JP4710046B2 - Optical recording device - Google Patents

Description

  The present invention relates to an optical recording apparatus, and in particular, performs optical recording by scanning a photosensitive material with a plurality of laser beams using an optical waveguide array.

  In a laser printer that represents an optical recording device, when optical recording is performed by simultaneously scanning a plurality of laser beams with a rotating polygon mirror, even if the rotation speed of the rotating polygon mirror cannot be increased, the number of beams can be increased. realizable.

  As a method for generating a plurality of laser beams, there is a method using an optical fiber array. An optical recording apparatus that performs optical recording by scanning a photosensitive material with a plurality of laser beams using an optical fiber array is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-146023

  In Patent Document 1, a quartz glass plate is attached using an adhesive in order to prevent dust floating in the air from adhering to the emission end face of the optical fiber array and reducing the intensity of emitted light. . However, when a violet laser beam with a wavelength of 450 nm or less is used, the shape of the beam emitted from the optical fiber array is deformed because the adhesive used to attach the quartz glass to the optical fiber array emission end face is altered. Resulting in. The same phenomenon occurs when an optical waveguide array is used instead of the optical fiber array and quartz glass is attached to the output end face of the optical waveguide array.

  Further, violet laser light having a wavelength of 450 nm or less has a function of causing a chemical reaction with a volatile component such as an adhesive in a place having a high light intensity such as an emission end face of an optical fiber array or an optical waveguide array, thereby attaching a contaminant.

  The object of the present invention is to suppress the adhesion of contaminants to the output end face of the optical waveguide array even when violet laser light having a wavelength of 450 nm or less is used, and to reduce the influence even if contaminants adhere. An object of the present invention is to provide an optical recording apparatus using a light-guided optical waveguide array.

To solve the above problems, the present invention provides an optical recording apparatus for modulating the scanning laser beam following a plurality of wavelengths 450nm emitted from the optical waveguide array, it is scanned on a photosensitive material, the optical waveguide array, undercladding layer and a waveguide formed on the under-cladding layer, said and an under-cladding layer and the waveguide over is formed on the cladding layer, the emission end of the waveguide of the optical waveguide array, From the end surface of the under cladding layer and the end surface of the over cladding layer, the distance g satisfying the condition of the following formula,
g> π · d ₀ ² · n / 4λ
In addition, the thickness T of the over cladding layer and the thickness TT of the under cladding layer are expressed by the following formula T> T ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 / 2 + k / 2
TT> TT ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 / 2−k / 2
(Where d ₀ is the diameter of the beam emitted from the waveguide, n is the refractive index of the under-cladding layer and the over-cladding layer, λ is the wavelength of light, and k is the thickness of the waveguide).

more than

  Further, the under clad layer end face and the over clad layer end face coincide with each other.

  Further, a quartz glass plate is used for the under cladding layer.

  Further, a thermal oxide film of a silicon wafer with a thermal oxide film is used for the under cladding layer.

  By adopting the configuration of the present invention, it is possible to provide an optical recording apparatus using an optical waveguide array, in which the influence of contaminant adhesion that occurs when violet laser light is used is reduced.

The structure of the optical waveguide array in the present invention will be described with reference to FIG. The laser beam emitted from the waveguide 16 of the optical waveguide array has a beam diameter increased by diffraction. Assuming that the beam diameter of light emitted from the single mode waveguide is d ₀ , the beam diameter d _X at a distance X away from the waveguide exit end face 18 is expressed by the following equation.
d _X = (d ₀ ² · (1 + X ² / X ₀ ² )) ^0.5 (1)
Here, X ₀ = π · d ₀ ² · n / 4λ, λ is the wavelength of light, and n is the refractive index of the over cladding layer 19 and the under cladding layer 17.

The wavelength λ of light is 0.410 (μm), the beam diameter d ₀ of the beam emitted from the single mode waveguide is 3 (μm), and the refractive index n of the over cladding layer 19 and the under cladding layer 17 is 1.469, When the distance g from the waveguide exit end face 18 to the over clad layer end face 20 and the under clad layer end face 21 is 0.252 (mm), the beam emitted from the waveguide exit end face 18 causes the over clad layer end face 20 and the under clad layer The beam diameter d _X when reaching the end face 21 is 30 (μm), which is about 4% of the power intensity at the waveguide exit end face 18.

  As the power intensity is increased, the influence of the contaminant adhesion due to the photochemical reaction becomes more prominent. Therefore, the structure of the optical waveguide array in the present invention can reduce the influence of the contaminant adhesion due to the photochemical reaction with the violet laser beam. .

Further, since the beam diameter becomes large, even if contaminants adhere to the emission end face, the influence is mitigated. However, when the distance g from the waveguide output end face 18 to the over clad layer end face 20 and the under clad layer end face 21 is g <X ₀ , the beam diameter d _X at the over clad layer end face 20 and the under clad layer end face 21 is the maximum. But not increased only 1.4 times that of d _0, is hardly conventional drawback is improved. Therefore, from the waveguide exit end face 18 of the optical waveguide array and the distance g to over cladding layer end surface 20 and the under cladding layer end surface 21, it is necessary to g> X _0.

Further, under the above conditions, when the over clad layer thickness T, the core diameter k = 2.5 (μm), and the under clad layer thickness TT,
T ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 /2+k/2=16.25 (μm) ( ² )
TT ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 / ²⁻ k / ² = 13.75 (μm) (3)
T ₀ + TT ₀ = 30 (μm) (4)
Therefore, when the thickness T of the over clad layer is T <T ₀ and the thickness TT of the under clad layer is TT <TT ₀ , the beams emitted from the over clad layer end face 20 and the under clad layer end face 21 are over It protrudes from the clad layer end face 20 and the under clad layer end face 21 and also exits from the over clad layer side face 22 and the under clad layer side face 23.

However, if the thickness T of the overcladding layer is T> T ₀ and the thickness TT of the undercladding layer is TT> TT ₀ , the emitted beams at the overcladding layer end face 20 and the undercladding layer end face 21 are 20 and the under clad layer end face 21 do not protrude. Therefore, the thickness T of the over cladding layer and the thickness TT of the under cladding layer need to satisfy T> T ₀ and TT> TT ₀ .

  Hereinafter, an embodiment of an optical recording apparatus using the optical waveguide array of the present invention will be described.

  FIG. 1 shows an optical system of an optical recording apparatus of the present invention. The light emitted from the semiconductor laser 6 is guided to the single mode optical fiber 5 by the lens in the LD module 7. A plurality of laser module parts are prepared, and the emission end face of each optical fiber is connected to the incident end face of the optical waveguide array 8. A plurality of laser beams emitted from the optical waveguide array are guided onto the polygon mirror 3 by the lens 4. The beam reflected on the polygon mirror 3 passes through the Fθ lens 2 and is then imaged and scanned on the photosensitive drum 1.

  FIG. 2 shows details of the configuration of the LD module unit. The semiconductor laser 6 is laser welded to the LDM holder 10. The light emitted from the semiconductor laser 6 is imaged on the end face 14 of the single mode optical fiber 5 by the lens 11. The single mode optical fiber 5 has a coating covering the optical fiber 5, and a 125 μm diameter cladding portion is exposed, inserted into the ferrule 13, and bonded. The ferrule 13 is further bonded to the ferrule holder 12. The ferrule holder 12 integrated with the single mode optical fiber 5 and the ferrule 13 is welded to the LDM holder 10 using laser welding.

FIG. 3 shows the structure of one embodiment of the optical waveguide array section. Waveguide is formed of a material doped with such GeO ₂ or TiO ₂ in the SiO _2, the under-cladding layer made of pure SiO _2, refractive index higher than the over cladding layer, 0.1 to 0.7 % Relative refractive index. An under clad layer 17 made of a quartz glass substrate or a silicon wafer with a thermal oxide film, and an SiO ₂ film to be an over clad layer 19 are formed on the waveguide 16 using a flame deposition method, a CVD method or the like. Further, the incident end face 15 of the optical waveguide array is polished, and the distance g from the waveguide outgoing end face 18 to the under clad layer end face 21 and the over clad layer end face 20 is g> π · d ₀ ² · n / 4λ. Thus, the under clad layer end face 21 and the over clad layer end face 20 are polished.

It is the schematic which shows the optical system of the optical recording apparatus of this invention. It is sectional drawing of the LD module part of the optical recording apparatus of this invention. It is the schematic which shows the optical waveguide array part of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... F (theta) lens, 3 ... Polygon mirror, 4 ... Lens, 5 ... Optical fiber, 6 ... Semiconductor laser, 7 ... LD module, 8 ... Optical waveguide array, 10 ... LDM holder, 11 ... Lens, 12 DESCRIPTION OF SYMBOLS ... Ferrule holder, 13 ... Ferrule, 14 ... Incident end face, 16 ... Waveguide, 17 ... Under clad layer, 18 ... Out end clad layer, 19 ... Over clad layer, 20 ... Over clad layer end face, 21 ... Under clad layer end face, 22 ... overclad layer side surface, 23 ... underclad layer side surface.

Claims (4)

In an optical recording apparatus that modulates and scans a plurality of laser beams having a wavelength of 450 nm or less emitted from an optical waveguide array and scans the photosensitive material,
The optical waveguide array includes an under cladding layer, a waveguide formed on the under-cladding layer, and an over cladding layer formed on the under-cladding layer and on the waveguide, the optical waveguide array The exit end of the waveguide is located at a distance g satisfying the following condition from the end surface of the under cladding layer and the end surface of the over cladding layer,
g> π · d ₀ ² · n / 4λ
In addition, the thickness T of the over cladding layer and the thickness TT of the under cladding layer are expressed by the following formula T> T ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 / 2 + k / 2
TT> TT ₀ = (d ₀ ² · (1 + g ² / X ₀ ² )) ^0.5 / 2−k / 2
(Where d ₀ is the beam diameter emitted from the waveguide, n is the refractive index of the under cladding layer and the over cladding layer, λ is the wavelength of light, and k is the thickness of the waveguide). Recording device.   The optical recording apparatus according to claim 1, wherein an end surface of the under cladding layer and an end surface of the over cladding layer coincide with each other.   3. The optical recording apparatus according to claim 1, wherein a quartz glass plate is used for the under cladding layer.   4. The optical recording apparatus according to claim 1, wherein a thermal oxide film of a silicon wafer with a thermal oxide film is used for the under cladding layer.

Images