CN217156978U - Thermo-optical modulation planar waveguide Bragg grating and micro OCM or TOF and tunable laser containing same - Google Patents
Thermo-optical modulation planar waveguide Bragg grating and micro OCM or TOF and tunable laser containing same Download PDFInfo
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Abstract
The utility model relates to a thermo-optic modulation planar waveguide type Bragg grating and a micro OCM or TOF containing the structure and a tunable laser, wherein the thermo-optic modulation planar waveguide type Bragg grating comprises a planar waveguide body and a waveguide heating device; the planar waveguide body comprises an optical substrate and a waveguide layer, wherein the waveguide layer comprises a first waveguide film layer, a second waveguide film layer and a third waveguide film layer which are sequentially laminated and plated on the optical substrate, and the refractive index of the second waveguide film layer is respectively greater than that of the first waveguide film layer and that of the third waveguide film layer; the first waveguide film layer, the second waveguide film layer and the third waveguide film layer are all formed by any one of a-Si, a-SiH, a-SiGeH and a-GeH waveguide material, and the second waveguide film layer is used for photoetching Bragg gratings; the waveguide heating device heats the waveguide layer, and the technical scheme is adopted to generate narrow-band reflection wavelength in a larger wavelength range by instantaneous millisecond pulse heating.
Description
Technical Field
The utility model relates to an optical communication technical field, concretely relates to thermo-optic modulation plane waveguide type Bragg grating and contain miniature OCM or TOF and tunable laser of this structure.
Background
The Bragg grating has the characteristics of small volume, good wavelength selectivity, no influence of nonlinear effect, insensitive polarization, easy connection with an optical fiber system, convenient use and maintenance, large bandwidth range, small additional loss, miniaturized device, good coupling property, capability of being integrated with other optical fiber devices and the like, the refractive index change quantity in the optical fiber is related to a plurality of parameters, mainly has the doping level of an irradiation wave optical fiber and the like, the existing Bragg grating directly irradiates the optical fiber with ultraviolet light, and the refractive index is only increased by (10) -4 ) The order of magnitude is already saturated.
SUMMERY OF THE UTILITY MODEL
The utility model provides a not enough to prior art, the utility model provides a narrow band reflection wavelength's in great wavelength range thermophoto modulation planar waveguide type Bragg grating.
The utility model discloses a thermo-optic modulation planar waveguide type Bragg grating adopts following technical scheme: the planar waveguide heating device comprises a planar waveguide body and a waveguide heating device; the planar waveguide body comprises an optical substrate and a waveguide layer, wherein the waveguide layer comprises a first waveguide film layer, a second waveguide film layer and a third waveguide film layer which are sequentially laminated and plated on the optical substrate, and the refractive index of the second waveguide film layer is respectively greater than that of the first waveguide film layer and that of the third waveguide film layer; the first waveguide film layer, the second waveguide film layer and the third waveguide film layer are all formed by any one of a-Si, a-SiH, a-SiGeH and a-GeH waveguide material, and the second waveguide film layer is used for photoetching Bragg gratings; the waveguide heating device heats the waveguide layer.
Further, the Bragg grating is formed by ultraviolet or femtosecond laser photoetching.
Further, the second waveguide film layer is of a single-mode structure.
Further, the first waveguide film layer, the second waveguide film layer and the third waveguide film layer are plated and formed at different evaporation rates or at different temperatures of the optical substrate.
Further, the waveguide heating device is an electromagnetic heating layer or a heating resistance sheet arranged at the bottom of the optical substrate for heating the waveguide layer; or the waveguide heating device is used for irradiating the waveguide layer by arranging the visible light LED core bar above the waveguide layer, and the waveguide layer absorbs light for heating.
The micro OCM or TOF applies any one of the thermo-optically modulated planar waveguide type Bragg gratings, and comprises a photoelectric detector, a circulator, a collimating mirror, a cylindrical lens and a thermo-optically modulated planar waveguide type Bragg grating; the light source emitting light signal is emitted from the end A of the circulator and then from the end B of the circulator, and then is emitted into the second waveguide film layer of the thermo-optic modulation planar waveguide Bragg grating through the collimating mirror and the cylindrical lens in sequence, one part of light is emitted after passing through the Bragg grating in the second waveguide film layer, the other part of light is reflected back to the cylindrical lens by the Bragg grating, and then is emitted into the end B of the circulator through the collimating mirror and then is emitted out from the end C of the circulator and input into the photoelectric detector.
The tunable laser applies any one of the thermo-optically modulated planar waveguide type Bragg gratings, and comprises a semiconductor laser, a collimating lens, a cylindrical lens and a thermo-optically modulated planar waveguide type Bragg grating; the semiconductor laser, the collimating lens, the cylindrical lens and the thermo-optic modulation planar waveguide type Bragg grating are sequentially arranged; the laser emitted by the semiconductor laser sequentially passes through the collimating lens and the cylindrical lens and then is emitted into the second waveguide film layer of the thermo-optically modulated planar waveguide Bragg grating, and the laser is emitted after passing through the Bragg grating in the second waveguide film layer.
Compared with the prior art, the beneficial effects of the utility model are as follows: the method is characterized in that a-Si, a-SiH, a-SiGeH and a-GeH materials are adopted to prepare a planar waveguide, ultraviolet or femtosecond laser is used for photoetching a Bragg grating on a waveguide layer to prepare a thermo-optic modulation planar waveguide type Bragg grating, the large thermo-optic coefficients of the a-Si, a-SiH, a-SiGeH and a-GeH materials are utilized, the change of narrow-band reflection wavelength in a large wavelength range is generated by controlling the temperature change, and the thermo-optic modulation planar waveguide type Bragg grating with the structure can be used for manufacturing micro OCM, TOF and tunable lasers.
Drawings
The accompanying drawings, which are described herein to provide a further understanding of the application, are included in the following description:
fig. 1 is a schematic structural diagram of a thermo-optic modulation planar waveguide bragg grating according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an optical path of a micro OCM or TOF manufactured by using a thermo-optic modulation planar waveguide bragg grating according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an optical path of a tunable laser manufactured by using a thermo-optic modulation planar waveguide bragg grating according to an embodiment of the present invention.
Detailed Description
Referring to fig. 1, the thermo-optically modulated planar waveguide type bragg grating of the embodiment includes a planar waveguide body and a waveguide heating device; the planar waveguide body comprises an optical substrate 1 and a waveguide layer 2, wherein the waveguide layer 2 comprises a first waveguide film layer 21, a second waveguide film layer 22 and a third waveguide film layer 23 which are sequentially laminated and plated on the optical substrate 1, and the refractive index of the second waveguide film layer 22 is respectively greater than that of the first waveguide film layer 21 and that of the third waveguide film layer 23; the first waveguide film layer 21, the second waveguide film layer 22 and the third waveguide film layer 23 are all formed by any one of a-Si, a-SiH, a-SiGeH and a-GeH waveguide material, and the Bragg grating 221 is photoetched on the second waveguide film layer 22; the waveguide heating device heats the waveguide layer.
Further, the bragg grating 221 is formed by ultraviolet or femtosecond laser lithography.
Further, the second waveguide film layer 22 is a single-mode structure.
Further, the first waveguide film layer 21, the second waveguide film layer 22 and the third waveguide film layer 23 are formed by plating at different evaporation rates or at different temperatures of the optical substrate 1.
Further, the waveguide heating device can be a visible light LED core bar 7 arranged above the waveguide layer to irradiate the waveguide layer, and the waveguide layer absorbs light to heat. Of course, an electromagnetic heating layer or a heating resistor sheet can also be arranged at the bottom of the optical substrate to heat the waveguide layer.
Referring to fig. 2, the micro OCM or TOF employs any one of the above-mentioned thermo-optically modulated planar waveguide bragg gratings, which includes a photodetector 6, a circulator 5, a collimating mirror 4, a cylindrical lens 3, and a thermo-optically modulated planar waveguide bragg grating; after a light source emission light signal enters from the end a of the circulator 5, the light signal exits from the end B of the circulator 5, and then enters the second waveguide film layer 22 of the thermo-optic modulation planar waveguide bragg grating through the collimating mirror 4 and the cylindrical lens 3 in sequence, a part of light exits after passing through the bragg grating 221 in the second waveguide film layer 22, the other part of light is reflected back to the cylindrical lens 3 by the bragg grating 221, and then enters the end B of the circulator 5 through the collimating mirror 4, exits from the end C of the circulator 5 and enters the photodetector 6.
The tunable laser applies any one of the above-mentioned thermo-optically modulated planar waveguide type bragg gratings, and comprises a semiconductor laser 7, a collimating mirror 4, a cylindrical lens 3 and a thermo-optically modulated planar waveguide type bragg grating; the semiconductor laser 7, the collimating lens 4, the cylindrical lens 3 and the thermo-optic modulation planar waveguide type Bragg grating are sequentially arranged; the laser emitted by the semiconductor laser 7 sequentially passes through the collimating lens 4 and the cylindrical lens 3 and then is incident on the second waveguide film layer 22 of the thermo-optically modulated planar waveguide type bragg grating, and the laser is emitted after passing through the bragg grating 221 in the second waveguide film layer 22.
The utility model discloses a theory of operation:
the reflection wavelength of The fiber can move with The temperature change due to The thermal expansion coefficient and The thermo-optic effect of The fiber, and The relationship between them is given in The document "The reflection of temperature on reflected wavelength shift of fiber Bragg grating" (LASER TECHNOLOGY Vo1.28.No.3June, 2004):
the bragg equation for a fiber grating is:
λ c ＝2n eff Λ (1)
in the formula, λ c Is Bragg reflection light wave center wavelength, n, of fiber grating eff To reflect the effective index of light from the fiber grating, Λ is the period of the grating. When the environmental temperature changes, if the stress action is not considered, the variation form of the Bragg equation obtained by the formula (1) is as follows:
wherein (Δ n) eff ) ep Indicating the elasto-optic effect caused by thermal expansion;
showing the waveguide effect due to the change in the core diameter of the fiber caused by thermal expansion.
The compound is represented by the following formula (1) or (2):
in the formula (I), the compound is shown in the specification,
the thermo-optic coefficient of the fiber grating is represented by xi;
the thermal expansion coefficient of the fiber grating is represented by alpha. Thus equation (3) can be written as:
in the formula (I), the compound is shown in the specification,
η is the temperature sensitivity coefficient of the fiber grating. Since the influence of the elasto-optic effect and the waveguide effect on the temperature sensitivity coefficient η of the fiber grating is much smaller than the thermo-optic coefficient ξ and the thermal expansion coefficient α, their influence on η can be ignored, and thus the equation (5) becomes:
η＝ξ+α (6)
namely, it is
If the influence of temperature on the thermal expansion coefficient alpha and the thermo-optic coefficient xi is not considered, the temperature sensitivity coefficient eta of the fiber grating is a constant, and can be obtained by the formula (7), and the central wavelength of the reflected wave of the fiber grating is relative to the drift quantity
Proportional to the temperature change Δ T, the proportionality coefficient is the temperature sensitivity coefficient η. For Ge-doped quartz fiber, xi is about 9.9x10 -6 /℃，α≈0.55x10 -6 /° C, so η ≈ 10.45x10 -6 /℃。
On the other hand, if the a-Si: H has a thermo-optic coefficient which is more than 20 times of that of the optical fiber, if the a-Si: H planar waveguide is processed by adopting ultraviolet or femtosecond laser and simulating the process similar to the process of manufacturing the fiber Bragg grating by laser, a one-dimensional planar waveguide type Bragg reflection grating, namely laser output from the collimator, is manufactured, the laser is coupled into the a-Si: H single-mode planar waveguide by adopting a cylindrical lens in the one-dimensional direction, and freely advances in the other direction by collimated light, the fiber Bragg formula calculation is also suitable for the Bragg grating of the planar waveguide.
The problem of thermal expansion coefficient is neglected by using a fiber Brag grating calculation formula, and the thermo-optic coefficient is an average value of high temperature and low temperature (300-480K): (230+ 290)/2-260
Assuming a temperature change of 200 degrees, the wavelength variation range around 1550nm is 0.000026 × 200 × 1550 ═ 80.6nm
The general optical fiber Bragg grating is photoetched to be 10mm long, and the reflection wavelength bandwidth is 0.5 nm-2 nm, and can also be 0.1 nm. If the bandwidth of 0.1nm, namely 13GHz, can be achieved, the measurement precision is good as the common spectrum measurement. H thermo-optic coefficient of a-Ge has not been found yet for the moment, but the thermo-optic coefficient of Ge is 462, which is more than 2 times that of Si 200.
If the simple reasoning shows that the thermo-optic coefficient of a-Ge to H is more than 2 times of the thermo-optic coefficient of a-Si to H, the planar waveguide Bragg grating of a-GeH can cover the C + L waveband after the shift amount of the reflection wavelength is more than 160nm when the temperature of the planar waveguide Bragg grating of a-GeH is changed at 200 ℃.
In addition, the transmission bands of a-SiH and a-GeH are reduced to 800nm, so that the near infrared band can be adopted.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. The thermo-optic modulation planar waveguide type Bragg grating is characterized in that: the planar waveguide heating device comprises a planar waveguide body and a waveguide heating device; the planar waveguide body comprises an optical substrate and a waveguide layer, wherein the waveguide layer comprises a first waveguide film layer, a second waveguide film layer and a third waveguide film layer which are sequentially laminated and plated on the optical substrate, and the refractive index of the second waveguide film layer is respectively greater than that of the first waveguide film layer and that of the third waveguide film layer; the first waveguide film layer, the second waveguide film layer and the third waveguide film layer are all formed by any one of a-Si, a-SiH, a-SiGeH and a-GeH waveguide material, and the second waveguide film layer is used for photoetching Bragg gratings; the waveguide heating device heats the waveguide layer.
2. The thermo-optically modulated planar waveguide type bragg grating as claimed in claim 1, wherein: the Bragg grating is formed by ultraviolet or femtosecond laser photoetching.
3. The thermo-optically modulated planar waveguide type bragg grating as claimed in claim 1, wherein: the second waveguide film layer is of a single-mode structure.
4. The thermo-optically modulated planar waveguide type bragg grating as claimed in claim 1, wherein: the first waveguide film layer, the second waveguide film layer and the third waveguide film layer are plated and formed at different evaporation rates or different temperatures of the optical substrate.
5. The thermo-optically modulated planar waveguide type bragg grating as claimed in claim 1, wherein: the waveguide heating device is an electromagnetic heating layer or a heating resistance sheet which is arranged at the bottom of the optical substrate and heats the waveguide layer; or the waveguide heating device is used for irradiating the waveguide layer by arranging the visible light LED core bar above the waveguide layer, and the waveguide layer absorbs light for heating.
6. A micro OCM or TOF for use with a thermo-optically modulated planar waveguide bragg grating according to any one of claims 1 to 5, wherein: the device comprises a photoelectric detector, a circulator, a collimating mirror, a cylindrical lens and a thermo-optic modulation planar waveguide type Bragg grating; the light source emitting light signal is emitted from the end A of the circulator and then from the end B of the circulator, and then is emitted into the second waveguide film layer of the thermo-optic modulation planar waveguide Bragg grating through the collimating mirror and the cylindrical lens in sequence, one part of light is emitted after passing through the Bragg grating in the second waveguide film layer, the other part of light is reflected back to the cylindrical lens by the Bragg grating, and then is emitted into the end B of the circulator through the collimating mirror and then is emitted out from the end C of the circulator and input into the photoelectric detector.
7. A tunable laser using the thermo-optically modulated planar waveguide type Bragg grating according to any one of claims 1 to 5, wherein: the device comprises a semiconductor laser, a collimating mirror, a cylindrical lens and a thermo-optic modulation planar waveguide type Bragg grating; the semiconductor laser, the collimating lens, the cylindrical lens and the thermo-optic modulation planar waveguide type Bragg grating are sequentially arranged; the laser emitted by the semiconductor laser sequentially passes through the collimating lens and the cylindrical lens and then is emitted into the second waveguide film layer of the thermo-optically modulated planar waveguide Bragg grating, and the laser is emitted after passing through the Bragg grating in the second waveguide film layer.
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