KR20050015645A - Apparatus for Production of High Polymer Plane Optical Waveguide using Laser Patterning - Google Patents

Abstract

PURPOSE: An apparatus of fabricating a polymer plane type optical waveguide using a laser patterning method is provided to simplify a process of an optical waveguide by changing a refractive index of a high polymer based on irradiating directly laser beams along a designed shape without a mask or an additional process. CONSTITUTION: A laser source(3) is used for outputting laser beams. An AOM(acoustic optic modulator)(4) is used for adjusting and modulating the outputs of the laser beams. A lens part(6) is used for removing noise from the output beams of the AMO and securing parallel beams. A reflector(7) is used for changing an optical path of the output beams from the lens part. A beam splitter(8) is used for splitting the output beams of the reflector. A CCD(charge coupled device) camera(9) is used for identifying a focus before a patterning process. A light receiving element(11) is used for maintaining constantly optical power. A computer(12) is used for controlling the AMO and a transferring stage and driving a PZT(piezoelectric transducer)(14) according to a power value of the light receiving element. The PZT(14) is used for controlling fully a position of a zoom object lens according to a variation of the power value.

Description

Apparatus for Production of High Polymer Plane Optical Waveguide using Laser Patterning}

The present invention is to produce a planar optical waveguide device using a polymer, a polymer using a laser drawing technique to realize a precise optical waveguide by forming a core by changing the refractive index by directly irradiating a laser beam on a polymer substrate without a mask or complicated additional process The present invention relates to a planar optical waveguide fabrication apparatus, and more particularly, to a laser direct drawing for forming a core having a desired structure by changing a refractive index by directly irradiating a laser beam onto a polymer substrate without a mask for photolithography or an additional process. It is a device for manufacturing a planar optical waveguide, and in order to construct a laser direct drawing device, it is possible to maintain the laser beam from the laser light source as parallel light for the production of precise and reproducible optical waveguides, According to the focus of the laser beam Relates to an apparatus for manufacturing the optical waveguide provided by the auto-focus function to compensate the height difference according to the section, the curvature of the surface of the substrate and to control the spot size (Spot Size) of the beam, the imaging process.

In addition, the present invention can form a multi-mode optical waveguide by overlapping and drawing several times not only a single mode optical waveguide, but also by moving the focus and adjusting the focal length during drawing, and also having various structures such as a curved optical waveguide as well as a curved optical waveguide Planar optical waveguide device provides simple and precise function without using mask.

Recently, optical communication system technology development using planar optical devices such as wavelength division multiplex (WDM) system has been developed according to the demand for high speed and large capacity of optical communication system. Although it has been manufactured using technology, recently, a planar optical waveguide device research using a polymer has been made due to the demand for low cost.

Until now, optical devices and components necessary for high-capacity optical communication, information recording, and ultra-high speed of information processing have been developed based on semiconductor materials and inorganic silica-based materials, but recently, due to the advantages of low cost and simple processing, Interest is growing.

As a conventional technique, a method of fabricating a planar optical waveguide using a polymer has been mainly used, but a new method such as a laser direct drawing method or a hot embossing technique has recently been proposed.

The exposure method using a mask is a method of manufacturing a mask designed according to the optical waveguide structure and closely attaching it to a substrate, and forming an optical waveguide by ultraviolet (UV) exposure. Hot embossing is required by electroplating or silicon substrate etching. The opposite shape of the optical waveguide is made and it is used as a mold and printed on the polymer substrate. These methods have a problem that the process is complicated, such as the need to separately manufacture the mask, or separately formed the waveguide core after the embossing in a post-process. This will be described in more detail as follows.

Optical waveguide fabrication using polymer materials is carried out in various ways, and common processing techniques include photolithography, hot embossing, direct UV patterning, and laser direct drawing.

The photolithography process involves coating a cladding material on a substrate, baking it, coating a core material, applying a photoresist, an exposure process using a photomask, developing, etching, and the like. It goes through a complicated process.

In addition, the hot embossing process molds the structure of the core portion using a mold master to the lower clad material, injects the core material into the formed structure, then covers the upper cladding, and the ultraviolet light for curing the core material and adhering the upper clad. Investigate

The UV direct drawing method coats the UV curable polymer with the core layer after forming the lower clad on the planar substrate. In addition, after exposing ultraviolet light using a photomask, a core pattern is formed using a polymer developer, and then coated with an upper clad material.

In the optical waveguide fabrication method by laser direct drawing, a laser beam is focused on a photoreactive polymer material, and a drawing process is performed. The drawn pattern has a relatively high refractive index, thereby forming an optical waveguide.

Laser direct drawing technology is based on laser micromachining technology.

1 is a diagram illustrating an embodiment of a general laser direct drawing method, in which a laser beam passes through a light source, a filter, and a shutter, and irradiates a laser beam focused on a substrate through an objective lens to form an optical waveguide. .

The light generated by the laser 101 passes through a filter (Tunable Neutral Density Filter) 103 and a shutter 104 and is irradiated onto the substrate 112 through the microscope 110 and the objective lens 111.

The clad material is coated on the substrate 112 and the core layer is coated. The optical waveguide can be manufactured by a simple process of focusing a laser beam on a core layer to draw a desired pattern.

The pattern drawn by the laser has a higher refractive index than the non-drawn adjacent area, thereby forming an optical waveguide based on the total reflection principle.

The laser direct drawing process is a simple process that does not require a photo mask, and has advantages of shortening process time, low cost, and large area application.

However, the implementation of the optical waveguide by the conventional laser direct drawing using the Gaussian beam has a problem in that it is not easy to implement the cross-sectional shape of the optical waveguide clearly due to the nature of the light, and it is difficult to precisely implement the optical waveguide. In addition, in the case of a large waveguide such as a multimode optical waveguide, when the laser direct drawing is applied, the beam is diffused due to the nature of the light, so that it is difficult to accurately implement the rectangular optical waveguide required by one direct drawing. In addition, it is difficult to control the fine focus according to the required optical waveguide width and maintain constant focus, so that it is difficult to implement a precise optical waveguide.

The present invention has been proposed to solve the above problems, a simple process of directly irradiating a laser beam to the polymer substrate without a mask or additional additional process by laser direct drawing to change the refractive index of the polymer easily and precise optical waveguide It is an object of the present invention to provide a polymer planar optical waveguide fabrication apparatus using a laser drawing technique that can be produced.

The apparatus of the present invention for achieving the above object is a polymer planar optical waveguide manufacturing apparatus using a laser drawing technique having a photoreactive polymer substrate, a transfer stage for moving the photoreactive polymer substrate, and a zoom objective lens having a zoom function A laser light source for emitting constant parallel light; Modulation means for adjusting and modulating the light output of the laser beam output from the laser light source; A lens unit for removing noise of the beam output from the modulation means and ensuring parallel light; Reflecting means for changing a path of a beam output from the lens unit; Beam separating means for separating the beam output from the reflecting means; A camera for checking focus before the drawing process by forming an interference fringe using a path difference of the laser beam; A light receiving element for detecting and maintaining a constant optical power; Computing means for controlling the modulation means and the transfer stage and driving piezoelectric conversion means by receiving a power value of the light receiving element; And the piezoelectric conversion means for adjusting and finely adjusting the position of the zoom objective lens in accordance with the change of the power value.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram of an embodiment of a polymer planar optical waveguide fabrication apparatus using a laser drawing technique according to the present invention.

As shown in FIG. 2, the apparatus for fabricating a polymer planar optical waveguide according to the present invention includes a laser light source 3 emitting a laser beam, and controlling and modulating the light output of the laser beam output from the laser light source 3. Acousto-optic modulator (AOM) (4), lens unit (5, 6) for removing noise of the beam output from the acousto-optic modulator (AOM) (4) and to ensure parallel light, the lens unit (5, 6) Check the focus before the drawing process by reflector (7) for changing the path of the beam output from the beam), Beam Splitter (8) for separating the beam, and interference fringe formation using the path difference of the laser beam A CCD (Charge Coupled Device) camera 9 for controlling the light receiving element 11 for detecting and maintaining a constant optical power, and controlling the AO 4 and the micro stage 13 to receive the light. For driving the piezoelectric transducer (PZT) 14 by receiving the power value of the element 11 The computer 12 includes the piezoelectric transducer (PZT) 14 for instantaneously fine-tuning the position of the zoom objective lens 16 in accordance with the change in the power value.

In the polymer planar optical waveguide fabrication apparatus according to the present invention, two horizontal rails (2) are mounted on two posts (1), and a laser beam emitted from the laser light source (3) to ensure stable and constant parallel light. Through the Acoustic Optic Modulator (AOM) (4), and through the two lenses (6) with a pin hole (5) between them to reduce or enlarge the beam to secure noise and parallel light Has a structure to do In addition, there are a plurality of reflecting mirrors 7 for changing the path of the formed laser beam, two beam splitters 8 are present on the vertical axis where the drawing takes place, and through the formation of an interference fringe using the path difference of the laser beam. By using the CCD camera 9, the focus is checked before the drawing process, or the optical power detected by the light receiving element 11 is kept constant to perform the function of automatically maintaining the focal length during the drawing process.

In the drawing of the designed optical waveguide shape, the laser beam is irradiated while the micro stage 13 moves on the X-axis and the Y-axis by the computer 12, so that the optical waveguide is made.

Acoustic optical modulator (AOM) 4 and the micro stage 13 are driven and controlled by a computer 12, and the power value of the light receiving element 11 for auto focus is input to the computer 12. The piezoelectric transducer (PZT) 14 is driven and controlled.

FIG. 3 is a detailed configuration diagram of an embodiment of a lens unit for forming parallel light of a polymer planar optical waveguide fabrication apparatus according to the present invention, which is for maintaining parallelism of the laser beam emitted from the laser light source 3.

The parallel beam is necessary because the power distribution of the laser beam is symmetrical and the interference fringe is easily formed by misalignment when focusing the laser beam on the polymer substrate 15 in the preparation step of the drawing process.

The configuration is made by injecting the beam through the laser light source (3) and the acoustic optical modulator (AOM) (4) to the lens (6) to reduce the size of the beam through the fine pin hole (5) to remove noise Then, it passes through the lens 6 of the opposite shape and expands to the size of the beam to produce the balanced light.

The lens 6 is equipped with a micrometer to enable fine positioning.

4 is an exemplary explanatory diagram of a method for confirming a focus for fabricating a polymer planar optical waveguide according to the present invention, and confirming that a focus of a laser beam of a required size is formed on the polymer substrate 15. It shows an example configured for.

In the path where the laser beam reaches the polymer substrate 15, the power of the laser beam incident by the beam separator 8 is separated and transmitted in two paths of 50%, one of which reaches the polymer substrate 15. The reflected beam is reflected by the reflection mirror 7 and the reflected beam 7 is combined with the CCD 9.

If the focus is not correct, interference fringes are generated by the path difference between the two laser beams.

The interference fringe is confirmed by the monitor through the CCD camera 9, and the spot size of the beam required by the zoom objective lens 16 which can adjust the magnification can be adjusted and confirmed. The micrometer attached to the objective lens 16 is finely adjusted.

FIG. 5 is an explanatory view of another embodiment of a method for maintaining a constant focus during a process for fabricating a polymer planar optical waveguide according to the present invention, wherein a height difference due to bending of the surface of the polymer substrate 15 during a laser direct drawing process is shown. It shows the method to implement the auto focus function to correct the error.

The beam reflected from the surface of the polymer substrate 15 used for focusing in the state of maintaining the focus before the drawing process is detected by the light receiving element (PD) 18 through the beam separator 8, and the The maximum power is checked using the pin hole 19 to finely adjust the power, and based on this value, the power change according to the stage movement is continuously detected during the drawing process and the difference is detected in the piezoelectric transducer (PZT) 20. By feeding back to the focal length of the zoom objective lens 16 to adjust the instantaneous power to maintain a constant focal length to operate at all times.

FIG. 6 is an exemplary explanatory diagram showing a laser beam of a polymer planar optical waveguide fabrication apparatus according to the present invention, and shows a shape of a laser donut type beam mode (TEM ₀₁ mode) of a laser light source to be used.

The refractive index distribution of the optical waveguide core is determined by the total amount of energy received by the photoreactive polymer material at a specific point, and can be obtained by integrating the intensity distribution of the beam used for drawing with respect to the direction of the beam travel.

7 is an exemplary explanatory diagram showing an exposure amount in a waveguide width direction according to the type of laser beam mode according to the present invention.

It is a graph comparing the energy distribution received by the optical waveguide by the single Gaussian beam and the donut-shaped beam by simulation.

Since the refractive index change of the photoreactive polymer shows a linear change before reaching the saturation region of the refractive index change, the energy distribution received by the optical waveguide has the same shape as the change of the refractive index. Therefore, the boundary of the optical waveguide core can be realized in a stepped shape with a donut-shaped beam.

Looking at the specific simulation conditions, the single Gaussian graph shows the refractive index distribution of the optical waveguide formed by the single Gaussian beam having a diameter of 6 μm, and the graph showing the TEM ₀₁ mode is used to improve the optical waveguide side refractive index distribution by the conventional technique. For example, a case of using a donut shaped beam (TEM ₀₁ mode) is illustrated.

As can be seen from the graph, it can be seen that the refractive index distribution of the optical waveguide generated by the donut-shaped beam forms an excellent step-shaped refractive index distribution compared to a single Gaussian, and the beam size and interval are appropriately needed. I can regulate it.

FIG. 8 is a diagram illustrating an embodiment of a method for implementing a multimode optical waveguide using the polymer planar optical waveguide fabrication apparatus according to the present invention, wherein the position and focal length of the beam several times according to the waveguide width and depth are piezoelectric transducers (PZT). It is possible to implement a multi-mode optical waveguide having an improved refractive index distribution than the optical waveguide drawn at one time by drawing by driving / controlling with the computer 12 using the 14 and the micro stage 13.

In order to achieve the above technical problem, the present invention includes coating a clad material on a substrate, coating a photoreactive polymer as a core layer material on the clad material, and a direct drawing step of forming an optical waveguide using a laser beam. To provide a precise and reproducible optical waveguide, the present invention provides a method for manufacturing a polymer planar optical waveguide including a function of adjusting spot size of a laser beam and automatically maintaining focus during a process.

That is, the clad material is coated on the flat substrate to fabricate the optical waveguide, and the photoreactive polymer is coated on the clad material as the core layer material by the height of the required optical waveguide cross section. Then, the laser beam is focused on the core layer material for laser direct drawing, and the beam size is adjusted by the required waveguide size.

Then, the optical waveguide pattern is drawn by moving the stage on which the polymer substrate is placed. The pattern exposed to the laser beam has a higher refractive index than the unexposed material and functions as an optical waveguide by the principle of total reflection.

On the other hand, the present invention uses a laser light source of the TEM ₀₁ mode to improve the lateral refractive index distribution of the core of the conventional laser direct drawing device, and in the construction of the drawing device in the laser light source for producing a precise, reproducible optical waveguide The laser beam can be maintained as parallel light, and the optical system that can zoom in accordance with the required optical waveguide width can be used to adjust the focus of the laser beam and to control the spot size of the laser beam. In addition, it provides an auto focus function that corrects the height difference caused by the bending of the substrate surface during the drawing process.

In addition, the laser according to the present invention improves the refractive index distribution by adjusting and overlapping the focal length several times in drawing a multimode optical waveguide of 50 μm or more by adjusting the spot size of an appropriate beam using the apparatus according to the present invention. Provide direct writing techniques.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention eliminates the need for a mask or exposure process as in a lithography process and eliminates the need for a separate post process to form a core as in a hot embossing technique. In addition, since the waveguide is formed by directly irradiating the laser beam along the designed shape, the process can be simplified, and any complex optical waveguide shape can be economically realized in a short time. Accordingly, there is an effect that simple and precise manufacturing of planar optical waveguide devices having various and complex structures, such as single-mode, multi-mode linear and curved optical waveguides, as well as wavelength division multiplexing (WDM).

1 is a diagram illustrating an embodiment of a general laser direct drawing method.

Figure 2 is a configuration diagram of an embodiment of a polymer planar optical waveguide fabrication apparatus using a laser drawing technique according to the present invention.

Figure 3 is a detailed configuration diagram of an embodiment showing a lens unit for forming parallel light of the polymer planar optical waveguide fabrication apparatus according to the present invention.

Figure 4 is an embodiment explanatory diagram for a method for confirming the focus for manufacturing a polymer planar optical waveguide according to the present invention.

5 is a diagram illustrating another embodiment of a method for maintaining a constant focus during a process for fabricating a polymer planar optical waveguide according to the present invention.

Figure 6 is an illustrative view showing a laser beam of the polymer planar optical waveguide fabrication apparatus according to the present invention.

7 is an explanatory diagram showing an exposure amount in a waveguide width direction according to the type of laser beam mode according to the present invention;

8 is a diagram illustrating an embodiment of a method for implementing a multimode optical waveguide using the polymer planar optical waveguide fabrication apparatus according to the present invention.

* Explanation of symbols for the main parts of the drawings

1: Post 2: Rail

3: laser light source 4: acoustic optical modulator (AOM)

5: pinhole 6: lens

7: reflector 8: beam splitter

9: CCD camera 11: light receiving element

12 computer 13: micro stage

14: piezoelectric transducer (PZT) 15: polymer substrate

16: zoom objective lens

Claims (7)

In the apparatus for producing a polymer planar optical waveguide using a laser drawing technique having a photoreactive polymer substrate, a transfer stage for moving the photoreactive polymer substrate, and a zoom objective lens having a zoom function, A laser light source for emitting a laser beam; Modulation means for adjusting and modulating the light output of the laser beam output from the laser light source; A lens unit for removing noise of the beam output from the modulation means and ensuring parallel light; Reflecting means for changing a path of a beam output from the lens unit; Beam separating means for separating the beam output from the reflecting means; A camera for checking focus before the drawing process by forming an interference fringe using a path difference of the laser beam; A light receiving element for detecting and maintaining a constant optical power; Computing means for controlling the modulation means and the transfer stage and driving piezoelectric conversion means by receiving a power value of the light receiving element; And The piezoelectric conversion means for minutely adjusting the position of the zoom objective lens according to the change of the power value Optical waveguide fabrication apparatus comprising a. The method of claim 1, The laser beam of the laser light source, Substantially, the optical waveguide fabrication apparatus, characterized in that the TEM ₀₁ mode. The method of claim 1, The lens unit, The beam emitted through the laser light source and the modulating means is incident to the first lens to reduce the size of the beam, pass it through a fine pin hole to remove noise, and then pass the beam to the second lens of the opposite shape to equilibrate the beam. An optical waveguide fabrication apparatus, characterized in that made of light. The method of claim 1, The zoom objective lens, The optical waveguide fabrication apparatus, characterized in that the predetermined size of the laser beam focused on the surface of the polymer substrate can be finely adjusted according to the width of the optical waveguide. The method of claim 1, The beam separation means, The incident laser beam is separated into two beams, and the focus and size of the laser beam can be confirmed by checking the interference fringe on the screen of the computing means by using the path difference of these beams combined by reflection again. Optical waveguide fabrication device. The method of claim 1, The light receiving element, Optical waveguide fabrication apparatus, characterized in that it is possible to monitor the optical power reflected from the surface of the substrate by detecting the laser beam reflected from the substrate, without using a separate additional light source to correct the height difference due to unevenness of the substrate surface . The method according to any one of claims 1 to 6, The computing means, The optical waveguide manufacturing apparatus characterized in that the optical power measured by the light-receiving element is automatically maintained constant, and the piezoelectric conversion means is controlled to secure a constant focal length during the process and automatically maintain the focus.