JP4880901B2 - Optical recording apparatus using optical waveguide array - Google Patents

Description

  The present invention relates to an optical recording apparatus using an optical waveguide array that performs optical recording by modulating and scanning a plurality of laser beams emitted from an optical waveguide array having a wavelength of 420 nm or less onto a photosensitive material.

  A technique for modulating and scanning a plurality of laser beams on a photosensitive material to perform optical recording has been put to practical use in laser printers. A laser printer using a multi-beam can reduce the rotation speed and light modulation speed of the rotary polygon mirror by the number of multi-beams, so that the laser printer can be increased in speed and definition.

  FIG. 1 shows a laser printer optical system using an optical fiber array as a multi-beam generating element. Each of the multi-beams emitted from the optical fiber array 8 is converted into parallel light by the collimator lens 7, then expanded by beam expanders 5 and 6, and scanned on the photosensitive drum 1 by the polygon mirror 3.

  A light spot array is formed on the photosensitive drum 1. As shown in FIG. 3, since the interval between the light spots is usually larger than the size of the light spot, the arrangement direction of the light spot rows is inclined with respect to the scanning direction, and the optical scanning lines are continuous. Make sure that The cylindrical lens 4 disposed in front of the polygon mirror 3 has a function of suppressing the position fluctuation of the optical scanning line caused by the precession generated while the polygon mirror 3 is rotating.

  FIG. 2 shows a cross section of the optical fiber array section. Each of the optical fibers 9 is accurately brought into close contact with the V-groove of the silicon crystal 12, pressed by the glass plate 13, and fixed by the adhesive 14. If the optical fiber core portion 92 exists at the center of the optical fiber 9, the beams emitted from the optical fiber array 8 are accurately arranged on a straight line.

JP 2002-299746 A

  Actually, since the optical fiber has a structural error, the beams emitted from the optical fiber array are not accurately arranged on a straight line and have an arrangement error. This is one of the reasons why high-quality printing cannot be obtained. In order to solve this problem, it is necessary to use an optical waveguide array as a multi-beam generating element. An optical waveguide array is capable of manufacturing a large number of core portions at a narrow pitch with a high precision array. By using a plurality of laser beams emitted from the optical waveguide array, high speed, high definition, and high quality are achieved. Printing is possible.

Usually, an optical waveguide that guides a laser beam having a short wavelength is changed in quality when manufactured with a resin-based material. Therefore, the optical waveguide is manufactured with a glass material such as SiO ₂ . The core part is manufactured so as to contain a small amount of GeO ₂ , TiO _2, etc., and have a relative refractive index difference of about 0.1 to 0.7%. However, as the wavelength becomes shorter, scattering due to Rayleigh scattering or the like increases, and the propagation loss of the optical waveguide increases. In particular, when a material such as GeO ₂ or TiO ₂ becomes a short-wavelength laser beam having a wavelength of 420 nm or less, the scattering coefficient increases rapidly, and the light utilization efficiency of the optical waveguide decreases.

The present invention relates to an optical recording apparatus that performs optical recording by modulating and scanning a plurality of laser beams emitted from an optical waveguide array having a wavelength of 420 nm or less onto a photosensitive material. The optical waveguide array includes an undercladding layer and an undercladding layer. a core portion located in consists overcladding layer covering the said core upper surface and the core side surface, said core portion is viewed contains the Al ₂ O ₃ to SiO _2, and the core diameter or greater 2μm Features.

According to the present invention, in an optical recording apparatus that performs optical recording by modulating and scanning a plurality of laser beams emitted from an optical waveguide array having a wavelength of 420 nm or less onto a photosensitive material, the optical waveguide array includes an underclad layer and the underclad layer. By using an over clad layer that covers the core portion on the top, the upper surface of the core portion, and the side surface of the core portion, and using the material of the core portion containing Al ₂ O ₃ in SiO ₂ , a wavelength of 420 nm Even when the following short-wavelength laser light is used, an optical recording apparatus using an optical waveguide array with high light utilization efficiency can be manufactured.

  In the optical recording apparatus using the optical waveguide array, the laser light emitted from each semiconductor laser 11 is incident on each optical fiber 9 of the optical fiber array as shown in FIG. The semiconductor laser beam is guided to the optical waveguide array by connecting to the incident end face of the optical waveguide array. Since the clad diameter of the optical fiber is usually 125 μm, the pitch interval of the optical fiber array is about 150 μm. Usually, since the distance between the light spots is larger than the size of the light spot, as shown in FIG. 3, the arrangement direction of the light spot rows is inclined with respect to the scanning direction. Try to be continuous.

  The larger the interval between the light spots, the larger the angle θ, and the larger the angle θ, the narrower the angle error tolerance, and the deterioration of the print quality due to the angle error increases. Therefore, a plurality of laser beams guided to the optical waveguide array at a pitch interval of 150 μm by the optical fiber array are pitch-converted by the optical waveguide array as shown in FIG. 5, and are narrowed to about 25 μm. Accordingly, the angle θ can be reduced, and the influence on the print quality due to the angle error can be reduced.

  Since the optical waveguide array needs to be in single mode, it is necessary to reduce the core diameter if the relative refractive index difference of the core portion is increased, and the core diameter can be increased if the relative refractive index difference of the core portion is decreased. It becomes. If the relative refractive index difference is reduced and the core diameter is increased, the allowable axis deviation when guiding the laser beam to the optical waveguide array core portion increases, but the bending loss increases, the relative refractive index difference is increased and the core diameter is reduced. Then, the bending loss is reduced, but the allowable axial deviation is reduced. From these relationships, the optimum relative refractive index difference and core diameter of the core part are determined.

  When calculated by the Markutley method, when a laser beam having a wavelength of 420 nm is used, when the core diameter is 2 μm, a single mode is obtained when the relative refractive index difference is 0.26% or less. When the core diameter is 2.5 μm, a single mode is obtained when the relative refractive index difference is 0.17% or less. When the core diameter is 2 μm or less, the allowable amount of axial deviation when the laser beam is guided to the incident end face of the optical waveguide array becomes narrow, and it is difficult to manufacture. The relative refractive index difference for achieving a single mode with a core diameter of 2 μm or more becomes smaller as the wavelength becomes shorter.

The relative refractive index difference of the deposited film was measured when EB deposition of a deposition material containing 5 w% Al ₂ O ₃ in SiO ₂ on quartz glass. The relative refractive index difference of the deposited film was about 0.4% although it changed depending on the deposition conditions. From this, the material of the optical waveguide array core part for guiding laser light having a wavelength of 420 nm or less is optimally designed for both the core diameter and the relative refractive index difference when a material containing 5% by weight or less of Al ₂ O _{3 in} SiO ₂ is used. It can be seen that an optical waveguide array can be fabricated.

The manufacturing process of the optical waveguide array will be described with reference to FIG. First, a material containing Al ₂ O ₃ in SiO ₂ is deposited on the quartz glass wafer 19 or a silicon wafer 19 with a thermal oxide film having a thickness of 10 μm or more by the EB vapor deposition method to form the waveguide layer 22. Next, a chromium film 23 is sputter-deposited on the waveguide layer. Then, a photoresist 23 is spin-coated on the chromium film, pre-baked, exposed, and developed to form a waveguide pattern of the photoresist on the chromium film.

  Thereafter, post-baking is performed, wet etching of the chromium film is performed, and then the photoresist is peeled off. As a result, a chromium film waveguide pattern is formed on the waveguide layer. Thereafter, the core pattern of the optical waveguide array is formed on a quartz glass wafer or a silicon wafer with a thermal oxide film through processes of dry etching and wet etching of a chromium film.

Next, SiO ₂ is formed as the over clad layer 21 by CVD, flame deposition, sputtering, or the like. Thereafter, the incident / exit end face is polished.

  A method of guiding a plurality of laser beams to the optical waveguide array will be described with reference to FIG. Laser light emitted from each semiconductor laser is condensed on the incident end face of each optical fiber core by the lens 26. The output end face of the optical fiber array is connected to the incident end face of the optical waveguide array so that the coupling efficiency to the optical waveguide array is maximized. For connection fixing, fixing using a UV curable resin, fixing using laser welding, or the like is used.

  Next, the optical system of the optical recording apparatus using the optical waveguide array will be described with reference to FIG. Each of the multi-beams emitted from the optical waveguide array 15 is converted into parallel light by the collimator lens 7, then expanded by beam expanders 5 and 6, and scanned on the photosensitive drum 1 by the polygon mirror 3. A light spot array is formed on the photosensitive drum 1.

  Usually, since the distance between the light spots is larger than the size of the light spot, the arrangement direction of the light spot rows is inclined with respect to the scanning direction so that the light scanning lines are continuous. To do. The cylindrical lens 4 disposed in front of the polygon mirror 3 has a function of suppressing the position fluctuation of the optical scanning line caused by the precession generated while the polygon mirror 3 is rotating.

  An embodiment for guiding a plurality of laser beams to the optical waveguide array will be described with reference to FIG. The exit end face of each semiconductor laser 11 is brought close to the entrance end face of each core part of the optical waveguide array, and the laser light emitted from the semiconductor laser is guided directly to each core part of the optical waveguide array.

  An embodiment in which a plurality of laser beams are guided to the optical waveguide array will be described with reference to FIG. Laser light emitted from each semiconductor laser is condensed by the lens 25 on each core portion incident end face of the optical waveguide array and guided to each core portion of the optical waveguide array.

  An optical recording apparatus that performs optical recording by modulating and scanning a plurality of laser beams emitted from an optical waveguide array having a wavelength of 420 nm or less onto a photosensitive material can be used in a high-speed, high-definition laser printer.

It is explanatory drawing which showed the optical system of the laser printer which carries out the modulation scanning of the several laser beam radiate | emitted from an optical fiber array on a photosensitive material, and carries out optical recording. It is explanatory drawing which showed the cross section of the optical fiber array. It is explanatory drawing which showed the scanning method which scans a several laser beam on a photosensitive material. It is explanatory drawing which showed the optical system of the laser printer which carries out the modulation scanning of the some laser beam radiate | emitted from an optical waveguide array on a photosensitive material, and carries out optical recording. It is explanatory drawing which showed the core part pattern of the optical waveguide array. It is explanatory drawing which showed the structure of the optical waveguide. It is explanatory drawing which showed the implementation method which guide | induces a several laser beam to an optical waveguide array. It is explanatory drawing which showed the manufacturing process of the optical waveguide array. It is explanatory drawing which showed the implementation method which guide | induces a several laser beam to an optical waveguide array. It is explanatory drawing which showed the implementation method which guide | induces a several laser beam to an optical waveguide array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... F (theta) lens, 3 ... Polygon mirror, 4 ... Cylindrical lens, 5 ... Lens, 6 ... Lens, 7 ... Collimator lens, 8 ... Optical fiber array, 9 ... Optical fiber, 91 ... Optical fiber clad part 92 ... Optical fiber core part, 10 ... Semiconductor laser module, 11 ... Semiconductor laser, 12 ... V-groove of silicon crystal, 13 ... Glass plate, 14 ... Adhesive, 15 ... Optical waveguide array, 16 ... Optical waveguide core part, DESCRIPTION OF SYMBOLS 17 ... Optical waveguide array output end surface, 18 ... Optical waveguide array incident end surface, 19 ... Under clad layer, 20 ... Optical waveguide core part, 21 ... Over clad layer, 22 ... Waveguide layer, 23 ... Chromium film, 24 ... Photoresist 25 ... lens, 26 ... lens.

Claims (8)

In an optical recording apparatus for optical recording by modulating and scanning a plurality of laser beams emitted from an optical waveguide array having a wavelength of 420 nm or less onto a photosensitive material, the optical waveguide array includes an underclad layer and a core on the underclad layer and parts made with the over-cladding layer covering the said core upper surface and the core side surface, the core portion is viewed including the Al ₂ O ₃ to SiO _2, optical, characterized in that the core diameter is more than 2μm An optical recording apparatus using a waveguide. _{2. The} optical recording apparatus using an optical waveguide array according to claim 1, wherein the material of the core portion includes 5 w% or less of Al ₂ O ₃ in SiO ₂ .   2. The optical recording apparatus using an optical waveguide array according to claim 1, wherein the under cladding layer is a quartz glass plate. 2. The optical recording apparatus using an optical waveguide array according to claim 1, wherein the under-cladding layer is a thermal oxide film on a Si wafer. _{2. The} optical recording apparatus using an optical waveguide array according to claim 1, wherein the over cladding layer is made of SiO2. 2. The optical recording apparatus using an optical waveguide array according to claim 1, wherein laser light is directly incident on each incident end face of the optical waveguide array from each semiconductor laser. 2. The light using an optical waveguide array according to claim 1, wherein the laser light emitted from each semiconductor laser is condensed and incident on each incident end face of the optical waveguide array using a lens. Recording device. An optical fiber array exit surface is connected to the entrance end face of the optical waveguide array, and laser light emitted from each semiconductor laser is incident on each optical fiber entrance surface of the optical fiber array, whereby laser light is incident on the optical waveguide array. The optical recording apparatus using the optical waveguide array according to claim 1, wherein:

Images