this silicon dioxide buried regions (102); The degree of depth (h) of the airport (221) in said airport zone equals the thickness (d) of SOI top layer silicon (103).
Further, the height H of said SOI bar shaped input waveguide equates with the degree of depth h of airport.
Further, the relation of the grating constant a of the thickness d of said top layer silicon (103) and said airport does
0.5a≤h≤0.6a, the thickness of said silicon dioxide buried regions (102) is at least 2.64a.
Further, the relation of the radius r of said airport and grating constant a is r >=0.2a.
Further, the relation of the radius r of said airport and grating constant a is 0.3a≤r≤0.4a.
Further, it is 230nm that said top layer silicon (103) gets thickness, and said silicon dioxide buried regions thickness is 1 μ m, and the grating constant that said airport tetragonal is arranged is 380nm, and said airport radius is 140nm.
Further, the width K of said SOI bar shaped input waveguide be at least the grating constant a of said airport
doubly.
Further, said airport adopts electron beam exposure, inductively coupled plasma technology etching or FIB etching to form.
The present invention also comprises a kind of preparation method of photonic crystals splitter, and it may further comprise the steps:
1) preparation SOI substrate;
2) top layer silicon (103) at above-mentioned SOI substrate goes up the airport zone (220) that is the tetragonal arrangement of etching formation and the SOI slab waveguide (210) that this airport zone (220) is connected with external devices; The degree of depth h of the airport (221) in said airport zone is for equaling the thickness d of SOI top layer silicon (103), and said SOI slab waveguide edge is respectively L1, L2 to the distance on (220) border, said airport zone, and wherein L1, L2 are greater than 0.
Further, the height (H) of said SOI bar shaped input waveguide equates with the degree of depth (h) of airport.
Technique effect of the present invention is; This photonic crystal beam splitter is compared with traditional Y beam splitter, owing to adopt photon crystal structure to realize the beam splitting of light beam fully, the length in beam splitting district can be controlled in the 10 μ m; This greatly shortens the length of total device, and structure is more compact; Simultaneously, compare with common photonic crystal Y beam splitter, it need not introduce defective post or defective hole, and the preparation tolerance is bigger, design is more flexible, can be used in more widely in following photon chip.In addition, photonic crystals splitter structure provided by the invention is based on the SOI substrate, and with present mature C MOS process compatible, preparation technology is simple ripe, with low cost.
Description of drawings
Fig. 1 is the structural representation of common SOI photonic crystal Y beam splitter;
Fig. 2 can be with isofrequency map for two-dimension square lattice airport slab photonic crystal TE pattern first;
Fig. 3 is the structural representation of SOI photonic crystals splitter provided by the invention;
Fig. 4 is the used SOI material side view of the present invention;
Fig. 5 is a SOI photonic crystals splitter side view provided by the invention;
Fig. 6 is a SOI photonic crystals splitter FDTD simulation result synoptic diagram provided by the invention;
The component symbol mark
Embodiment
For making the object of the invention, technical scheme and advantage clearer, the present invention is made further detailed description below in conjunction with accompanying drawing.
In general, through photonic crystal inner introduce defective as passage can lead beam transmission.But photonic crystal also has the character of a uniqueness---auto-collimation effect.Based on this effect, need not introduce any defective in photonic crystal inside, light beam self just can overcome diffraction and disperse collimation and transmit forward.This characteristic comes from the dispersion relation of photonic crystal, and the autocollimation light beam also have the zero crossing effect except can autocollimation the transmission, and the insensitive effect of angle is to effects such as the photon crystal structure precision are insensitive.
Fig. 2 can be with isofrequency map for two-dimension square lattice airport slab photonic crystal TE pattern first.
In the airport photon crystal structure that tetragonal is arranged; Utilize plane wave expansion method can obtain the equifrequency line chart of photon crystal structure; As shown in Figure 2, under electric field polarization (TE) situation, in the equifrequency line that the airport photonic crystal first that tetragonal is arranged can be with; Representing frequency is that the equifrequent line of 0.228c/a (wherein: c is the light velocity, and a is the tetragonal grating constant) is at k
y(2 π/a) are (very smooth in the scope of 2 π/a), and its normal direction k between turned letter to 0.05 to be in-0.05
xDirection, (11) direction of lattice, i.e. tetragonal diagonal in the corresponding real space.
Because the energy direction of propagation of electromagnetic field is exactly the group velocity direction; We know according to this relational expression to satisfy relational expression
; The direction of propagation that can flow is perpendicular to the direction of equifrequent line, and promptly light beam will be propagated along the normal direction of equifrequent line.Therefore, can know by inference, be the light beam of 0.228c/a for frequency, at k
y((communication mode of all wave vector representatives in the scope of 2 π/a) all will be along k to 0.05 for 2 π/a) to be in-0.05
xDirection is propagated and is not dispersed.This in photonic crystal of light beam receives structure chromatic dispersion relation constraint and phenomenon that collimation is propagated is exactly an auto-collimation effect.In addition; For said structure; Near frequency is 0.228c/a equifrequent line is all relatively smooth, therefore first can with in be the autocollimation phenomenon that tangible light beam is propagated along two-dimension square lattice airport slab photonic crystal tetragonal diagonal all can occur in the band frequency scope at center with frequency 0.228c/a.
Fig. 3 is a photonic crystals splitter structural representation provided by the invention.
The photonic crystals splitter 200 that this embodiment provides is based on the SOI substrat structure; SOI backing material side view is as shown in Figure 4; The SOI backing material 100 that this embodiment adopted comprises: substrate silicon layer 101, silicon dioxide buried regions 102 and top silicon layer 103.
As shown in Figure 3; The photonic crystals splitter 200 based on SOI substrate 100 that this embodiment provides comprises: in the airport zone 220 that SOI substrate top layer silicon 103 etchings form, and the SOI slab waveguide 210 that airport zone 220 is linked to each other with external fiber or other devices.Wherein, In the airport zone 220; The airport 221 that etching forms is tetragonal and is arranged on the SOI top layer silicon 103; Its degree of depth is the thickness of SOI top layer silicon 103; SOI slab waveguide 210 is the input waveguide of photonic crystals splitter 200, and its two border A, B apart from airport regional 220 has distance L 1, L2 respectively, and above-mentioned two distances can equate; Also can be unequal, but L1, L2 are all greater than
of propagation distance after the light beam beam splitting in the beam splitter doubly.
In this embodiment; The height H of SOI slab waveguide 210 equates with the degree of depth h of airport 221; Be the thickness d of SOI top layer silicon 103; The relation of the grating constant of this degree of depth h and airport 221 is: 0.5 * grating constant≤top layer silicon thickness≤0.6 * grating constant, and the thickness of SOI substrate silicon dioxide buried regions 102 is at least 2.64 * grating constant; The radius r of airport 221 and the relation of grating constant are: r airport radius>=0.2 * grating constant, optional, the radius of airport and the relation of grating constant are: 0.36 * grating constant≤airport radius≤0.38 * grating constant.
As preferred forms, SOI top layer silicon 103 thickness are 230nm, and silicon dioxide buried regions 102 thickness are 1 μ m, and the grating constant that airport 221 tetragonals are arranged is 380nm, and the radius of airport 221 is 140nm.At this moment, near frequency is 0.235c/a, be communication band, have auto-collimation effect along middle lattice diagonal (tetragonal diagonal line defence line in the corresponding real space) between turned letter.In addition, airport 221 radiuses are between 0.36 * grating constant～0.38 * grating constant, and between 0.5 * grating constant～0.6 * grating constant, the autocollimation frequency is all near 0.235c/a for top layer silicon thickness (being airport 221 degree of depth).
In the photonic crystals splitter 200 that this embodiment provides,
that the width k of SOI slab waveguide 210 is at least airport 221 grating constants (that is: 221 crystalline network cycles of airport) doubly.
The airport 221 photon crystal structure side views that relate in this embodiment are as shown in Figure 5, and airport 221 structures that are arranged in SOI top layer silicon 103 form through electron beam exposure, inductively coupled plasma technology etching or FIB or standard CMOS process etching.
The photonic crystals splitter structure FDTD simulation result synoptic diagram that Fig. 6 provides for this embodiment.As shown in Figure 6; SOI slab waveguide 210 is along the length of side direction input of airport 221 tetragonals; Because the auto-collimation effect of two-dimension square lattice airport slab photonic crystal; After light transmission gets into photonic crystal region 220, promptly propagate, thereby realize 90 ° of beam splitting along photonic crystal tetragonal diagonal.
Simultaneously, owing to being the light beam of 0.228c/a, at k to frequency
y((communication mode of all wave vector representatives in the scope of 2 π/a) all will be along k to 0.05 for 2 π/a) to be in-0.05
xDirection is propagated and is not dispersed; When the length of side of the input direction of SOI slab waveguide 210 and airport 221 tetragonals at an angle the time; Still propagate along two tetragonal diagonals the direction of propagation of light in photonic crystal region 220; That is: the small angle variation of input waveguide, the photonic crystals splitter beam splitting effect did not influence that this embodiment is provided.
In addition; Opposite side in photonic crystal region 220; Output waveguide can be set; To draw along the light beam that the beam splitting of photonic crystal lattice diagonal is propagated,
that the width of output waveguide is at least airport 221 grating constants (that is: 221 crystalline network cycles of airport) equally doubly.
The photonic crystals splitter structure that this embodiment provides; Utilize the beam splitting of the auto-collimation effect realization input optical signal of SOI base two-dimensional flat plate airport photonic crystal to propagate; Compare with traditional Y beam splitter, owing to adopt photon crystal structure to realize the beam splitting of light beam fully, the length in beam splitting district can be controlled in the 10 μ m; This greatly shortens the length of total device, and structure is more compact; Simultaneously, compare with common photonic crystal Y beam splitter, it need not introduce defective post or defective hole, and the preparation tolerance is bigger, design is more flexible, can be used in more widely in following photon chip.In addition, photonic crystals splitter structure provided by the invention is based on the SOI substrate, and with present mature C MOS process compatible, preparation technology is simple ripe, with low cost.
It is understandable that though the present invention with the preferred embodiment disclosure as above, yet the foregoing description is not in order to limit the present invention.For any those of ordinary skill in the art; Do not breaking away under the technical scheme scope situation of the present invention; All the technology contents of above-mentioned announcement capable of using is made many possible changes and modification to technical scheme of the present invention, or is revised as the equivalent embodiment of equivalent variations.Therefore, every content that does not break away from technical scheme of the present invention, all still belongs in the scope of technical scheme protection of the present invention any simple modification, equivalent variations and modification that above embodiment did according to technical spirit of the present invention.
Claims (10)
1. a photonic crystals splitter (200) is characterized in that: this photonic crystals splitter comprises SOI substrate (100), is airport zone (220) that tetragonal arranges and the SOI slab waveguide (210) that this airport zone (220) is connected with external devices what the top layer silicon (103) of SOI substrate went up that etching forms; Said SOI substrate (100) comprises substrate silicon layer (101), is positioned at the silicon dioxide buried regions (102) on the substrate silicon layer (101) and is positioned at the top layer silicon (103) on this silicon dioxide buried regions (102); The degree of depth (h) of the airport (221) in said airport zone equals the thickness (d) of SOI top layer silicon (103).
2. photonic crystals splitter according to claim 1 is characterized in that, the height H of said SOI bar shaped input waveguide equates with the degree of depth h of airport.
3. photonic crystals splitter according to claim 1 is characterized in that, the relation of the thickness d of said top layer silicon (103) and the grating constant a of said airport is 0.5a≤h≤0.6a, and the thickness of said silicon dioxide buried regions (102) is at least 2.64a.
4. photonic crystals splitter according to claim 1 is characterized in that, the relation of the radius r of said airport and grating constant a is r >=0.2a.
5. photonic crystals splitter according to claim 4 is characterized in that, the relation of the radius r of said airport and grating constant a is 0.3a≤r≤0.4a.
6. according to claim 3 or 4 or 5 described photonic crystals splitters; It is characterized in that it is 230nm that said top layer silicon (103) gets thickness, said silicon dioxide buried regions thickness is 1 μ m; The grating constant that said airport tetragonal is arranged is 380nm, and said airport radius is 140nm.
7. photonic crystals splitter according to claim 1; It is characterized in that, the width K of said SOI bar shaped input waveguide be at least said airport grating constant a
doubly.
8. photonic crystals splitter according to claim 1 is characterized in that, said airport adopts electron beam exposure, inductively coupled plasma technology etching or FIB etching to form.
9. the preparation method of a photonic crystals splitter (200) is characterized in that, may further comprise the steps:
1) preparation SOI substrate;
2) top layer silicon (103) at above-mentioned SOI substrate goes up the airport zone (220) that is the tetragonal arrangement of etching formation and the SOI slab waveguide (210) that this airport zone (220) is connected with external devices; The degree of depth h of the airport (221) in said airport zone is for equaling the thickness d of SOI top layer silicon (103), and said SOI slab waveguide edge is respectively L1, L2 to the distance on (220) border, said airport zone, and wherein L1, L2 are greater than 0.
10. the preparation method of photonic crystals splitter according to claim 9 (200) is characterized in that, the height of said SOI slab waveguide (H) equates with the degree of depth (h) of airport.
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| CN2011101281812A CN102789023A (en) | 2011-05-18 | 2011-05-18 | Photonic crystal beam splitter |
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| CN2011101281812A CN102789023A (en) | 2011-05-18 | 2011-05-18 | Photonic crystal beam splitter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110673335A (en) * | 2019-09-01 | 2020-01-10 | 复旦大学 | Photonic crystal light splitting device and design method thereof |
| CN115343803A (en) * | 2022-08-23 | 2022-11-15 | 中国地质大学（武汉） | Annular wavelength demultiplexer arranged on silicon substrate and design method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1967298A (en) * | 2005-11-18 | 2007-05-23 | 中国科学院半导体研究所 | Photonic crystals splitter based on SOI and preparing method |
| CN101162279A (en) * | 2006-10-13 | 2008-04-16 | 中国科学院半导体研究所 | Single-mode photon crystal polarization beam splitter |
-
2011
- 2011-05-18 CN CN2011101281812A patent/CN102789023A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1967298A (en) * | 2005-11-18 | 2007-05-23 | 中国科学院半导体研究所 | Photonic crystals splitter based on SOI and preparing method |
| CN101162279A (en) * | 2006-10-13 | 2008-04-16 | 中国科学院半导体研究所 | Single-mode photon crystal polarization beam splitter |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110673335A (en) * | 2019-09-01 | 2020-01-10 | 复旦大学 | Photonic crystal light splitting device and design method thereof |
| CN115343803A (en) * | 2022-08-23 | 2022-11-15 | 中国地质大学（武汉） | Annular wavelength demultiplexer arranged on silicon substrate and design method thereof |
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Application publication date: 20121121 |