CN107765375B - Chip based on double-layer grating-fiber perpendicular coupled structure - Google Patents
Chip based on double-layer grating-fiber perpendicular coupled structure Download PDFInfo
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- CN107765375B CN107765375B CN201711166105.4A CN201711166105A CN107765375B CN 107765375 B CN107765375 B CN 107765375B CN 201711166105 A CN201711166105 A CN 201711166105A CN 107765375 B CN107765375 B CN 107765375B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
Abstract
The chip based on double-layer grating-fiber perpendicular coupled structure that the invention discloses a kind of.The coupled structure includes substrate, transmission medium layer, lower layer's grating, extension dielectric layer and upper layer grating, wherein upper layer grating and lower layer's grating make 0 grade of diffracted intensity of incident light minimum, and 90 degree of deviation occurs for incident light direction of propagation after coupled structure.The present invention realizes optical fiber-chip chamber vertical incidence efficient coupling using double-layer grating structure, and such design structure compares existing coupling grating structure, has the advantages that complete vertical incidence, structure are simple, easy to process, efficiency is higher.Using structure of the invention, between communication band (1300-1700nm) optical fiber-SOI waveguide 48% coupling efficiency may be implemented.
Description
Technical field
Chip-fiber perpendicular coupling double-layer grating structure is realized the present invention relates to a kind of.
Background technique
The development trend of chip is the photoelectricity hybrid integrated of electrical-optical-electrical, micro-optoelectronic integrated chip be by integrated circuit with
Photonic integrated device is simultaneously integrated, and realizing has the optoelectronic intagration system of real value.In light network, light exchange, optical signal
Processing etc. has great importance and broad application prospect.With the development of silicon based opto-electronics electronic technology, silicon compared with
It is smaller and smaller that big refractive index makees device, can be integrated on the same chip by more optoelectronic function devices.
Since current silicon substrate light source is difficult to realize, general light source selects external laser.Therefore need a coupler will
The light source couples of external laser enter in chip of light waveguide.Traditional the simplest method is that optical fiber is straight with nano optical wave guide
Docking is connect, but due to about more than ten microns of the size of optical fiber, and waveguide is only several hundred nanometers, there is serious between the two
Mode mismatch problem causes coupling loss very big, and coupling efficiency is relatively low, therefore vertical coupled using the grating of grating coupler
Method has obtained more and more concerns.Grating coupled advantage is that grating coupler is that waveguide table is realized using the diffraction of light
Face optical coupling, can be with effective solution optical fiber and the unmatched problem of waveguide mode, and coupling efficiency is high and is easily integrated.
Using grating coupled principle changed using the refractive index cycle of grating, its incident light and diffraction light is made to meet cloth
Glug condition, to realize efficient coupling.In order to improve the efficiency of coupling, the secondary Prague for needing to minimize grating is anti-
Penetrate, backwards to and downward intensity in transmission.2003, Hisao KIKUTA delivered entitled " Optical Elements with
Subwavelength Structured Surfaces " article (OPTICAL REVIEW Vol.10, No.2 (2003) 63-
73) relationship of structure (the mainly duty ratio) and grating effective refractive index of grating, is analyzed using EFFECTIVE MEDIUM THEORY, it is indicated that
The duty ratio for adjusting grating can be such that the effective refractive index of grating changes within the scope of one.Some studies pointed out that grating knots quickly
Structure can not only have the periodic modulation of refractive index in one direction, can also there is periodic modulation in two directions
(SWGS)[Daniel Benedikovic,Pavel Cheben,“Subwavelength index engineered
surface grating coupler with sub-decibel efficiency for 220-nm silicon-on-
insulator waveguide,"Opt.Express 23,22628-22635(2015)].This optical grating construction is due to being single layer
And be that light engraving loses, so have the characteristics that it is easy to process, but it in order to reduce secondary Bragg reflection needs make into
Penetrating optical fiber has a small inclination angle, so being industrially unfavorable for package application.
Another scheme be using chirp grating and perfect Bragg reflection grating structure [A.M.J.Koonen,
Haoshuo Chen,Henrie P.A.van den Boom,Oded Raz,“Silicon Photonic Integrated
Mode Multiplexer and Demultiplexer,”,Photonics Technology Letters IEEE,
Vol.24, pp.1961-1964,2012, ISSN 1041-1135.], chirp grating can effectively improve to be produced because light field center changes
The variation of raw diffraction maximum, while perfect Bragg grating can make to reflect back as far as possible backwards to wave, to improve coupling effect
Rate.But the coupling efficiency of this grating is relatively low, will cause very big waste.In order to reduce grating under conditions of vertical coupled
Secondary Bragg reflection, occur tool there are two types of the period optical grating construction [Ming Dai, Leilei Ma, Minghui Lu
and Xiaoping Liu,“Highly efficient and perfectly vertical chip-to-fiber dual-
Layer grating coupler, " Opt.Express 23,1691-1698 (2015)], this grating rationally designs structure
Thickness, so that destructive interference occurs just for two layers of reflected light to generate smaller secondary Bragg reflection, then by rationally setting
The structure of photometric grid can make it have directionality.The grating of this structure uses the structure of two kinds of periods dislocation, has higher
Coupling efficiency, but the structure of this dislocation has very big difficulty on micro fabrication.
It can be seen from the above, the efficient vertical raster of wide bandwidth has very big application, market pair in integreted phontonics industry
This grating has very big demand, and mature CMOS integrated technique provides condition for the processing of grating.It designs at present
Vertical coupled optical grating construction much needs a small inclination angle incident, is not vertical incidence truly, some efficiency is inclined
Low, some efficiency is very high difficult to be produced under existing CMOS integrated technique.
Summary of the invention
It for the coupled structure of researching and designing before, or is that non-fully the vertical incidence of meaning or coupling efficiency are inclined
Low or processing technology complexity technical problem needs a kind of efficient, structure to realize core
Piece and extraneous communication.For this purpose, solving the present invention provides a kind of perpendicular coupling structure based on double-layer grating in chip-
The problem of efficient coupling of light is realized between optical fiber.
The purpose of the present invention is realized through the following technical scheme:
Chip based on double-layer grating-fiber perpendicular coupled structure, which is characterized in that the coupled structure includes substrate, passes
Defeated dielectric layer, lower layer's grating, extension dielectric layer and upper layer grating, wherein upper layer grating and lower layer's grating make 0 grade of incident light
Diffracted intensity is minimum, and 90 degree of deviation occurs for incident light direction of propagation after the coupled structure.
Further, the center position of lower layer's grating is equipped with Bragg mirror.
Further, catoptric arrangement is equipped between the substrate and transmission medium layer.
The present invention realizes optical fiber-chip chamber vertical incidence efficient coupling using double-layer grating structure, compares existing
Coupling grating structure has the advantages that complete vertical incidence, structure are simple, easy to process, efficiency is higher:
(1) structure of the invention can be very good to make completely using existing mature CMOS technology, so that coupler
Preparation process greatly simplifies；
(2) fiber port docks completely with optical grating construction, is very beneficial for encapsulation design, easy to use；
(3) coupling efficiency of coupled structure of the present invention is also higher, may be implemented in communication band (1300-1700nm) light
48% coupling efficiency between fibre-SOI waveguide.
Detailed description of the invention
Fig. 1 is the coupled structure schematic diagram the present invention is based on double-layer grating.
Fig. 2 be the present invention using temporal-difference algorithm (3dFDTD) simulation calculate transverse electromagnetic mode (TM0) from fiber coupling to
Coupling efficiency in waveguide.
Fig. 3 is that the present invention is incident from optical fiber using temporal-difference algorithm (3dFDTD) simulation calculating transverse electromagnetic mode (TM0)
Mode conservation degree, i.e., incident mode is propagated in the structure does not change the mode as far as possible.
Specific embodiment
Coupled structure of the invention is situated between as shown in Figure 1, sequentially consisting of substrate, transmission medium, lower layer's grating, extension
Matter, upper layer grating.Diffraction occurs when incident light beam strikes are to upper layer grating, the energy of light beam is concentrated mainly on+1, -1 grade of diffraction light
In, deviation occurs for the direction of propagation of light, on the light beam Random Incident to lower layer's grating after diffraction, so that light spreads out again
It penetrates, so that 90 degree of change occurs for the direction of propagation of final light.Because of double-layer grating gradually diffraction, light is in optical fiber-chip chamber
Coupling efficiency is improved than before using the structure of customization monochromatic light grid.
Different wavelength, different modes incident light under, the structural parameters of grating are it can be selected that make incident light
Coupling efficiency highest.The determination of grating parameter, according to making, the intensity of 0 grade of diffraction is minimum to be determined in principle.Specific structure ginseng
Number can be calculated using first beginning optimization algorithm.
Double-layer grating structure of the invention can be further improved coupling efficiency, such as the center position in lower layer's grating
Design Bragg mirror, or design catoptric arrangement between substrate and transmission medium, with reduce incident light downwards and to
Transmission in rear direction.
The optical path of coupled structure of the present invention has invertibity, not only can be used for light being coupled to chip from fiber perpendicular, but also
It can be used for for light being coupled in optical fiber from Chip Vertical.
The present embodiment coupled structure the preparation method comprises the following steps: first lose one layer of optical grating construction as lower layer's grating on piece light engraving,
Its raster size is matched with fiber cross-sections size；One layer of medium of epitaxial growth on grating again, on it another light of deep etching
Grid structure is matched as upper layer grating, raster size with fiber cross-sections size.The thickness of specific grating structural parameter and medium
Degree is so that coupling efficiency highest optimizes to obtain.Above structure makes light enter on piece from fiber coupling, then passes through adiabatic waveguide connector
It is coupled into light is loss-free in very small size of chip.
To be coupled as example in communication band (1300-1700nm) soi chip and 12um optical fiber, optimization is calculated
Grating parameter be: light engraving loses lower layer's optical grating construction on silicon layer, and screen periods are 0.5-0.7um, etching depth 80-
120nm, grating duty ratio are 0.4-0.6 or so.Etch the upper layer optical grating construction on extension silicon dioxide layer surface, grating week
Phase is 1.2um or so, and etching depth is 0.8um-1.2um (deep etching), and grating duty ratio is 0.7-0.8.The two of extension generation
The thickness of silicon oxide layer is 3um or so.Transmission medium selects silicon.Under such structure, it can see in dispersion map according to fig. 2,
The present invention reaches as high as 48% in communication band transfer efficiency with higher, the coupling efficiency of basic mode.Importantly, this hair
Bright also to have biggish bandwidth, by taking -3dB as an example, bandwidth of the invention is about 65nm.Meanwhile as seen from Figure 3, basic mode exists
When propagating in coupled structure of the invention, hardly change its mode, this is that the present invention has wanting substantially for practical value
It asks.Therefore, chip and extraneous communication can be well realized in coupled structure of the invention.
Claims (3)
1. the chip based on double-layer grating-fiber perpendicular coupled structure, which is characterized in that the coupled structure includes substrate, transmission
Dielectric layer, lower layer's grating, extension dielectric layer and upper layer grating, wherein upper layer grating and lower layer's grating make 0 grade of incident light to spread out
Penetrate that intensity is minimum, diffraction optical propagation direction of the incident light after the coupled structure and incident light direction form 90 degree inclined
Folding；The screen periods of the upper layer grating are 1.2um, and grating depth is 0.8um-1.2um, and grating duty ratio is 0.7-0.8；Institute
The screen periods for stating lower layer's grating are 0.5-0.7um, and grating depth 80-120nm, grating duty ratio is 0.4-0.6；Extension is situated between
The thickness of matter layer is 3um.
2. the chip based on double-layer grating-fiber perpendicular coupled structure according to claim 1, which is characterized in that described
The center position of lower layer's grating is equipped with Bragg mirror.
3. the chip based on double-layer grating-fiber perpendicular coupled structure according to claim 1, which is characterized in that described
Catoptric arrangement is equipped between substrate and transmission medium layer.
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| CN112230339A (en) * | 2020-10-23 | 2021-01-15 | 联合微电子中心有限责任公司 | Grating coupler and preparation method thereof |
| CN117222926A (en) * | 2021-02-24 | 2023-12-12 | 香港中文大学 | Blazed waveguide grating coupler with high coupling efficiency |
| CN114236686A (en) * | 2021-12-21 | 2022-03-25 | 南京邮电大学 | Multi-layer multi-dimensional photon integrated chip light/light inlet/outlet structure and preparation method thereof |
| CN115128733B (en) * | 2022-06-24 | 2023-12-08 | 吉林大学 | Double-grating structure, manufacturing method, optical phased array and laser radar |
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| US9239507B2 (en) * | 2013-10-25 | 2016-01-19 | Forelux Inc. | Grating based optical coupler |
| WO2016201387A1 (en) * | 2015-06-12 | 2016-12-15 | Pacific Biosciences Of California, Inc. | Integrated target waveguide devices and systems for optical coupling |
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