KR102614185B1 - Polymer optical ic-based laser integrated two-dimensional beam scanner and manufacturing method thereof - Google Patents

Abstract

Optical phased array structures are being researched to develop small fixed beam scanners needed in fields such as lidar, free space communication, and biophotonics. Based on the excellent optical properties of fluorine-substituted polymers, we propose a polymer optical waveguide OPA-based beam scanner that can operate at low power and emit high output power. Unlike OPA based on silicon photonics, on which much research is currently being conducted, polymer OPA is capable of stable phase control at low power. 2D beam scanning operation was confirmed using an OPA manufactured by integrating a tunable laser using a polymer Bragg grating, and from this, a light source integrated polymer OPA beam scanner structure was proposed.

Description

Polymer optical IC-based laser integrated two-dimensional beam scanner and manufacturing method thereof {POLYMER OPTICAL IC-BASED LASER INTEGRATED TWO-DIMENSIONAL BEAM SCANNER AND MANUFACTURING METHOD THEREOF}

Various embodiments relate to a polymer optical IC-based laser integrated two-dimensional beam scanner and a manufacturing method thereof. Specifically, a small beam scanner capable of scanning a laser beam extending in space through phase control of light waves without a mechanical driver. and its manufacturing method.

By forming optical output in the form of an array using an optical waveguide, beam scanning can be performed through phase distribution control. As a result, stable operation is possible as there are no moving parts such as rotating mirrors used in existing mechanical beam scanners, and there are no frame rate limitations due to inertia. In addition, optical IC technology will enable the development of modules that are both miniaturized and low-cost, and will enable innovative development of LiDAR technology required for self-driving cars and unmanned devices. In addition, OPA (optical phased array) beam scanner technology is a necessary technology in various fields such as free-space optical link, image projection, and lens-less imaging.

Research on OPA beam scanners has become active as it has been highlighted that the diffraction angle of output light from optical waveguides can be greatly expanded using silicon photonics technology and the beam scanning angle can be increased by reducing the gap between waveguides. Considering the far-field of the beam output from the OPA device, reducing the pitch of the silicon optical waveguide array increases the scanning range as the position of the side lobe moves away from the main lobe, Increasing the number of channels of an array waveguide can improve scanning resolution by reducing the divergence angle of the main beam. An OPA device with a waveguide array of 1024 channels and an output waveguide pitch of 2 um was manufactured through a CMOS process, and a beam scanner with a diffusion angle of 0.03 and a scanning angle of 45° was implemented. A method using an aperiodic waveguide array was also proposed to improve the scanning angle to 90°. In order to obtain a high frame rate using a beam scanner, the response speed of the phase modulator must be improved. To this end, the charge density change due to the applied voltage in the diode structure made of III-V group compound such as InAlGaAs is required. The phase modulator used was manufactured and a response speed of microseconds was demonstrated. However, the light absorption phenomenon that occurs with phase change is a problem that must be overcome.

In order to detect objects located at a distance through a LiDAR module consisting of an OPA element and a short pulse laser, the output of the beam scanner must be greater than +10 dBm. In this case, the nonlinear optical characteristics of the silicon material are It raises tricky problems. Additionally, as the number of OPA channels increases, the high heat transfer characteristics of silicon devices cause thermal crosstalk in adjacent phase modulators, making it difficult to control stable phase distribution. In addition, in silicon devices with narrow optical waveguide widths, deviations in output phase occur due to subtle changes in pattern width that are difficult to avoid during the manufacturing process. To correct this, measure the phase distribution in advance and apply phase modulation corresponding to each output angle. A voltage look-up table (LUT) must be formed in advance. For this reason, when using an FPGA with low memory, the number of beam scanning points was limited to 200.

Compared to silicon optical waveguides, OPA, an optical waveguide using silicon nitride material, has a relatively wide optical waveguide due to a small refractive index contrast, but the optical nonlinear characteristics of the material are weak, so it is suitable for handling high-output light. However, there is a disadvantage in that high driving power is required to control the phase modulator array due to the thermo-optic coefficient being as low as 1/10 compared to silicon. Considering the characteristics of these materials, a hybrid type device in which only the phase modulator array portion is made of silicon was also proposed based on the silicon nitride optical waveguide structure.

Meanwhile, polymer materials are used in the development of optical devices such as variable optical attenuators, tunable lasers, and optical sensors based on their high thermo-optic effects and excellent thermal confinement effects. It has been used. In particular, the wavelength-tunable laser using a Bragg grating as a polymer optical waveguide can tune the Bragg reflected wavelength over a wide range using a simple device structure based on the high thermo-optic effect of polymer, and has recently been used in 5G fronthaul. ) was adopted as a light source for WDM optical communication required in the network. If OPA is implemented using mature polymer optical IC technology, efficient phase control is possible with low power, and deterioration due to nonlinear effects can be excluded even in lidar modules that require strong optical output. . In addition, since polymer tunable lasers and polymer OPA are capable of monolithic integration, it is possible to implement a light source-integrated compact solid-state optical beam scanner.

Various embodiments use a polymer optical waveguide to solve the problem of difficulty in emitting high optical output due to non-linear optical effects in a beam scanner based on silicon optical waveguide OPA and the problem of difficulty in controlling phase distribution due to thermal crosstalk. This is to implement a two-dimensional beam scanner with an integrated light source. Polymer tunable lasers have been commercialized with their performance verified, and can be integrated with polymer optical phased arrays (OPA) on one chip. The two devices were fabricated separately and a two-dimensional beam scanner device was implemented to confirm the feasibility. An OPA device was designed and manufactured using a fluorine-substituted polymer, and its characteristics were confirmed. Initially, the light output scattered due to random phase distribution was beam formed using a phase distribution alignment algorithm, and horizontal beam scanning was performed through a simple form of open-loop phase control. Next, a polymer Bragg grating-based tunable laser was used as a light source and the OPA output light was diffracted on an external blazed grating to implement vertical beam scanning according to wavelength tunability. Finally, the results of a 2D beam scanning experiment using polymer OPA were demonstrated for the first time by simultaneously controlling the tunable laser and the phase modulator array.

The polymer optical waveguide-based light source integrated OPA beam scanner according to various embodiments includes a polymer Bragg grating, a 1ХN power splitter, a phase modulator array, and a beam concentrator ( It consists of optical waveguide elements (concentrator), a broadband SLD (superluminescent diode) element aligned and attached around the chip, a cylindrical lens for vertical beam collimation, and an external grating for spectral dispersion. After passing through the phase modulator and converging at narrow intervals, the beams output from each waveguide form a far-field that converges to one point if there is no phase difference between them. Afterwards, by using a phase modulator to form a tilted phase distribution as shown in (b) of FIG. 1, the beam can be scanned in the horizontal direction. Meanwhile, if the diffraction grating is aligned in the direction in which the output light travels, the diffraction angle changes in the vertical direction according to the output wavelength of the tunable laser, as shown in Figure 1 (c). By performing phase distribution control and wavelength variable control in this way, two-dimensional beam scanning operation can be performed.

According to various embodiments, a polymer OPA device that can be integrated with a wavelength tunable laser is completed using the characteristics of a low-loss fluorine-substituted polymer optical waveguide device, and two-dimensional beam scanning can be realized through phase distribution control and wavelength tunability. Fluorine-substituted polymer optical waveguides can withstand high-output optical power and have low insertion loss, enabling high-output OPA-based lidar devices. By using an external grating, grating diffraction efficiency is increased, optical loss is minimized, and wavelength variation is reduced. Scanning range can be improved. Due to the high efficiency and low thermal crosstalk of the polymer phase modulator, the initial beamforming conditions were not scattered during beam scanning, which stands out as a major advantage over silicon OPA devices. The response speed of the polymer thermo-optical phase modulator can be improved to several tens of us by introducing a high contrast waveguide structure and high thermal conductivity cladding, making fast frame rate beam scanning possible. Lastly, since polymers have transparent properties not only in IR but also in visible wavelengths, it is possible to implement OPA beam scanners that can be used in visible light, as well as glasses-free 3D display bathy metric lidar and neural probes. ), it will be a technology that can be applied to optical tweezers, etc.

Figure 1 shows the structure of a polymer optical waveguide-based light source integrated OPA beam scanner. (a) is a polymer optical waveguide fabricated on a single chip with a Bragg grating, 1xN power splitter, phase modulator array, beam concentrator element, SLD element aligned and attached around the chip, and vertical beam collimation. A 2D beam scanner structure consisting of a cylindrical lens and a diffraction grating is shown. (b) shows that the horizontal output angle can be adjusted by adjusting the phase distribution of the beam output from each waveguide through the polymer phase modulator array. (c) shows that by arranging the output wave to be diffracted on the grating and tuning the reflected wavelength of the polymer Bragg grating, a change in the diffraction angle due to the wavelength change can be obtained.
Figure 2 shows the design of a polymer optical waveguide beam scanner device. (a) shows the photomask layout for manufacturing the 1Х32 splitter, phase modulator array, and beam concentrator that constitute the OPA. (b) shows the cross-sectional structure of a thermo-optical phase modulator with a micro heater located on the top of the optical waveguide. (c) shows the heat distribution analysis simulation calculation results.
Figure 3 shows details for designing the output waveguide spacing of OPA. (a) shows the results of BPM simulation to check optical power crosstalk according to pitch in the waveguide array. (b) shows the far-field distribution for the output of a high contrast optical waveguide array with a pitch of the output waveguide array of 3.5 um. (c) shows the far-field distribution of the output of a low contrast optical waveguide array with a pitch of the output waveguide array of 10 um.
Figure 4 shows the design of scanning angle change using a polymer tunable laser and an external grid. (a) shows a wavelength-tunable laser with an external resonator structure completed by aligning a Bragg reflector and an SLD chip with a polymer optical waveguide. (b) shows that 0.20 nm/mW wavelength tunable efficiency can be obtained as a result of reflection spectrum calculation using Bragg grating and reflection wavelength tunable range design using thermo-optic effects. (c) shows a k-vector diagram to explain the change in the diffraction angle of the grating according to the change in wavelength. (d) shows the results of calculating the input wavelength change range from 1530 nm to 1630 nm and the diffraction angle change range according to various grating periods and input angles. When the incidence angle is 39° and the period is 1 um, the diffraction angle tuning range is about 25° for a 100 nm wavelength change.
Figure 5 shows the contents of a polymer waveguide high power transmission test. (a) shows the results of measuring the output power of the optical waveguide while increasing the input power by +15 dBm using an EDFA light source on a straight polymer optical waveguide, and the output power was seen to be linearly proportional to the input power. (b) shows the results of observation for 160 hours with 1 W optical power input using a high power EDFA light source, and no change in insertion loss was observed.
Figure 6 shows an experiment to check the change in output power according to input power in a 16-channel MZI device. (a) is a CAD drawing for manufacturing a 16-channel MZI device. (b) is a photo of a device whose packaging has been completed. (c) is the result of measuring the interference signal output from the 16-channel MZI by applying power to the 32-channel phase modulator. (d) shows the results of calculating the initial phase values for each channel from (c), and it is confirmed that the initial random phase distribution is shown.
Figure 7 shows confirmation of the characteristics of the polymer OPA device. (a) shows a state in which a polymer element with a pigtailed optical fiber is attached to a package and a cylindrical lens and mirror are aligned. In (b), the uniformity of the optical waveguide output beam can be confirmed from the polymer optical waveguide array output near field pattern. In (c), the far-field pattern passing through the cylindrical lens initially appears scattered in the horizontal direction. In (d), when phase alignment is performed by applying the beamforming algorithm, the main beam gathered at one point in the center and weak side lobes appearing left and right can be seen. In (e) and (f), when an inclined phase signal is applied to the phase modulator array, a beam scanning left and right can be observed.
Figure 8 shows beam scanning characteristics using a polymer tunable laser device and an external grating. (a) shows a wavelength-tunable laser with an external resonator structure completed by connecting a polymer Bragg reflection grating and an external SLD element. (b) shows the results of measuring the output spectrum change that appears when power is applied to the upper heater of the Bragg grid using an optical spectrum analyzer. (c) shows an experimental setup for measuring the diffraction angle change according to the wavelength change after collimating the wavelength-tunable laser output and making it incident at the Littrow angle of the blazed grating. When causing a wavelength conversion of 95 nm using a tunable laser device, a diffraction angle conversion of 14.7° can be obtained.
Figure 9 shows the structure of a 2D beam scanning device based on a polymer optical IC. (a) shows a package structure completed by using a polymer wavelength-tunable laser as a light source and placing a blazed grating on top of the polymer OPA element. For 2D beam scanning measurement, a setup is configured to measure the light passing through the lens through an IR CCD camera. In (b), 2D scanning corresponding to the coordinates of 13 Х 7 points is performed by simultaneously performing wavelength variation and phase control. (c) and (d) show the heart pattern and figure-8 pattern formed by adjusting the signal based on the confirmed input-output relationship.
Figure 10 shows a phase distribution control signal for beam scanning operation. (a) shows the phase slope signal applied to the phase modulator array for scanning after beamforming. (b), (c), and (d) show scanning beam CCD images that appear proportional to the phase slope. Scanning operation is possible while maintaining the beam shape even without phase distribution alignment.
Figure 11 shows the results of beam scanner response speed measurement using a polymer OPA device. (a) shows the scanning speed measurement setup structure. (b) shows the power change measured at the detector during horizontal beam scanning operation through phase distribution control, and a response speed of 7 ms is confirmed when a 0.2 second periodic signal is given. (c) shows the power change measured by the detector during beam scanning operation in the vertical direction through wavelength variable control, and a response speed of 20 ms is confirmed when a signal is given at a 2-second cycle.

Hereinafter, various embodiments of this document are described with reference to the attached drawings.

In general polymer materials, there is an absorption loss due to the vibration overtone of the CH bond in the optical communication wavelength range (1300 ~ 1600 nm). To reduce this, CYTOP, LFR, and CH bonds are used in which the CH bond is replaced by a CF bond. Fluorine-substituted polymers such as fluorinated polyimide have been researched and developed. In this disclosure, ChemOptics' LFR polymer, which has a very high degree of fluorine substitution, was used to manufacture the polymer optical waveguide OPA, and polymers with refractive indices of 1.397 and 1.372 were selected for the optical waveguide core and cladding, respectively. In this case, the size of the core was 1.397 and 1.372, respectively. When 3Х3 um ² , the conditions for a single-mode optical waveguide are satisfied. The photomask layout for manufacturing the 1Х32 splitter, phase modulator array, and beam concentrator that constitute the OPA has the same form as (a) in Figure 2.

A thermo-optical phase modulator for controlling the phase of each channel is manufactured by forming a thin metal film micro-heater on the top of the optical waveguide, as shown in (b) of FIG. 2. When heat is generated in the heater due to resistance heat, the heat is transferred to the core part of the optical waveguide, as shown in Figure 2 (c), causing a change in the refractive index due to the thermo-optic effect. To calculate the efficiency of the polymer phase modulator, heat distribution by the heater was calculated using the finite element method (Optodesigner Software), and Pπ was calculated by reflecting the thermo-optic effect. The thickness of the polymer located below the heater and constituting the optical waveguide, including the lower cladding, core, and upper cladding, is indicated by t1, t2, and t3 as shown in Figure 2 (b), and is set to 9 um, 3 um, and 6 um, respectively. . The thermal conductivity of the polymer used to calculate heat distribution is 0.2 W/mK, the thermo-optic coefficient is 2.5Х10 ^-4 /°C, and the heater width is 10 um. Due to the excellent thermo-optic effect and thermal confinement of polymer materials, the power Pπ for π-phase phase change in a given polymer phase modulator structure was calculated to have a very low value of 2.1 mW.

The pitch of the final output waveguide array determines the side lobe positions and the maximum scanning angle. As the array pitch is reduced, wider range scanning becomes possible, but a narrow pitch causes crosstalk between waveguides. Beam propagation method simulation (using Rsoft's Optodesigner program) was performed to determine the waveguide pitch at the beam concentrating waveguide array, which is the output part of the OPA device. When there are two adjacent straight optical waveguides, the input light was excited in one optical waveguide and then advanced 1 mm before checking the light intensity transmitted to the other optical waveguide (Figure 3(a)). In a polymer optical waveguide where the refractive index of the core and cladding polymer material is 1.397 and 1.372, the gap between the waveguides must be 10 um or more for crosstalk to be less than -10 dB. A method to further reduce the waveguide spacing is to use inorganic nanoparticle dispersed polymers such as ZrO ₂ and TiO ₂ , or sulfur based polymers, which have been actively researched and developed recently, to create optical waveguide cores. There is a way to further increase the refractive index. When the refractive index of the core becomes 1.8, the size of the single-mode optical waveguide is reduced to about 0.8 Х 0.6 um ^2, and it was confirmed that even if the array pitch is reduced to 3.5 um, the crosstalk is maintained below -10 dB.

As the light output from the narrow-pitch waveguide array proceeds, it forms a far-field, which can be obtained through Fourier transform from the optical waveguide array mode distribution. The mode field diameter (MFD) of the low contrast waveguide and the high contrast waveguide is obtained using the mode solver program (Optodesigner software), and the full width at half maximum of the same size is obtained. A Gaussian profile with (full width half maximum; FWHM) was created in an array structure, and then the far-field profile was obtained through Fourier transform calculation. From these results, it was confirmed that in the case of a high contrast waveguide, the side lobes appear 25° away from the main lobe (Figure 3(c)). When calculating the far-field pattern formed by the light output from the high-contrast waveguide array, a side lobe is formed at a 25° position as shown in (b) of FIG. 2. In this experiment, a low contrast polymer waveguide structure with a well-established manufacturing process was used, and the array pitch was manufactured at 10 um, and the side lobes at this time were 9.1 as shown in (b) of Figure 3. It appears in °.

A polymer wavelength tunable laser that can be manufactured by integrating with an OPA device is designed by designing an optical waveguide using the same polymer material used to manufacture OPA, and forming a lattice structure on the upper part of the core as shown in (a) of Figure 4 to achieve C-band (1530). - It is designed to cause Bragg reflection at 1565 nm). Considering the improvement of the reflection spectrum characteristics and the compatibility of the manufacturing process, a 5th order Bragg grating was used. When the grating period is 2.8 um and the etching depth is 350 nm, the transmission matrix calculation results show a reflection of about 20%. appeared, which is an appropriate reflectance as a feedback signal from an external cavity laser. By gradually increasing the power applied to the heater to 200 mW, a change in the reflection spectrum as shown in (b) of FIG. 4 can be obtained, and at this time, the wavelength variable efficiency was found to be 0.20 nm/mW.

Vertical beam scanning can be performed by diffracting a tunable laser output beam through an external grating. At this time, the required period and Littrow angle of the grating can be calculated using a k-vector diagram. As shown in (C) of FIG. 4, the light incident on the blazed grating in the direction of incident angle θi shown in the k-vector diagram is diffracted in the direction θd, and due to the nature of the blazed grating, 0th order reflection occurs. It can be minimized. If the wavelength of the incident light is λ and the grating period is Λ, the diffraction angle can be obtained by the following equation.

Here, k = 2π/λ and Kg = 2π/Λ. The input wavelength change range is set from 1530 nm to 1630 nm, and the diffraction angle change range (Δθd) is calculated according to various grating periods and input angles. The results are shown in Figure 4 (d). When the incidence angle is 39° and the period is 1 um, the diffraction angle tuning range is about 25° for 100 nm wavelength variation. The blaze angle is 39°, and by using a blazed grating with a period of 1 um, vertical beam scanning of as much as 25° is possible for a 100 nm wavelength change.

Based on the design details, a polymer optical waveguide OPA device and a polymer wavelength-tunable laser were manufactured through general semiconductor processes such as spin coating, photo-lithography, and plasma etching. To manufacture a polymer optical waveguide OPA device, a polymer material is spin-coated on a silicon substrate, then a lower cladding layer is formed through UV-curing and thermal curing processes, and a photo-lithography process is performed. A core pattern is formed through and the lower cladding layer is etched using O ₂ plasma to form a channel-shaped groove. Next, a polymer material is coated to fill the groove to form a core cladding layer, and the entire surface is etched again in response to the groove, leaving a channel-shaped core cladding layer. When a polymer material is spin-coated and cured on top, an upper cladding layer is formed, completing the optical waveguide structure. Cr-Au is deposited to 10-100 nm on the upper cladding layer and patterned to form a heater pattern. To manufacture a polymer wavelength-tunable laser, the same optical waveguide structure is manufactured using the same polymer material used in the OPA device. The only difference is that after forming the core pattern, a grid pattern with a period of 2.8 um is formed through a photo-lithography process and etched to a depth of 350 nm using O ₂ plasma. Because polymer optical waveguides have a relatively low refractive index compared to semiconductor materials, a Bragg reflector can be completed by producing a grid with a wide period of about 2.8 um through a photo-lithography process.

To evaluate the basic performance of the fabricated polymer device, distributed feedback (DFB) laser output was coupled to a 2-cm-long linear optical waveguide through a UHNA fiber. The insertion loss was found to be 1.2 dB, which can be divided into coupling loss of 0.3 dB/facet and propagation loss of 0.3 dB/cm. In order to confirm the maximum optical power that the polymer optical waveguide can withstand, the input optical power was amplified to +15 dBm using an erbium-doped fiber amplifier (EDFA) with the optical fibers aligned and attached, but the insertion loss was not found. No change was observed, and no change in insertion loss was observed as a result of observation for 160 hours with 1 W power input using a high power EDFA light source (FIG. 5).

To evaluate the performance of a thermo-optical phase modulator manufactured based on a polymer optical waveguide, a 16-channel Mach-Zender (MZ) interferometer device was fabricated by combining two output units of a 32-channel OPA device as shown in Figure 6 to determine the characteristics. was confirmed. The resistance of the manufactured phase modulator was measured in the range of 46~53Ω, and power was applied to each phase modulator to measure the output interference signal and calculate power efficiency. The Pð of the 16-channel MZ device ranged from 1.8 to 2.0 mW, which was approximately 0.2 mW lower than the design value, and no additional optical loss due to the phase modulator was observed. However, it was confirmed that the initial phase state of the MZ device is not the same. This is due to the slight difference in the waveguide pattern that inevitably occurs during the device manufacturing process and is a phase value that requires correction in the driving stage.

After connecting the optical fiber to the input part of the manufactured polymer OPA device, attach it to the case with the TEC attached, align and fix the cylindrical lens to the output part as shown in (a) of Figure 7, and install a 45° mirror. After making light output in the vertical direction through the beam, the output beam was checked with a CCD. The near-field pattern confirmed by focusing on the cross-section of the optical waveguide shows an even distribution of optical power for each channel, as shown in Figure 7 (b), and the far-field pattern passing through the cylindrical lens When observing the pattern, it appears scattered horizontally as shown in (c) of Figure 7, and when the phase is adjusted through the beamforming algorithm, it converges to one point as shown in (d) of Figure 7. For fast and efficient beam forming, an algorithm applying the rotating element vector (REV) method was developed. The point that appears relatively bright in the far-field pattern that appears in a scattered form is formed by gathering some lights that are in phase among the lights coming from the output optical waveguide array, and the phase of this light is defined as the dominant phase. . By measuring the change in intensity of the light collected while slightly changing the phase of each channel, the relationship between the phase change of each channel and the dominant phase can be identified. By repeating this process for each channel, the current phase status of all channels can be estimated. can do. The beam scanning range is determined by the distance between the centrally located main beam and the side lobes and was measured at 8.9°. The main beam formed at this time was measured to have a loss of 5.2 dB compared to the input optical power. Afterwards, if the power applied to the phase modulator is adjusted by calculating an additional phase value so that the phase distribution of the optical waveguide has a slope, beam scanning can be performed left and right as shown in Figures 7 (e) and (f). Due to the high efficiency and low thermal crosstalk of the polymer phase modulator, the initial beamforming condition did not appear to be scattered during beam scanning, which stands out as a major advantage compared to the silicon OPA device (FIG. 8).

A polymer tunable laser is manufactured by aligning a polymer Bragg grating optical waveguide element and an SLD gain chip as shown in (a) of FIG. 9. The Bragg reflection wavelength is changed by applying a current to the heater manufactured on the Bragg grating, and the result of measuring the change in the resulting output spectrum using an optical spectrum analyzer is shown in Figure 9(b). After collimating the wavelength-tunable laser output, configure the setup as shown in (c) of Figure 9, enter it at the Littrow angle of the blazed grating, and change the diffraction angle according to the wavelength change. Measured. When the wavelength was tunable over 95 nm using Santec's tunable laser equipment, a diffraction angle change of 14.7° was obtained as shown in (d) of Figure 9. The stable wavelength tunable range of the polymer tunable laser is about 1538 nm - 1568 nm, and the resulting diffraction angle change is about 3.9°. Due to the excellent diffraction properties of the blazed grating, the optical power loss of the diffracted beam was maintained within 1 dB throughout the measurement wavelength range.

To complete the two-dimensional beam scanning operation, a polymer wavelength-tunable laser was used as a light source, and a blazed grid was placed on top of the polymer OPA element and aligned as shown in (a) of Figure 10. Manufacturing the laser and OPA in a monolithic integration state was left as the next step of research, and this time, they were connected through optical fiber. A jig printed with a 3D printer was used to input the beam output from the phase modulator array element into the external grid at a precise angle. In order to check the beam scanning operation with a CCD camera, a 5x objective lens was aligned between the beam scanner element and the CCD camera. Beam alignment is performed for each wavelength to obtain initial phase information to complete the look-up table (LUT). By modifying the beamforming phase information along with wavelength conversion, scanning in the vertical direction was possible, and the angle change measured for 30 nm wavelength change was 6.0°. The angle of incidence on the external grid was aligned at 36.6° instead of the Littrow angle of 41°, so the wavelength variation angle was slightly improved from the design value of 3.9°. When horizontal scanning is performed with beamforming completed for a specific wavelength, only the phase modulator input signal needs to be changed to form a phase slope without separate beamforming (FIG. 10). The scanning step was set so that the beams measured by the CCD were far enough apart to be distinguishable. When increasing the phase slope by 15° in the horizontal direction, the scanning angle changed at 0.7° intervals, and when changing the wavelength at 5 nm intervals in the vertical direction, the scanning angle changed at 1.0° increments. As a result, Figure 10 As shown in (b), beam scanning corresponding to the coordinates of 13 x 7 points was possible on the CCD. Input values to form 13 Х 7 points are extracted, and from these, a heart pattern ((c) in Figure 10) and a figure-of-eight pattern ((d) in Figure 10) are created. Formative scanning could be performed.

To check the scanning response time of the polymer optical IC beam scanner, the beam output from the OPA was aligned with a Newport photo detector with an aperture size of 0.3 mm, and then a signal was applied to the polymer phase modulator array. The optical signal that appears when the beam is scanned out of the detector was measured. In order to measure the vertical beam scanning speed through wavelength tunability, the response time of the polymer wavelength tunable laser must be measured. When wavelength conversion occurs by applying a power signal to a heater formed on a Bragg reflection grating, the angle of diffraction from the diffraction grating changes and vertical scanning occurs, allowing changes in the optical signal to be detected. The heater was configured to change the wavelength by 30 nm by applying 50 mW of power at a cycle of 0.2 s, and the optical signal that appeared while scanning the beam out of the detector was measured (FIG. 11). As a result of the measurement, the scanning response speed in the horizontal and vertical directions was found to be 7 ms and 21 ms, respectively.

A two-dimensional beam scanner according to various embodiments includes an optical phased array (OPA) element including a polymer optical waveguide and a Bragg reflector on a portion of the polymer optical waveguide, and an optical phase It is disposed on one side of the array element and includes a diode element (e.g., SLD) that makes light incident on the optical phased array element, and the Bragg reflector reflects the light incident from the diode element, thereby changing the wavelength of the incident light. As the change occurs, the incident light may be diffracted.

According to various embodiments, the two-dimensional beam scanner is disposed on the other side of the optical phased array element, diffracts the beam output from the other side of the optical phased array element, and changes the output angle of the beam in the vertical direction. It may further include grating.

According to various embodiments, the polymer optical waveguide may extend while being split between one input terminal and a plurality of output terminals.

According to various embodiments, the optical phased array element is disposed at the output terminals of the polymer optical waveguide, adjusts the phase distribution of the beams output from the output terminals, and changes the output angle of the beams output in the horizontal direction. It may further include a modulator array (phase modulator array).

According to various embodiments, the optical phased array element is a beam concentrator (beam concentrator) disposed between the phase modulator array and the other side of the optical phased array element, and collecting the beams output from the phase modulator array and outputting them to the other side of the optical phased array element. It may further include a beam concentrator) element.

According to various embodiments, the two-dimensional beam scanner is disposed between the other side of the optical phased array element and the external grid, and disperses the beam output from the other side of the optical phased array element in the horizontal direction and collides in the vertical direction toward the external grid. It may further include a cylindrical lens.

A method of manufacturing a two-dimensional beam scanner according to various embodiments includes manufacturing an optical phased array (OPA) device including a polymer optical waveguide and a Bragg reflector on a portion of the polymer optical waveguide, and on one side of the optical phased array device, It includes the step of attaching a diode element that causes light to enter the optical phased array element, wherein the Bragg reflector reflects the light incident from the diode element, and as a result, the wavelength of the incident light changes and the incident light may be diffracted.

According to various embodiments, a method of manufacturing a two-dimensional beam scanner further includes attaching an external grating to the other side of the optical phased array element, wherein the external grating diffracts the beam output from the other side of the optical phased array element. , This allows the output angle of the output beam to be changed in the vertical direction.

According to various embodiments, manufacturing an optical phased array device includes forming a lower cladding layer made of a polymer material on a substrate, etching the lower cladding layer to form a groove in the lower cladding layer, and forming a groove in the lower cladding layer. forming a core cladding layer made of a polymer material on the layer, etching the core cladding layer to form a core pattern corresponding to the groove, etching the core cladding layer to form a Bragg reflector in the core cladding layer. , forming an upper cladding layer made of a polymer material on the core cladding layer, forming a polymer optical waveguide from the core pattern, and patterning the upper cladding layer to form a heater in the upper cladding layer. .

According to various embodiments, the polymer optical waveguide may extend while being split between one input terminal and a plurality of output terminals.

According to various embodiments, the optical phased array element is disposed at the output terminals of the polymer optical waveguide, adjusts the phase distribution of the beams output from the output terminals, and changes the output angle of the beams output in the horizontal direction. It may further include a modulator array.

According to various embodiments, the optical phased array element is a beam concentrator element that is disposed between the phase modulator array and the other side of the optical phased array element, and collects beams output from the phase modulator array and outputs them to the other side of the optical phased array element. It may further include.

According to various embodiments, attaching the external grating includes attaching a cylindrical lens to the other side of the optical phased array element, and attaching the external grating to the cylindrical lens, wherein the cylindrical lens is attached to the optical phased array element. The beam output from the other side of the device can be dispersed in the horizontal direction and collimated in the vertical direction toward the external grid.

The various embodiments of this document and the terms used herein are not intended to limit the technology described in this document to a specific embodiment, and should be understood to include various changes, equivalents, and/or replacements of the embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar components. Singular expressions may include plural expressions, unless the context clearly indicates otherwise. In this document, expressions such as “A or B”, “at least one of A and/or B”, “A, B or C” or “at least one of A, B and/or C” refer to all of the items listed together. Possible combinations may be included. Expressions such as "first", "second", "first" or "second" can modify the corresponding components regardless of order or importance, and are only used to distinguish one component from another. The components are not limited. When a component (e.g. a first) component is said to be "connected (functionally or communicatively)" or "connected" to another (e.g. a second) component, it means that the component is connected to the other component. It may be connected directly to a component or may be connected through another component (e.g., a third component).

According to various embodiments, each of the described components may include a single or plural entity. According to various embodiments, one or more of the components or steps described above may be omitted, or one or more other components or steps may be added. Alternatively or additionally, multiple components may be integrated into one component. In this case, the integrated component may perform one or more functions of each component of the plurality of components identically or similarly to those performed by the corresponding component of the plurality of components prior to integration. According to various embodiments, the steps may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the steps may be executed in a different order, omitted, or one or more other steps may be added. .

Claims (5)

In a two-dimensional beam scanner,
optical phased array (OPA) device;
a diode element disposed on one side of the optical phased array element and allowing light to enter the optical phased array element; and
An external grid disposed on the other side of the optical phased array element and diffracting the beam output from the other side of the optical phased array element, thereby changing the output angle of the output beam in the vertical direction.
Including,
The optical phased array element,
Board;
A polymer optical waveguide extending while being split between one input terminal and a plurality of output terminals on the substrate;
A Bragg reflector that reflects the incident light from the diode element on a portion of the polymer optical waveguide on the substrate, thereby diffracting the incident light as the wavelength of the incident light changes;
a phase modulator array disposed at the output terminals of the polymer optical waveguide on the substrate and adjusting the phase distribution of the beams output from the output terminals, thereby changing the output angle of the beams output in the horizontal direction; and
A beam concentrator element disposed between the phase modulator array and the other side of the optical phased array element on the substrate, and collecting beams output from the phase modulator array and outputting them to the other side of the optical phased array element.
Including,
The optical phased array element,
Forming a lower cladding layer made of a polymer material on the substrate,
Etching the lower cladding layer to form a groove in the lower cladding layer,
Forming a core cladding layer made of a polymer material on the lower cladding layer,
Etching the core cladding layer to form a core pattern corresponding to the groove,
Etching the core cladding layer to form the Bragg reflector in the core cladding layer,
Forming an upper cladding layer made of a polymer material on the core cladding layer to form the polymer optical waveguide from the core pattern,
Patterning the upper cladding layer to form a heater in the upper cladding layer.
manufactured including,
The two-dimensional beam scanner,
It is disposed across one corner of the substrate between the other side of the optical phased array element and the external grid, has a cylindrical shape surrounding an axis parallel to the corner, and directs the beam output from the other side of the optical phased array element in a horizontal direction. A cylindrical lens that collimates in a vertical direction toward the external grid while dispersing
Containing more,
Two-dimensional beam scanner.
delete In the method of manufacturing a two-dimensional beam scanner,
manufacturing an optical phased array (OPA) device;
Attaching a diode element that makes light incident on the optical phased array element to one side of the optical phased array element;
attaching a cylindrical lens to the other side of the optical phased array element; and
Attaching an external grid to the cylindrical lens.
Including,
The external grid is,
Diffracts the beam output from the other side of the optical phased array element, thereby changing the output angle of the output beam in the vertical direction,
The optical phased array element,
Board;
A polymer optical waveguide extending while being split between one input terminal and a plurality of output terminals on the substrate;
A Bragg reflector that reflects the incident light from the diode element on a portion of the polymer optical waveguide on the substrate, thereby diffracting the incident light as the wavelength of the incident light changes;
a phase modulator array disposed at the output terminals of the polymer optical waveguide on the substrate and adjusting the phase distribution of the beams output from the output terminals, thereby changing the output angle of the beams output in the horizontal direction; and
A beam concentrator element disposed between the phase modulator array and the other side of the optical phased array element on the substrate, and collecting beams output from the phase modulator array and outputting them to the other side of the optical phased array element.
Including,
The step of manufacturing the optical phased array element is,
forming a lower cladding layer made of a polymer material over the substrate;
etching the lower cladding layer to form a groove in the lower cladding layer;
forming a core cladding layer made of a polymer material on the lower cladding layer;
etching the core cladding layer to form a core pattern corresponding to the groove;
forming the Bragg reflector in the core cladding layer by etching the core cladding layer;
forming an upper cladding layer made of a polymer material on the core cladding layer, thereby forming the polymer optical waveguide from the core pattern; and
Patterning the upper cladding layer to form a heater in the upper cladding layer.
Including,
The cylindrical lens is,
It is disposed across one corner of the substrate between the other side of the optical phased array element and the external grid, has a cylindrical shape surrounding an axis parallel to the corner, and directs the beam output from the other side of the optical phased array element in a horizontal direction. A method of collimating in a vertical direction toward the external grid while dispersing. delete delete