CN102914881A - Polymer waveguide Bragg double-faced grating filter capable of double-electrode temperature tuning - Google Patents

Abstract

The invention discloses a polymer waveguide Bragg double-faced grating filter capable of double-electrode temperature tuning. The grating filter comprises a constant temperature plate, a silicon base plate, a lower cladding layer, a lower electrode, a waveguide double-faced grating, an upper cladding layer and an upper electrode, wherein the constant temperature plate, the silicon base plate, the lower cladding layer, the lower electrode, the waveguide double-faced grating, the upper cladding layer and the upper electrode are sequentially overlapped together from up to down; the lower electrode and the upper electrode are both provided with electrode leads and are connected with a current source to form a temperature raising device through the electrode leads; and the waveguide double-faced grating comprises a lower grating, a straight waveguide and an upper grating and is formed in a manner that the lower grating, the straight waveguide and the upper grating are sequentially overlapped from down to up. According to the polymer waveguide Bragg double-faced grating filter capable of the double-electrode temperature tuning, grating structures are carved at both two sides of the waveguide double-faced grating, so that the difference value of effective refractive indexes of periodic waveguides are amplified along with the grating structures, and the reflectivity is amplified as well; and meanwhile, the tuning velocity is relatively fast, the reflectance spectrum parameters are relatively stable, the very good reflection and tuning effects are realized, the length of the grating can be effectively decreased, and the effect beneficial for device integration is achieved.

Description

Bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter

Technical field

The invention belongs to fiber grating components and parts field, relate in particular to and relate to thermo-optical tunability polymer waveguide Bragg grating design and fabrication technology.

Background technology

The waveguide optical grating wave filter is the Primary Component in the wavelength-division multiplex system.Along with the development of technology, integrated waveguide optical grating has been widely used in waveguide input/output coupler, beam splitter, wave filter, sensor.Organic polymer because have low, thermally-stabilised and high, the high thermo-optical coeffecient of reliability of loss and low-thermal conductivity, compatible good, cheap, be easy to the advantages such as integrated.At present, organic polymer becomes important materials in the integrated optics gradually.Can make designs and be manufactured with larger dirigibility with organic polymer material.The polymeric material thermo-optic effect is apparent in view simultaneously, is fit to preparation polymeric thermo-optic tuned light gate device.

The problems such as conventional temperature tuned light gate device only has single grating and unitary electrode, owing to be subject to the restriction of structure, exists reflectance peak not high, and grating length is long, the thermo-optical tunability scope is little, modulation rate is low have affected the overall performance of device

Summary of the invention

Goal of the invention: for the problem and shortage of above-mentioned existing existence, it is larger to the invention provides interior effective refractive index difference of a kind of cycle, reflectivity is larger, and bipolar electrode carries out the bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter of the control of electric current simultaneously, makes its tuning speed faster.The reflectance spectrum parameter is more stable.

Technical scheme: for achieving the above object, the present invention is by the following technical solutions: a kind of bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter, comprise temperature-constant plate, silicon substrate, under-clad layer, bottom electrode, the two-sided grating of waveguide, top covering and top electrode, described temperature-constant plate, silicon substrate, under-clad layer, bottom electrode, the two-sided grating of waveguide, top covering and top electrode are superimposed together from the bottom up successively; Described bottom electrode and top electrode are equipped with contact conductor, and connect to form heat riser by this contact conductor and current source; The two-sided grating of described waveguide comprises lower grating, straight wave guide and upper grating, and consists of by described lower grating, straight wave guide and upper grating are superimposed successively from bottom to up.

The present invention all is carved with optical grating construction in the two-sided grating of waveguide both sides,, thus the difference of cycle waveguide effective refractive index can be increased thereupon, and reflectivity also can increase.Wave filter when work current source output current makes the two-sided grating of waveguide both sides top electrode and bottom electrode produce simultaneously heat it to be carried out thermal tuning, can make tuning speed faster, and reflection parameters is more stable.

As preferably, the material thermo-optical coeffecient of described under-clad layer, top covering and the two-sided grating of waveguide is negative.Waveguide dual light grid material is chosen as the larger polymeric material of thermo-optical coeffecient, and two electrodes are selected the heating electrode of Current Control up and down.By the variation of Injection Current capable of regulating wave-guide grating structure effective refractive index, then resonance wavelength can change thereupon.Realize the function of wavelength thermal tuning.

As preferably, described waveguide dual light grid material adopts the ultraviolet light polymerization organic polymer, and the hot light characteristic of this organic polymer is-1.8 * 10 ^-4/ ℃

Beneficial effect: compared with prior art, the present invention has the following advantages: all be carved with optical grating construction in the two-sided grating of waveguide both sides, thereby the difference of cycle waveguide effective refractive index can be increased thereupon, reflectivity also can increase; Bipolar electrode carries out the control of electric current simultaneously, can be so that tuning speed to be faster, and the reflectance spectrum parameter is more stable, realizes well reflection, tuning effect, can effectively reduce the length of grating, accomplishes to be beneficial to the integrated effect of device.

Description of drawings

Fig. 1 is structural representation of the present invention;

Fig. 2 is the reflectivity thermal tuning contrast of the embodiment of the invention and conventional waveguide grating filter;

Fig. 3 is the bandwidth thermal tuning contrast of the embodiment of the invention and conventional waveguide grating filter;

Fig. 4 is the wavelength thermal tuning contrast of the embodiment of the invention and conventional waveguide grating filter.

Embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, should understand these embodiment only is used for explanation the present invention and is not used in and limits the scope of the invention, after having read the present invention, those skilled in the art all fall within the application's claims limited range to the modification of the various equivalent form of values of the present invention.

As shown in Figure 1, a kind of bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter is superimposed together temperature-constant plate 1, silicon substrate 2, under-clad layer 3, bottom electrode 4, the two-sided grating of waveguide, top covering 5 and top electrode 6 from the bottom up successively; Extraction electrode lead-in wire 10 on described bottom electrode 4 and top electrode 6, and connect to form the heat riser of heating usefulness by this contact conductor 10 and current source 11, the two-sided grating of simultaneously above-mentioned waveguide comprises lower grating 7, straight wave guide 8 and upper grating 9, and consists of by described lower grating 7, straight wave guide 8 and upper grating 9 are superimposed successively from bottom to up.Under the room temperature, light transmits central wavelength lambda in the two-sided grating of waveguide _B=2n _EffΛ, three dB bandwidth $\mathrm{\Δ\λ}={\mathrm{\λ}}_B\sqrt{{\left(\frac{\mathrm{\Δn}}{{2n}_{\mathrm{eff}}}\right)}^2+{\left(\frac{\mathrm{\Λ}}{L}\right)}^2},$ Reflectivity $R_{\max }={\tanh }^2\left(\mathrm{\πL}\frac{\mathrm{\Δn}}{n_{\mathrm{eff}}}\right)$ Ripple be reflected back n wherein _EffBe the waveguide effective refractive index, Λ is the grating cycle, and Δ n represents the mean change of effective refractive index in the one-period, and L is grating length.

To wavelength expression formula both sides differential: Δ λ _B=2 Δ n _EffΛ+2n _EffΔ Λ (1)

Both sides are than upper λ _B, $\frac{{\mathrm{\Δ\λ}}_B}{{\mathrm{\λ}}_B}=\frac{2{\mathrm{\Δn}}_{\mathrm{eff}}\mathrm{\Λ}}{{2n}_{\mathrm{eff}}\mathrm{\Λ}}+\frac{{2n}_{\mathrm{eff}}\mathrm{\Δ\Λ}}{{2n}_{\mathrm{eff}}\mathrm{\Λ}}---\left(2\right)$

Wherein

Temperature variation, material expands, and makes simultaneously variations in refractive index.

Make K _T=ζ+α, then $\frac{{\mathrm{\Δ\λ}}_B}{{\mathrm{\λ}}_B}=K_T\mathrm{\ΔT}---\left(3\right)$

The two-sided grating of described waveguide adopts the device of negative thermo-optical coeffecient material.During current source 11 work, electric current passes to top electrode 6 by contact conductor 10 and bottom electrode 4 produces heat, and heat transmits to waveguide grating device from electrode, and the waveguide optical grating temperature raises, K _TFor negative, resonance wavelength raises with temperature and reduces.

Because it is near that the two-sided grating medium wave of waveguide is led the high part part ionization electrode low than waveguide, suffered temperature effect is large, and the effective refractive index intensity of variation is large, and Δ n can raise with temperature and reduce to tend towards stability gradually (although n _EffAlso reduce, its reciprocal increasing, but the impact that produces is less than Δ n, so mainly see Δ n impact), then reflectivity and bandwidth can raise with temperature and reduce.Continuously change electric current, just can realize the function of wavelength continuous tuning.Select commercial organic polymer ultra-violet curing ZPU series material, the hot light characteristic K of this material _T=-1.8 * 10 ^-4/ ℃, design parameter is as shown in table 1.

The two-sided grating design parameter of table 1 thermal tuning waveguide

Design parameters	Title	Value of consult volume
			λ 0	Room temperature centre wavelength	1555nm
N cla	Cladding index	1.44
			N cor	The sandwich layer refractive index	1.46
Λ	The grating cycle	0.535μm
			L	Grating length	6mm
Th u	Top covering 5 thickness	3μm
			Th d	Under-clad layer 3 thickness	9μm
High	Duct height	6μm
			Width	Duct width	6μm

High g	The grating height	0.6μm
			Width ele	Electrode width	8μm
Δλ	Wavelength tuning range	10nm

The reflectivity of present embodiment and conventional waveguide grating filter structure, bandwidth, wavelength thermal tuning contrast situation are shown in Fig. 2～4.Present embodiment structure reflectivity is between 43.47-42.60dB in the tuning range, and the traditional structure reflectivity that utilizes the parameter designing such as identical waveguide length, width to go out only is 12.90-21.31dB, and new construction is far above the traditional raster structure; Although slightly higher than traditional structure between the bandwidth 0.554nm-0.542nm of present embodiment, can satisfy wave filter to the requirement of bandwidth characteristic; Present embodiment reflectivity, bandwidth parameter are more stable in tuning range.In 0-60 ℃ of scope of temperature rising, traditional structure wavelength tuning 7.01nm, tuning speed-0.1168nm/ ℃, and present embodiment tuning range 10.4nm, tuning speed-0.1733nm/ ℃, wavelength tuning speed ratio traditional structure is fast, and the tunable wave length scope is larger during the rising uniform temp.

Claims (3)

1. bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter, it is characterized in that: comprise temperature-constant plate (1), silicon substrate (2), under-clad layer (3), bottom electrode (4), the two-sided grating of waveguide, top covering (5) and top electrode (6), described temperature-constant plate (1), silicon substrate (2), under-clad layer (3), bottom electrode (4), the two-sided grating of waveguide, top covering (5) and top electrode (6) are superimposed together from the bottom up successively; Described bottom electrode (4) and top electrode (6) are equipped with contact conductor (10), and connect to form heat riser by this contact conductor (10) and current source (11); The two-sided grating of described waveguide comprises lower grating (7), straight wave guide (8) and upper grating (9), and by described lower grating (7), straight wave guide (8) and upper grating (9) superimposed formation successively from bottom to up.

2. described bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter according to claim 1, it is characterized in that: the material thermo-optical coeffecient of described under-clad layer, top covering (5) and the two-sided grating of waveguide is negative.

3. described bipolar electrode thermal tuning polymer waveguide Bragg dual light grating filter according to claim 1, it is characterized in that: described waveguide dual light grid material adopts the ultraviolet light polymerization organic polymer, and the hot light characteristic of this organic polymer is-1.8 * 10 ^-4/ ℃.

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