RU2627017C1 - Method for manufacturing waveguide in volume of plate made of porous optical material - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method for manufacturing a waveguide in the volume of a plate made of porous optical material transparent for the wavelength of laser radiation consists in moving a focused laser beam relative to the plate or the plate relative to the focused laser beam in the plane of waveguide formation until the waveguide is formed. The pulse duration of the laser radiation is selected not more than 200 fs at a pulse repetition rate of at least 300 kHz, the energy density in the pulse is not less than 8⋅10³ J/cm² and not more than 12⋅10³ J/cm², and the movement speed of the focused laser beam relative to the plate or the plate relative to the beam is not less than 0.125 mm/s and not more than 3.750 mm/s, wherein the plate is used with thermo-packed layers with thickness of not more than 30 mcm and not less than 5 mcm on wide plate surfaces.

EFFECT: creation of a volumetric waveguide with a difference in the refractive index of the core-sheath values exceeding 0,12, with a shortened manufacturing time.

10 dwg

Description

The invention relates to a technology for manufacturing optical waveguides, that is, light-conducting and light-controlling structures located in a glass volume and can be used in devices for transmitting, processing, and controlling an optical signal in optoelectronics.

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4493-4502; Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. №18 p. 1815-1821). Увеличение значения показателя преломления на траектории перемещения сфокусированного лазерного пучка располагается в диапазоне 1÷5⋅10^-3 и позволяет поддерживать волноводные свойства вдоль траектории, которая выполняет роль сердцевины волновода. Данный способ может быть реализован в двух режимах изготовления в зависимости от состава стекла.There is a known method of manufacturing optical waveguides based on a change in the refractive index under local exposure to a laser beam with a wavelength focused on the glass, focused on the volume of the laser beam for which the glass is optically transparent, with a femtosecond pulse duration up to a diffraction-limited spot (Jason R. Grenier,

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4,493-4,502; Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. No. 18 p. 1815-1821). An increase in the value of the refractive index on the trajectory of the focused laser beam is in the range of 1 ÷ 5⋅10 ^-3 and allows maintaining waveguide properties along the trajectory, which acts as the core of the waveguide. This method can be implemented in two manufacturing modes, depending on the composition of the glass.

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4493-4502). Другой режим изготовления реализуется на лазерных излучателях с энергией импульса в районе нДж при частоте повторений импульса в МГц диапазоне (Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. №18 p. 1815-1821). Локальное изменение показателя преломления в обоих режимах основано на механизме нелинейного поглощения (D. М. Krol. Femtosecond laser modification of glass // Journal of Non-Crystalline Solids, 2008, №354, pp. 416-424.).One manufacturing mode is implemented using a laser system with an amplifier in which the energy in the pulse is mJ and the pulse repetition rate is in the kHz range (Jason R. Grenier,

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4493-4502). Another manufacturing mode is implemented on laser emitters with a pulse energy in the region of NJ at a pulse repetition rate in the MHz range (Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. No. 18 p. 1815-1821). A local change in the refractive index in both modes is based on the nonlinear absorption mechanism (D. M. Krol. Femtosecond laser modification of glass // Journal of Non-Crystalline Solids, 2008, No. 354, pp. 416-424.).

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4493-4502) позволяет наиболее эффективно записывать объемные волноводы на силикатных стеклах, а использование лазерных источников (Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. №18 p. 1815-1821) - на боросиликатных, сульфидных и свинцовых стеклах. Увеличение показателя преломления в обоих режимах не превышает значение 1÷5⋅10^-3. Размер фокального пятна сфокусированного пучка лазерного излучения с фемтосекундной длительностью импульса, обеспечивающего нелинейное поглощение в объеме стекла, составляет в обоих режимах 2÷3 мкм и задает диаметр сердцевины объемного волновода. Волноводные свойства объемного волновода с диаметром сердцевины 2÷3 мкм при показателе преломления, превышающем показатель преломления окружающего сердцевину объемного волновода на величину 1÷5⋅10^-3, слабы, и это приводит к потерям от 50% и более передаваемого по объемному волноводу оптического сигнала, рассеиваемого в окружающую среду, т.е. в оболочку объемного волновода. Кроме того, слабые волноводные свойства не позволяют создавать изогнутые объемные волноводы с малым радиусом кривизны оптического качества. Рассеивание передаваемого оптического сигнала и ограничения на радиус кривизны изогнутых объемных волноводов являются основными недостатками способа изготовления волновода в объеме стекла в обоих режимах.Using Laser Systems with an Amplifier (Jason R. Grenier,

A. Fernandes, Peter R. Herman. Femtosecond laser writing of optical edge filters in fused silica optical waveguides // OPTICS EXPRESS. 2013. Vol. 21. No. 4. p. 4493-4502) allows the most efficient recording of bulk waveguides on silicate glasses, and the use of laser sources (Jaw-Luen Tang, Chien-Hsing Chen, Ting-Chou Chang. Fabrication and characterization of a fused silica-based optical waveguide with femtosecond fiber laser pulses // Microsyst Technol 2012. No. 18 p. 1815-1821) - on borosilicate, sulfide and lead glasses. The increase in refractive index in both modes does not exceed the value of 1 ÷ 5⋅10 ^-3 . The focal spot size of a focused laser beam with a femtosecond pulse duration, which provides nonlinear absorption in the glass volume, is 2–3 μm in both modes and sets the diameter of the core of the volume waveguide. The waveguide properties of a volume waveguide with a core diameter of 2–3 μm with a refractive index exceeding the refractive index of the volumetric waveguide surrounding the core by 1–5⋅10 ^-3 are weak, and this leads to losses of 50% or more of the optical signal transmitted through the volumetric waveguide dispersed into the environment, i.e. into the sheath of a volumetric waveguide. In addition, weak waveguide properties do not allow the creation of curved volume waveguides with a small radius of curvature of optical quality. The scattering of the transmitted optical signal and the restrictions on the radius of curvature of curved volumetric waveguides are the main disadvantages of the method of manufacturing a waveguide in a glass volume in both modes.

A known method of manufacturing a volumetric waveguide, which is selected by the authors as a prototype (RF patent No. 2531222, IPC: G02B 6/10, C03C 23/00, H01P 11/00, priority date 07/12/2013, publication date 10/20/2014). A method of manufacturing a volumetric waveguide by local laser irradiation of a plate made of a material transparent to laser radiation with a refractive index equal to the refractive index of the core of the waveguide but greater than the refractive index of its shell consists in moving the focused laser beam relative to the plate or plate relative to the focused laser beam until the formation of the waveguide and subsequent heat treatment of the plate with the waveguide in ne and. In this case, before the formation of the waveguide, a plate of porous optical material is placed in a chamber in which at room temperature the relative air humidity is maintained not lower than 60% and not higher than 80% for at least 72 hours, but not more than 96 hours. Local laser exposure is carried out by a focused laser beam into the plane of the layer lying at a depth equal to 1/4 of the plate thickness, with a power density of not less than 1.5⋅10 ⁴ W / cm ² and not more than 2.5⋅10 ⁴ W / cm ² . The focus of the focused laser beam relative to the plate or plate relative to the focused laser beam is carried out at a speed of not less than 3 μm / s, but not more than 20 μm / s, repeatedly until the formation of the waveguide. Then the plate with the waveguide is subjected to heat treatment at a temperature of not lower than 870 ° C, but not higher than 890 ° C for at least 10 minutes and no more than 20 minutes, and the plate with the waveguide is heated to a temperature of not higher than 140 ° C at a speed of not more than 5 ° C / min, cool the plate with the waveguide after heat treatment by turning off the furnace. The method is based on the mass transfer of fragments of finely dispersed amorphous silica hydrated by water molecules contained in the pores and channels of the PS plate under the action of a secondary constant electric field due to the appearance of a charge distribution that occurs under the influence of an alternating electric field of laser radiation, which polarizes the molecules of substances in the pores and PS channels in the field of laser radiation (Kostyuk GK, Sergeev MM, Yakovlev EB The nature of the modified areas in the volume of glass induced by laser radiation with a wavelength weakly absorbed by the glass / g. Promising materials. 2013. No. 9. C: 43-53; Kostyuk, G., M. Sergeev, and E. Yakovlev, The processes of modified microareas formation in the bulk of porous glasses by laser radiation. Laser Physics, 2015.25 (6): p. 066003.). The heat treatment carried out after creating a volumetric waveguide with restrictions on the heating rate, duration and temperature of the process is aimed at ensuring the conservation of the volumetric waveguide, stabilization of its optical characteristics by stabilizing the properties of the PS, which during heat treatment turns into quartzoid glass. Heat treatment was carried out in the temperature range of 870-890 ° C for 10-20 minutes. The disadvantages of the prototype method include the impossibility of creating a difference in the refractive index of the core-shell, exceeding 10 ^-1 , i.e. the inability to reduce the loss of the optical signal transmitted through the volumetric waveguide, and in fact the inability to create a volumetric waveguide of optical quality. The specified disadvantage of the prototype method limits the use of a volumetric waveguide in the volume of glass in optoelectronics. Another disadvantage of the prototype method is the need for heat treatment after creating a volumetric waveguide, aimed at ensuring the conservation of the volumetric waveguide and the stabilization of optical characteristics over time. Carrying out heat treatment increases the duration of the manufacture of a volumetric waveguide.

The objective of the invention is the creation of a volumetric waveguide with a difference in the values of the refractive indices of the core-cladding in excess of 0.12, while reducing the manufacturing time.

The essence lies in the fact that in the method of manufacturing a volumetric waveguide, a focused laser beam with a pulse duration of not more than 200 fs is moved in a plate volume of a porous optical material in a volume of a pulse of at least 300 kHz with an energy density of at least 8⋅10 ³ J / cm ² and not more than 12⋅10 ³ J / cm ² , with a travel speed of not less than 0.125 mm / s and not more than 3.750 mm / s, relative to the plate or plate relative to the focused laser beam, using a plate of porous optical material with thermally densified layers with a thickness of not more than 30 microns and not less than 5 microns on wide surfaces of the plate.

The choice for the formation of a volumetric waveguide plate (PS) with thermally sealed layers on wide surfaces of the plate was due to studies of similar plates, in which it was shown that thermally sealed layers protect and preserve the developed internal structure of PS during storage of plates with thermally sealed layers in air (Sergeev M. M., Kostyuk GK, Zakoldaev RA, Yakovlev EB Laser passivation of porous glass for protection against chemical degradation and aging. Physical chemistry of the surface and protection of materials. 2015. V. 51. No. 3. P. 314 - 322).

In the absence of thermally densified layers, porous glass (PS) plates when stored in air not only lose their transparency and darken due to adsorption of water molecules and organic compounds contained in air, but also with increasing storage time, the pore surface decreases with an increase in their radii, t .e. degradation of the PS structure occurs.

When heat treating PS plates in a furnace when heated to temperatures of 900-1100 ° C, called sintering (Leko, V.K., O.V. Mazurin, and B.G. Varshal, Properties of quartz glass. 1985: Science. Leningrad. ), based on the densification of the branched system of pores and channels of PSs and aimed at the long-term stabilization of the optical properties of PSs, the developed internal structure of PSs is not preserved.

Heat-sealed layers, occupying no more than 1-2% of the volume of PS plates, are designed to preserve and protect the developed internal structure of PS during storage and operation of PS plates with devices and based on these plates.

When a bulk waveguide is formed in a PS plate with thermally densified layers, the difference in the refractive indices of the core-cladding increases as the porosity of the used PS increases, since the core of the waveguide is a fully densified PS - quartzoid glass with a refractive index of ~ 1.46, and the shell - porous glass, refractive index which is determined by the porosity of the PS plate, to which the concept of optical material can be applied only in the case of high transparency of the plate (transmittance τ in the visible and near-IR spectral ranges should exceed 0.8 for wafers 1.2–2 mm thick). The porosity of the porous optical material can vary between 0.25-0.36. This range of porosity corresponds to a range of values of refractive index 1.34-1.28 (Kostyuk G.K., Veiko V.P., Roskova G.P., Tsekhomskaya T.S., Yakovlev E.B. Refractive indices of high-silica porous glasses with different porosity // Physics and chemistry of glass. 1989. T. 15. No. 2. S .: 231-238.). In all experiments to create a volumetric waveguide, PS plates with a thickness of 1.5 mm and a porosity of 0.30 cm ³ / cm ³ and, respectively, with a refractive index of 1.31 were used.

The restrictions on the pulse duration, pulse repetition rate, energy density per pulse, and also the speed of the focused beam relative to the plate or plate relative to the beam indicated in the claims were determined during experiments to create a volumetric waveguide in the volume of a PS plate with thermally densified layers.

The invention is illustrated by figures, where

in FIG. 1 is a diagram of a device for implementing a method for manufacturing a volumetric waveguide in a substation;

in FIG. Figure 2 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 20 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 500 μm from the surface of a plate with an energy density of 10–10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 350 kHz, and a PS plate relative to the focused laser beam 1 mm / s. The volumetric waveguide was taken in transmitted light with a magnification of 100 × using a Carl Zeiss Axio Imager A1 microscope. In the photograph, one can distinguish a waveguide core equal to 4 μm, the refractive index of which is equal to the refractive index of a quartzoid (n ~ 1.46), and the shell surrounding the core with a refractive index n ~ 1.31 corresponding to the porosity of the layer in which the volume waveguide was formed (δ = 0.3 cm ³ / cm ³ ). The shape of the volume waveguide in the photograph indicates a sharp core – cladding boundary. The difference in refractive indices of the core-shell is 0.15;

in FIG. Figure 3 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 25 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 620 μm from the surface of a plate with an energy density of 11.4 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 220 fs, a pulse repetition rate of 350 kHz, and a PS plate moving relative to the focused laser beam 0.8 mm / s. A photograph of a volumetric waveguide was performed in transmitted light with a magnification of 100 ×. The photograph attracts attention to the violation of the structure of the volume waveguide;

in FIG. Figure 4 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 28 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 300 μm from the surface of a plate with an energy density of 10 10 ³ J / cm ² in a focused laser beam with a pulse duration of 160 fs, a pulse repetition rate of 280 kHz, and a PS plate moving relative to the focused laser beam 2.4 mm / s. A photograph of a volumetric waveguide was performed in transmitted light with a magnification of 100 ×. A layer is visible in the photograph surrounding the volume waveguide with altered optical characteristics, i.e. partial heat sealing layer;

in FIG. Figure 5 shows a computer printout of a photograph of a volume waveguide in a PS plate with thermally densified layers 22 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 400 μm from the surface of a plate with an energy density of 6.4 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 340 kHz, and a PS plate relative to the focused laser beam 3.2 mm / s. In a photograph of a volumetric waveguide made in transmitted light with a magnification of 100 ×, the boundary between the core-cladding in the structure of the volumetric waveguide is almost invisible, which indicates that thermal sealing of the core did not occur;

in FIG. Figure 6 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 20 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 500 μm from the surface of a plate with an energy density of 14.2 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 150 fs, a pulse repetition rate of 340 kHz, and a PS plate relative to the focused laser beam 0.5 mm / s. In a photograph of a volumetric waveguide made in transmitted light with a magnification of 100 ×, the structure of the volumetric waveguide is not visible. The formed structure is a series of partially overlapping areas of spherical shape, the diameter of which varies within 10% along the formed structure;

in FIG. Figure 7 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 15 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 250 μm from the surface of a plate with an energy density of 10.8 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 340 kHz, and a PS plate relative to the focused laser beam 0.1 mm / s. In a photograph of a volumetric waveguide made in transmitted light with a magnification of 100 ×, numerous violations are observed in the integrity of the core of the volumetric waveguide;

in FIG. Figure 8 shows a computer printout of a photograph of a volumetric waveguide in a PS plate with thermally densified layers 20 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 400 μm from the surface of a plate with an energy density of 8.8 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 350 kHz, and a PS plate relative to the focused laser beam 3.9 mm / s. In a photograph of a volumetric waveguide made in transmitted light with a magnification of 100 ×, the core-cladding interface is practically indistinguishable, which most likely indicates that complete thermal sealing in the core of the region of formation of the volumetric waveguide did not occur;

In FIG. Figure 9 shows a computer printout of a photo of a volumetric waveguide in a PS plate with thermally densified layers 38 μm thick on wide surfaces of a PS plate. A volume waveguide was formed at a depth of 300 μm from the surface of a plate with an energy density of 9–10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 350 kHz, and a PS plate relative to the focused laser beam 1.6 mm / s. A photograph of a volumetric waveguide was performed in transmitted light with a magnification of 100 ×. In the photograph, the core – cladding boundary is weakly expressed in some parts of the volume waveguide.

In FIG. Figure 10 shows a computer printout of a photograph of a volume waveguide in a PS plate with thermally densified layers 4 μm thick on wide surfaces of a PS plate. A volumetric waveguide was formed at a depth of 250 μm from the surface of a plate with an energy density of 11.2 × 10 ³ J / cm ² in a focused laser beam with a pulse duration of 180 fs, a pulse repetition rate of 320 kHz, and a PS plate relative to the focused laser beam 1.5 mm / s. A photograph of a volumetric waveguide was performed in transmitted light with a magnification of 100 ×. The photograph shows a discontinuity in the structure of the volume waveguide in some areas along its line.

A device for implementing the proposed method (Fig. 1) contains: a pulsed ytterbium fiber laser 1 with a wavelength of λ = 1.03 μm, a pulse duration of 150-350 fs, a pulse repetition rate of 0-2 MHz, with a side supply of laser 2, with the device unit on KDP 3 crystal base for converting laser radiation to the second harmonic with λ = 0.515 μm, plate 4 mounted at an angle of 45 to the optical axis of the laser, micro lens 5 with a magnification of 10 ×, numerical aperture 0.25 and focal length 4.75 ± 0.25 mm, behind which is perpendicular laser optical axis positioned etsya PS plate 6, attached to the coordinate table 7 provided movably along the axes X and Y at a speed of 0.1-5.0 mm / s, and along the axis Z, which coincides with the laser optical axis with the displacement accuracy ± 1.0 microns. Behind plate 6, a lens 8 is mounted that collects radiation transmitted through the PS 6 plate to the Solo 2M optical power meter (IOM) (with a pyroelectric with a pyroelectric power detector UP 19K - 110F - H9 with an accuracy of 1% of the measured value and a noise power equivalent of 1 mW) 9 with an energy detector connected to a synchronization unit 10, providing simultaneous on / off power supply 2 of the laser 1 with the beginning and end of the movement of the coordinate table 7. The second power meter Solo 2M 11 is located behind the plate 4 and so it is connected to the synchronization unit 10. As a synchronization unit 10, a personal computer (PC) is used.

The device operates as follows. Laser radiation 1 passes through a device based on a KDP 3 crystal and plate 4 mounted at an angle of 45 ° to the optical axis of laser 1, with up to 5% of the radiation energy being reflected from plate 4 and transferred to IOM 11. The radiation transmitted through plate 4 is focused by the lens 5 into the plane of formation of the volume waveguide into a layer located at a certain (predetermined) depth of the PS plate 6. Simultaneously with the inclusion of laser 1, the coordinate table 7 begins to move along one of the X or Y coordinates, satisfying the limitations of the claims Nia. In this case, part of the radiation transmitted through the generated volumetric waveguide is recorded by IOM 9 located behind the lens 8 mounted behind the PS plate 6. A part of the radiation reflected by the plate 4 installed at an angle of 45 ° to the optical axis of the laser is used to control the power generating the volumetric radiation waveguide. The moment of the end of the formation of the volumetric waveguide is recorded by the IOM 9. The criterion for the end of the formation of the volumetric waveguide was the termination of the increase in the power of the transmitted radiation on the IOM 9. At the time the termination of the increase in power, the power supply unit of the laser 1 is turned off, and at the same time, the coordinate table 7 stops moving through the synchronization unit 10.

The size of the volume waveguide is controlled by changing the size of the exposure area, the energy density in the pulse, which is determined by the power of the radiation incident on the PS 6, the pulse duration and the pulse repetition rate, and also by changing the scanning speed.

The minimum size of a volume waveguide that can be manufactured by the claimed method is determined by the divergence of the radiation beam of the used laser 1 and the optical characteristics of the micro-lens 5 and on the equipment described in the description can be ~ 4 μm, which corresponds to a single-mode waveguide structure.

The difference in the refractive indices of the core-cladding in the bulk waveguide is determined by the porosity of the used PS corresponding to the definition of an optically transparent material, and for PS with the porosity δ = 0.3 cm ³ / cm ³ used in experiments on creating a volume waveguide, it reaches 0.15. A volume waveguide, consisting of a thermally densified core, whose refractive index equal to 1.46 exceeds the sheath refractive index (n ~ 1.31) by 0.15, is capable of transmitting radiation with lower losses compared to the waveguide created according to the prototype method. In other words, the quality of the waveguide created according to the claimed method exceeds the quality of the waveguide created according to the prototype method. The relationship between the porosity of PS plates and the refractive index is valid for all types of PS that meet the definition of an optically transparent material.

A volume waveguide was formed in the volume of a PS wafer with heat-sealed layers with a thickness of 20 μm corresponding to the thickness claimed in the claims, in accordance with the parameters of the claims (Fig. 2), the difference in refractive indices for which the core-shell corresponds to a value of 0.15.

When forming volumetric waveguides in substrates with thermally densified layers, provided that at least one of the parameters given in the claims is violated, for example, FIG. 3 (pulse duration 250 fs), FIG. 4 (pulse repetition rate 270 kHz), FIG. 5 (energy density 6 · 10 ³ J / cm ² ), FIG. 6 (energy density 14 · 10 ³ J / cm ² ), FIG. 7 (the speed of movement V of the PS plate with thermally densified layers relative to the focused laser beam is 0.1 mm / s), FIG. 8 (velocity V ~ 3.9 mm / s), a violation of the waveguide structure is characteristic; a layer with partial thermal sealing surrounding the waveguide; lack of a core-shell separation boundary; the formation of a structure, which is a series of partially overlapping areas of a spherical shape, the diameter of which varies within 10% along the formed structure; violation of the integrity of the core of the volumetric waveguide and the absence of complete thermal sealing in the core of the volumetric waveguide.

When violating the restrictions on the thickness of the heat-sealed layers of the PS plate, for example, FIG. 9 (thickness 38 μm) and FIG. 10 (thickness 4 μm), in the first case, the core-cladding boundary of the volume waveguide is weakly expressed in some areas, and in the second case, the discontinuity of the structure of the volume waveguide in some areas along its line is noticeable.

Based on the foregoing, the claimed combination allows the formation of a volumetric waveguide, the difference in refractive indices of the core-clad in which is 0.15, i.e. waveguide, the optical quality of which exceeds the quality of the waveguide manufactured according to the prototype method. The exclusion of the heat treatment operation reduces the manufacturing time of the volume waveguide.

Claims (1)

A method of manufacturing a waveguide in the volume of a plate of a porous optical material transparent to the wavelength of the laser radiation, which consists in moving the focused laser beam relative to the plate or plate relative to the focused laser beam in the plane of the waveguide formation until the waveguide is formed, characterized in that the laser pulse duration choose no more than 200 fs at a pulse repetition rate of at least 300 kHz with an energy density in the pulse of at least 8 March ¹⁰ J / cm ² and not more 12⋅10 ³ J / cm ^2, and the speed of the focused laser beam relative to the plate or plates relative to the beam is not less than 0.125 mm / s and not more than 3,750 mm / s, this time with plate thermally sealed layers with a thickness of not more than 30 microns and not less than 5 microns on wide surfaces of the plate.

Images