WO2013018432A1 - Method for manufacturing and device for manufacturing optical waveguide circuit - Google Patents

Method for manufacturing and device for manufacturing optical waveguide circuit Download PDF

Info

Publication number
WO2013018432A1
WO2013018432A1 PCT/JP2012/064580 JP2012064580W WO2013018432A1 WO 2013018432 A1 WO2013018432 A1 WO 2013018432A1 JP 2012064580 W JP2012064580 W JP 2012064580W WO 2013018432 A1 WO2013018432 A1 WO 2013018432A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical waveguide
manufacturing
waveguide circuit
light
ultraviolet light
Prior art date
Application number
PCT/JP2012/064580
Other languages
French (fr)
Japanese (ja)
Inventor
泰芳 内田
津田　寿昭
奈良　一孝
Original Assignee
古河電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 古河電気工業株式会社 filed Critical 古河電気工業株式会社
Publication of WO2013018432A1 publication Critical patent/WO2013018432A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/13—Integrated optical circuits characterised by the manufacturing method
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
    • G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/125—Bends, branchings or intersections

Definitions

  • the present invention relates to an optical waveguide circuit manufacturing method and manufacturing apparatus.
  • MZI Mach-Zehnder interferometer
  • PLCs planar lightwave circuits
  • An optical interferometer element such as a diffraction grating (Arrayed-Waveguide Grating: AWG) is used.
  • These optical waveguide circuits include an optical waveguide including a core for guiding light and a clad formed around the core.
  • Such an optical interferometer element utilizes the interference action of light, if there is a manufacturing error in the optical path length of the optical waveguide, desired characteristics may not be obtained. Therefore, when manufacturing the optical interferometer element, there is a case where after the waveguide structure is manufactured, a step of irradiating a part of the core with ultraviolet light to increase the refractive index of the core. This process is also called a trimming process. Since the optical path length of the optical waveguide can be adjusted by this trimming process, the characteristics of the element can be adjusted.
  • the core contains germanium (Ge)
  • Ge absorbs ultraviolet light and changes the refractive index of the silica-based glass, which is a medium. Therefore, the refractive index of the core is increased by irradiation with ultraviolet light. Can do.
  • an ultraviolet light absorption coefficient of Ge contained in a core is increased by performing a hydrogen treatment process in which a MZI element having a waveguide structure is impregnated with hydrogen and then subjected to a heat treatment. This increases the sensitivity of the core to light-induced refractive index changes. Thereafter, a part of the core is irradiated with a laser beam of a KrF excimer laser (wavelength 248 nm) to adjust the characteristics of the element.
  • An ArF excimer laser (wavelength 193 nm) may be used as the ultraviolet light source.
  • a method for adjusting the characteristics of an element by irradiating an optical waveguide with ultraviolet light is not limited to an optical interferometer element (see Patent Documents 2 to 4).
  • the ultraviolet treatment for example, absorption at a wavelength of 248 nm
  • the refractive index of the cladding may change when the subsequent ultraviolet light irradiation is performed. Therefore, if there is a variation in the thickness of the clad or the content of B or P between elements or within the element, the element characteristics after adjustment may vary as in the case of the core, or desired characteristics may not be obtained. There is a further problem of being there.
  • the present invention has been made in view of the above, and an object of the present invention is to provide a method and an apparatus for manufacturing an optical waveguide circuit capable of adjusting characteristics by ultraviolet light irradiation with high accuracy.
  • an optical waveguide circuit manufacturing method includes a core containing a dopant that absorbs ultraviolet light and changes a refractive index of a medium, and a periphery of the core.
  • An ultraviolet light irradiation step of irradiating the core of the optical waveguide circuit comprising the clad formed with ultraviolet light, and a light emission amount measurement step of measuring the light emission amount from the dopant, and integrating the measured light emission amount The characteristics of the optical waveguide circuit are adjusted based on the values.
  • the irradiation of the ultraviolet light is stopped when the integrated value of the measured light emission amount reaches a predetermined value.
  • the dopant is germanium in the above invention.
  • the wavelength of the ultraviolet light is 193 nm in the above invention.
  • the wavelength of the ultraviolet light is 248 nm.
  • the cladding of the optical waveguide contains boron or phosphorus.
  • An optical waveguide circuit manufacturing apparatus includes an optical waveguide circuit including a core containing a dopant that absorbs ultraviolet light and changes a refractive index of a medium, and a clad formed around the core.
  • An ultraviolet light source for irradiating the core with ultraviolet light and a light emission amount measuring device for measuring the light emission amount from the dopant are provided, and the characteristics of the optical waveguide circuit are adjusted based on the integrated value of the measured light emission amount.
  • the optical waveguide circuit manufacturing apparatus further includes a controller that stops the irradiation of the ultraviolet light when the integrated value of the measured light emission amount reaches a predetermined value.
  • the dopant is germanium.
  • the ultraviolet light has a wavelength of 193 nm.
  • the wavelength of the ultraviolet light is 248 nm.
  • the clad of the optical waveguide contains boron or phosphorus.
  • the present invention it is possible to adjust the characteristics of the optical waveguide circuit by ultraviolet light irradiation with high accuracy.
  • FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the first embodiment.
  • FIG. 2 is a schematic plan view of one 90-degree hybrid element formed on the wafer shown in FIG.
  • FIG. 3A is a schematic cross-sectional view for explaining changes when a 90-degree hybrid element is irradiated with laser light.
  • FIG. 3B is a schematic cross-sectional view illustrating a change when the 90-degree hybrid element is irradiated with laser light.
  • FIG. 4 is a diagram showing the relationship between the laser beam irradiation time and the phase shift amount in different 90-degree hybrid element samples manufactured from the same wafer.
  • FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the first embodiment.
  • FIG. 2 is a schematic plan view of one 90-degree hybrid element formed on the wafer shown in FIG.
  • FIG. 3A is a schematic cross-sectional view for explaining changes when a
  • FIG. 5 is a diagram showing the relationship between the laser beam irradiation time and the phase shift amount in a sample of a 90-degree hybrid element fabricated from two different wafers.
  • FIG. 6 is a diagram showing the relationship between the light emission amount and the phase shift amount in samples of 90-degree hybrid elements manufactured from different wafers.
  • FIG. 7 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the second embodiment.
  • FIG. 8 is a schematic plan view of one AWG element formed on the wafer shown in FIG.
  • FIG. 9A is a schematic cross-sectional view illustrating a change when the AWG element is irradiated with laser light.
  • FIG. 9B is a schematic cross-sectional view illustrating a change when the AWG element is irradiated with laser light.
  • FIG. 10 is a diagram showing a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when an ArF excimer laser is used.
  • FIG. 11 is a diagram showing the relationship between the light emission amount and the wavelength shift amount in samples of different AWG elements manufactured from the same wafer.
  • FIG. 12 is a diagram illustrating a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when a KrF excimer laser is used.
  • FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the first embodiment.
  • the manufacturing apparatus 10 includes a KrF excimer laser 11, a mirror system 12a, a collimating lens system 13, a mirror 12b, a moving device 14, a light receiver 15, and a measurement controller 16. I have.
  • the KrF excimer laser 11 outputs laser light L1 having a wavelength of 248 nm, which is ultraviolet light.
  • the mirror system 12a, the collimating lens system 13, and the mirror 12b are arranged to collimate the laser light L1 and guide it to the wafer W1 placed on the moving device 14.
  • the beam diameter of the laser light L1 is adjusted to, for example, about 10 mm ⁇ 15 mm by the mirror system 12a, the collimating lens system 13, and the mirror 12b.
  • the moving device 14 is configured to place the wafer W1 on which a large number of 90-degree hybrid elements, which are optical waveguide circuits, are placed, and to move the wafer W1 in the left-right direction of the drawing sheet and in the direction perpendicular to the drawing sheet. Has been. As a result, the moving device 14 can adjust the position of the wafer W1 so that the laser light L1 is irradiated to a desired location on the wafer W1. Note that a shadow mask M1 is formed on the surface of the wafer W1 to cover a portion other than the place where the laser beam L1 is to be irradiated.
  • the light receiver 15 includes a photodiode, for example, and is arranged so as to receive light emitted from the 90-degree hybrid element.
  • the measurement controller 16 is connected to the light receiver 15.
  • the measurement controller 16 calculates an illuminance meter that measures the amount of light emitted from the 90-degree hybrid element based on the amount of light received by the light receiver 15 and an integrated value of the emitted light amount, and based on the integrated value, a KrF excimer laser 11 for controlling the controller 11.
  • FIG. 2 is a schematic plan view of one 90-degree hybrid element formed on the wafer shown in FIG.
  • one 90-degree hybrid element 1 includes input optical waveguides 1a and 1b, a Y branch optical waveguide 1c connected to the input optical waveguide 1a, and a Y branch optical waveguide 1d connected to the input optical waveguide 1b.
  • 3 dB composed of arm optical waveguides 1e and 1f connected to the Y branch optical waveguide 1c, arm optical waveguides 1g and 1h connected to the Y branch optical waveguide 1d, and a directional coupler connected to the arm optical waveguides 1e and 1g.
  • a coupler 1i, a 3 dB coupler 1j composed of a directional coupler connected to the arm optical waveguides 1f and 1h, output optical waveguides 1k and 1l connected to the 3 dB coupler 1i, and output optical waveguides 1m and 1n connected to the 3 dB coupler 1j And.
  • the arm optical waveguides 1e and 1f have the same optical path length.
  • the optical path length of the arm optical waveguide 1h and the optical path length of the arm optical waveguide 1g are set so that the optical path difference is 90 degrees in terms of the phase of light.
  • the optical path length of the arm optical waveguide 1h is set shorter than the optical path length of the arm optical waveguides 1e and 1f by ⁇ / 4 radians (45 degrees) in terms of the light phase
  • the optical path length of the arm optical waveguide 1g is It is set longer by ⁇ / 4 radians in terms of the phase of light than the optical path lengths of the optical waveguides 1e and 1f.
  • the 90-degree hybrid element 1 has an interference characteristic in which the phase is different by 90 degrees between the output characteristic of the 3 dB coupler 1 j and the 3 dB coupler 1 i.
  • This 90-degree hybrid element 1 transmits and transmits local oscillation (LO) light, for example, on the light receiving side of an optical transmission system using a polarization multiplexing quadrature phase shift keying (DP-QPSK) method. Used to mix and interfere with the later DP-QPSK optical signal.
  • LO local oscillation
  • DP-QPSK polarization multiplexing quadrature phase shift keying
  • the polarization-separated LO light and the DP-QPSK optical signal are input to the input optical waveguides 1a and 1b, mixed and interfered, and then output from the output optical waveguides 1k, 1l, 1m, and 1n, respectively. .
  • the light output from the output optical waveguides 1k, 1l, 1m, and 1n is received by a balanced photo detector (B-PD) to separate the I channel and the Q channel of the modulation signal and It can be taken out as a signal.
  • B-PD balanced photo detector
  • the design of the optical path lengths of the arm optical waveguides 1e, 1f, 1g, and 1h greatly affects the characteristics of the element.
  • a desired optical path length may not be obtained at the time of manufacturing the optical waveguide structure due to manufacturing variations and the like.
  • the optical path length is adjusted (trimmed) by the manufacturing apparatus 10 shown in FIG. 1 as follows.
  • hydrogen treatment is performed.
  • This hydrogen treatment is performed, for example, under a pressure of 15 MPa hydrogen gas for 7 days.
  • a wafer W1 subjected to hydrogen treatment is placed on the moving device 14.
  • the laser light L1 from the KrF excimer laser 11 is guided to the predetermined 90-degree hybrid element 1 by the mirror system 12a, the collimating lens system 13, and the mirror 12b, and the shadow mask M1
  • the optical path length is adjusted by irradiating one of the arm optical waveguides not covered with (for example, the arm optical waveguide 1e).
  • 3A and 3B are schematic cross-sectional views for explaining changes when a 90-degree hybrid element is irradiated with laser light.
  • the cores of all the optical waveguides including the arm optical waveguide 1e of the 90-degree hybrid element 1 are surrounded by a cladding layer 1p formed around the substrate 1o made of, for example, silicon. ing.
  • the core is doped with Ge
  • the cladding layer 1p is doped with B or P.
  • the size of the cross section of the core of the optical waveguide including the arm optical waveguide 1e is, for example, 6 ⁇ m ⁇ 6 ⁇ m.
  • Ge and B or P are added so that the relative refractive index difference of the core with respect to the cladding layer 1p is, for example, 0.75%.
  • a region 1q in FIG. 3B indicates a region where the refractive index has changed.
  • Ge that has absorbed the laser beam L1 does not emit light.
  • Ge that has absorbed the laser beam L1 emits fluorescence L2 including light having a wavelength of around 400 nm.
  • the light receiver 15 receives the Ge fluorescence L2 and outputs a current corresponding to the amount of light received.
  • the measurement controller 16 measures the light emission amount of Ge based on the current amount from the light receiver 15 and calculates an integrated value of the light emission amount. When the integrated value of the light emission amount reaches a predetermined value, the measurement controller 16 controls the KrF excimer laser 11 to stop the irradiation with the laser light L1. Thereby, the adjustment of the optical path length is completed.
  • the stop of the irradiation with the laser light L1 may be stopped by an operator based on the integrated value of the light emission amount displayed by the measurement controller 16.
  • the optical path length adjustment amount when adjusting the optical path length based on the irradiation time of the laser light L1 as in the conventional case, if there is a variation in the core size and the Ge content, even if the irradiation time is the same, Variations also occur in the amount of energy of the laser beam L1 absorbed by the core. As a result, the optical path length adjustment amount also varies.
  • B or P in the cladding layer 1p when a laser beam L1 having a wavelength of 248 nm such as the KrF excimer laser 11 is used, B or P in the cladding layer 1p also absorbs the laser beam L1. Therefore, B or P in the cladding layer 1p mainly absorbs the laser light L1 from the start of irradiation of the laser light L1 until a predetermined time, and after the absorption is saturated, Ge in the waveguide core of the arm optical waveguide 1e The absorption of the laser beam L1 is mainly performed. The time from the start of irradiation of the laser light L1 until the light absorption of B or P is saturated is also referred to as pre-irradiation time.
  • this pre-irradiation time varies depending on the variation in the thickness of the cladding layer 1p and the content of B or P, when adjusting the optical path length based on the irradiation time of the laser beam L1, the adjustment of the optical path length There is a risk that the amount of variation will be even greater.
  • the optical path length is adjusted based on the integrated value of the fluorescence emission amount proportional to the energy amount absorbed by Ge.
  • the amount of change in the refractive index of the core of the arm optical waveguide 1e irradiated with the laser light L1 is proportional to the amount of energy of the absorbed laser light L1. It is difficult to directly measure the amount of energy absorbed.
  • the optical path length can be accurately adjusted by controlling the irradiation time of the laser light L1 based on the integrated value of the light emission amount and adjusting the optical path length.
  • a 90-degree hybrid element 1 adjusted to a desired characteristic by performing a hydrogen removal process at a temperature of 80 ° C. for 48 hours and a characteristic stabilization process at a temperature of 300 ° C. or higher for 10 minutes. Can be manufactured.
  • the measurement result will be described.
  • FIG. 4 is a diagram showing the relationship between the irradiation time of the laser beam and the phase shift amount in different 90-degree hybrid element samples manufactured from the same wafer.
  • a solid line in FIG. 4 indicates an approximate straight line of data points by the least square method.
  • the amount of phase shift varies when the irradiation time is 40 seconds or less. This indicates that the pre-irradiation time varies. It can also be seen that when the phase shift amount is adjusted according to the irradiation time of the laser light, the phase shift amount varies even for samples manufactured from the same wafer.
  • FIG. 5 is a diagram showing the relationship between the irradiation time of the laser beam and the phase shift amount in a sample of a 90-degree hybrid element manufactured from two different wafers.
  • a solid line in FIG. 5 represents an approximate straight line of rhombus data points by a least square method for a sample from a certain wafer.
  • the broken line in FIG. 5 shows an approximate straight line of triangular data points according to the least square method for a sample from another wafer.
  • FIG. 5 shows that the phase shift amount further varies between samples manufactured from different wafers.
  • FIG. 6 is a diagram showing the relationship between the light emission amount and the phase shift amount in samples of 90-degree hybrid elements manufactured from different wafers. Solid lines in FIG. 6 indicate approximate straight lines of rhombus and triangle data points by the least square method.
  • the light emission amount is an integrated value from the start of laser light irradiation, and includes light emission measured during the pre-irradiation time.
  • the unit of the integrated value of the light emission amount is “J / cm 2 ”, and the scale of the horizontal axis in FIG. 6 is proportional to this unit. From FIG. 6, it can be seen that the integrated value of the light emission amount and the phase shift amount are in a proportional relationship and have very little variation.
  • the laser light irradiation is controlled based on the integrated value of the light emission amount and the optical path difference is adjusted, there is a variation in the content of B or P in the cladding layer or a variation in the content of Ge in the core.
  • the variation in the phase shift amount can be extremely reduced.
  • FIG. 7 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the second embodiment.
  • the manufacturing apparatus 20 includes an ArF excimer laser 21, a shutter 17, a mirror 12 b, a moving device 14, a light receiver 15, and a measurement controller 16.
  • the mirror 12b, the moving device 14, the light receiver 15, and the measurement controller 16 are the same as those of the manufacturing apparatus 10 shown in FIG.
  • the ArF excimer laser 21 outputs laser light L3 having a wavelength of 193 nm, which is ultraviolet light.
  • the shutter 17 has a function of reducing the beam diameter of the laser light L3.
  • the mirror 12b is disposed so as to guide the wafer W2 placed on the moving device 14.
  • the beam diameter of the laser beam L3 is adjusted to about 10 mm ⁇ 10 mm by the shutter 17, for example.
  • the moving device 14 places a wafer W2 on which a number of AWG elements, which are optical waveguide circuits, are formed, and adjusts the position of the wafer W2 so that the laser light L3 is irradiated to a desired location on the wafer W2. Can do.
  • a shadow mask M2 is formed on the surface of the wafer W2 to cover areas other than the place where the laser beam L3 is to be irradiated.
  • FIG. 8 is a schematic plan view of one AWG element formed on the wafer shown in FIG.
  • one AWG element 2 includes an input optical waveguide 2a, an input slab optical waveguide 2b, m (for example, 600) channel optical waveguides 2c, an output slab optical waveguide 2d, and n pieces. For example, 48 output optical waveguides 2e are connected in this order.
  • each channel optical waveguide 2c is set so as to increase with a constant optical path length difference ⁇ L from the inner circumference side toward the outer circumference side. That is, the optical path length difference between adjacent channel optical waveguides 2c is equal to ⁇ L.
  • the AWG element 2 receives each of the output optical waveguides from the input optical waveguide 2a when wavelength multiplexed signal light composed of signal light of wavelengths ⁇ 1,..., ⁇ n arranged at equal intervals on the light frequency is input. It is possible to separate and output signal lights having wavelengths ⁇ 1,.
  • the transmission spectrum between the input optical waveguide 2a and the output optical waveguide corresponding to the wavelength ⁇ 1 in the output optical waveguide 2e has a peak at which the transmittance is maximum at the wavelength ⁇ 1.
  • the design of the optical path length of each channel optical waveguide 2c greatly affects the characteristics of the element.
  • a desired optical path length may not be obtained at the time of manufacturing the optical waveguide structure due to manufacturing variations and the like.
  • the transmittance peak may deviate from a desired wavelength.
  • the optical path length is adjusted (trimmed) by the manufacturing apparatus 20 shown in FIG. 7 as follows.
  • hydrogen treatment is performed. This hydrogen treatment is performed, for example, under a pressure of 15 MPa hydrogen gas for 7 days.
  • the wafer W2 subjected to the hydrogen treatment is placed on the moving device 14.
  • the laser light L3 from the ArF excimer laser 21 is guided to a predetermined AWG element 2 via the shutter 17 and the mirror 12b, and the channel light not covered with the shadow mask M2
  • the entire waveguide 2c is irradiated to adjust the optical path length.
  • FIGS. 9A and 9B are schematic cross-sectional views for explaining changes when an AWG element is irradiated with laser light.
  • the cores of all optical waveguides including the channel optical waveguide 2c of the AWG element 2 are surrounded by a clad layer 2p formed around the substrate 2o made of, for example, silicon. .
  • the core is doped with Ge, and the cladding layer 2p is doped with B or P.
  • the size of the cross section of the core of each optical waveguide is, for example, 6 ⁇ m ⁇ 6 ⁇ m.
  • Ge and B or P are added so that the relative refractive index difference of the optical waveguide with respect to the cladding layer 2p is, for example, 0.75%.
  • the AWG element 2 When the AWG element 2 is irradiated with the laser light L3, Ge in the channel optical waveguide 2c absorbs the laser light L3, and the refractive index of the region irradiated with the laser light L3 changes.
  • B or P in the cladding layer 2p does not absorb the laser light L3 having a wavelength of 193 nm.
  • Ge that absorbed the laser beam L3 emits fluorescence L4 including light having a wavelength of around 400 nm.
  • the light receiver 15 receives the Ge fluorescence L4 and outputs a current corresponding to the amount of light received.
  • the measurement controller 16 measures the light emission amount of Ge based on the current amount from the light receiver 15 and calculates an integrated value of the light emission amount. When the integrated value of the light emission amount reaches a predetermined value, the measurement controller 16 controls the ArF excimer laser 21 to stop the irradiation with the laser light L3. This completes the adjustment of the optical path length (FIG. 9B). The stop of the irradiation with the laser beam L3 may be stopped by an operator based on the integrated value of the light emission amount displayed by the measurement controller 16.
  • the optical path length is adjusted based on the integrated value of the fluorescence emission amount proportional to the absorbed energy amount.
  • the amount of change in the refractive index of the core of the channel optical waveguide 2c irradiated with the laser light L3 is proportional to the energy amount of the absorbed laser light L3.
  • the optical path length can be adjusted accurately by controlling the irradiation time of the laser light L3 based on the integrated value of the light emission amount and adjusting the optical path length.
  • the laser light L3 having a wavelength of 193 nm of the ArF excimer laser 21 is used.
  • B or P in the cladding layer 2p does not absorb the laser beam, so that the problem of variations in pre-irradiation time does not occur. Therefore, the optical path length can be adjusted with higher accuracy.
  • the AWG element 2 adjusted to a desired characteristic is obtained.
  • the measurement result of the transmission spectrum when the optical path length is adjusted by irradiating the channel waveguide of the AWG element with laser light having a wavelength of 193 nm from the ArF excimer laser will be described.
  • FIG. 10 is a diagram showing a transmission spectrum before and after adjustment between an input optical waveguide and a predetermined output waveguide when an ArF excimer laser is used.
  • the transmission spectrum was measured using light of TM polarization (polarization in a direction perpendicular to the surface of the wafer on which the AWG element was formed).
  • FIG. 11 is a diagram showing the relationship between the light emission amount and the wavelength shift amount in samples of different AWG elements manufactured from the same wafer.
  • a solid line in FIG. 11 indicates an approximate straight line of data points by the least square method.
  • the light emission amount is an integrated value from the start of laser beam irradiation.
  • the unit of the integrated value of the light emission amount is “J / cm 2 ”, and the scale of the horizontal axis in FIG. 11 is proportional to this unit. From FIG. 11, it can be seen that the variation in the wavelength shift amount can be extremely reduced by controlling the irradiation of the laser beam based on the integrated value of the light emission amount and adjusting the optical path difference.
  • the transmission spectrum was measured when the optical waveguide length was adjusted by irradiating the channel waveguide of the AWG element with laser light having a wavelength of 248 nm from the KrF excimer laser as in the first embodiment.
  • FIG. 12 is a diagram showing a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when a KrF excimer laser is used.
  • the transmission spectrum was measured using TM polarized light.
  • the transmission peak wavelength related to a predetermined output waveguide can be similarly adjusted.
  • the refractive index of the cladding layer also changes because B or P of the cladding layer absorbs light.
  • the relative refractive index difference between the core and the cladding layer changes.
  • small transmission peaks appear on both sides of the central transmission peak. This indicates that the crosstalk between the channel optical waveguides in the AWG element is deteriorated by the adjustment for shifting the transmission peak wavelength. Therefore, in order to prevent such crosstalk degradation, it is preferable to perform adjustment using an ArF excimer laser.
  • the cladding layers of the 90-degree hybrid element and the AWG element that are optical waveguide circuits contain B or P, but B or P may not be contained.
  • the cladding layer does not contain B or P, for example, even when a KrF excimer laser is used, it is possible to prevent the above-described variation in pre-irradiation time and deterioration of crosstalk.
  • an excimer laser is used as an ultraviolet light source, but there is no particular limitation as long as it is a light source capable of outputting ultraviolet light.
  • the dopant added to the core is not limited to Ge, and is not particularly limited as long as the dopant can absorb the ultraviolet light to be irradiated and change the refractive index of the glass medium.
  • the 90-degree hybrid element and the AWG element are exemplified as the optical waveguide circuit.
  • the type of the optical waveguide circuit is particularly limited. It is not limited.
  • the optical waveguide circuit manufacturing method and manufacturing apparatus according to the present invention are suitable mainly in the field of optical communication.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

This manufacturing method for an optical waveguide circuit includes an ultraviolet light exposure step that exposes a core of an optical waveguide circuit, which is provided with a core containing a dopant that absorbs ultraviolet light and changes the index of refraction of a medium and a cladding formed around that core, to ultraviolet light and a light emission measuring step for measuring the amount of light emitted by the dopant. The characteristics of the optical waveguide circuit are adjusted on the basis of an integrated value for the amount of light measured. Thus, a method for manufacturing and a device for manufacturing an optical waveguide circuit in which the characteristics can he adjusted at high precision by ultraviolet light exposure are provided.

Description

光導波路回路の製造方法および製造装置Method and apparatus for manufacturing optical waveguide circuit
　本発明は、光導波路回路の製造方法および製造装置に関する。 The present invention relates to an optical waveguide circuit manufacturing method and manufacturing apparatus.
　主に光通信の分野において、石英系ガラスを材料とする光導波路回路である平面光波回路(Planar　Lightwave　Circuit：ＰＬＣ)により構成したマッハツェンダー光干渉計(Mach-Zehnder　interferometer：ＭＺＩ)やアレイ導波路回折格子(Arrayed-Waveguide　Grating：ＡＷＧ)などの光干渉計素子が用いられている。これらの光導波路回路は、光を導波するコアと、コアの周囲に形成されたクラッドとからなる光導波路を備えている。 Mainly in the field of optical communications, Mach-Zehnder interferometer (MZI) and arrayed waveguides composed of planar lightwave circuits (PLCs), which are optical waveguide circuits made of silica glass. An optical interferometer element such as a diffraction grating (Arrayed-Waveguide Grating: AWG) is used. These optical waveguide circuits include an optical waveguide including a core for guiding light and a clad formed around the core.
　このような光干渉計素子は光の干渉作用を利用しているため、光導波路の光路長等に製造誤差がある場合には、所望の特性が得られない場合がある。そこで、光干渉計素子の製造の際には、導波路構造を作製した後に、コアの一部分に紫外光を照射してコアの屈折率を高める工程が行われる場合がある。この工程はトリミング工程とも呼ばれる。このトリミング工程によって光導波路の光路長を調整することができるので、素子の特性を調整することができる。なお、コアがゲルマニウム（Ｇｅ）を含有している場合には、Ｇｅが紫外光を吸収して媒質である石英系ガラスの屈折率を変化させるので、紫外光照射によりコアの屈折率を高めることができる。 Since such an optical interferometer element utilizes the interference action of light, if there is a manufacturing error in the optical path length of the optical waveguide, desired characteristics may not be obtained. Therefore, when manufacturing the optical interferometer element, there is a case where after the waveguide structure is manufactured, a step of irradiating a part of the core with ultraviolet light to increase the refractive index of the core. This process is also called a trimming process. Since the optical path length of the optical waveguide can be adjusted by this trimming process, the characteristics of the element can be adjusted. When the core contains germanium (Ge), Ge absorbs ultraviolet light and changes the refractive index of the silica-based glass, which is a medium. Therefore, the refractive index of the core is increased by irradiation with ultraviolet light. Can do.
　たとえば、特許文献１では、導波路構造を作製したＭＺＩ素子に水素を含浸させた後、熱処理を行う水素処理工程を行うことによって、コアに含まれるＧｅの紫外光吸収係数を増大させている。これによってコアの光誘起屈折率変化の感受性を高めている。その後、コアの一部分にＫｒＦエキシマレーザのレーザ光（波長２４８ｎｍ）を照射して素子の特性を調整している。なお、紫外光源としてはＡｒＦエキシマレーザ（波長１９３ｎｍ）を用いる場合もある。また、光導波路に紫外光を照射して素子の特性を調整する方法は、光干渉計素子に限らず使用されている（特許文献２～４参照）。 For example, in Patent Document 1, an ultraviolet light absorption coefficient of Ge contained in a core is increased by performing a hydrogen treatment process in which a MZI element having a waveguide structure is impregnated with hydrogen and then subjected to a heat treatment. This increases the sensitivity of the core to light-induced refractive index changes. Thereafter, a part of the core is irradiated with a laser beam of a KrF excimer laser (wavelength 248 nm) to adjust the characteristics of the element. An ArF excimer laser (wavelength 193 nm) may be used as the ultraviolet light source. A method for adjusting the characteristics of an element by irradiating an optical waveguide with ultraviolet light is not limited to an optical interferometer element (see Patent Documents 2 to 4).
特開平０６－３０８５４６号公報Japanese Patent Laid-Open No. 06-308546 特開２００１－３１１８４７号公報JP 2001-31847 A 特開２００４－３１７８０２号公報JP 2004-317802 A 特開２００５－３１３５９号公報JP 2005-31359 A
　しかしながら、素子間または素子内でコアのサイズまたはＧｅの含有量にばらつきがある場合に、紫外光の照射時間の調整によってコアの屈折率の変化量を調整しようとすると、素子間または素子内でその調整量にばらつきが生じる。その結果調整後の素子特性にばらつきが生じたり、所望の特性が得られない場合があったりするという問題がある。 However, when there is a variation in the core size or Ge content between elements or within the element, if the amount of change in the refractive index of the core is adjusted by adjusting the irradiation time of the ultraviolet light, it is between elements or within the element. The adjustment amount varies. As a result, there is a problem that the element characteristics after adjustment may vary, or desired characteristics may not be obtained.
　特に、光導波路に水素処理工程を行う場合、光導波路のクラッドにホウ素（Ｂ）やリン（Ｐ）が添加されていると、水素処理によってクラッドの紫外光吸収（たとえば波長２４８ｎｍの吸収）も増大する場合がある。その結果、その後の紫外光照射を行った場合にクラッドの屈折率も変化する場合がある。したがって、素子間または素子内でクラッドの厚さやＢまたはＰの含有量にばらつきがあると、コアの場合と同様に調整後の素子特性にばらつきが生じたり、所望の特性が得られない場合があったりするというさらなる問題がある。 In particular, when a hydrogen treatment process is performed on an optical waveguide, if boron (B) or phosphorus (P) is added to the clad of the optical waveguide, the ultraviolet treatment (for example, absorption at a wavelength of 248 nm) of the clad is also increased by the hydrogen treatment. There is a case. As a result, the refractive index of the cladding may change when the subsequent ultraviolet light irradiation is performed. Therefore, if there is a variation in the thickness of the clad or the content of B or P between elements or within the element, the element characteristics after adjustment may vary as in the case of the core, or desired characteristics may not be obtained. There is a further problem of being there.
　本発明は、上記に鑑みてなされたものであって、紫外光照射による特性の調整を高精度にできる光導波路回路の製造方法および製造装置を提供することを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to provide a method and an apparatus for manufacturing an optical waveguide circuit capable of adjusting characteristics by ultraviolet light irradiation with high accuracy.
　上述した課題を解決し、目的を達成するために、本発明に係る光導波路回路の製造方法は、紫外光を吸収して媒質の屈折率を変化させるドーパントを含有するコアと該コアの周囲に形成されたクラッドとを備える光導波路回路の該コアに紫外光を照射する紫外光照射工程と、前記ドーパントからの発光量を測定する発光量測定工程と、を含み、前記測定した発光量の積算値に基づいて前記光導波路回路の特性を調整する。 In order to solve the above-described problems and achieve the object, an optical waveguide circuit manufacturing method according to the present invention includes a core containing a dopant that absorbs ultraviolet light and changes a refractive index of a medium, and a periphery of the core. An ultraviolet light irradiation step of irradiating the core of the optical waveguide circuit comprising the clad formed with ultraviolet light, and a light emission amount measurement step of measuring the light emission amount from the dopant, and integrating the measured light emission amount The characteristics of the optical waveguide circuit are adjusted based on the values.
　また、本発明に係る光導波路回路の製造方法は、上記発明において、前記測定した発光量の積算値が所定値に到達したときに前記紫外光の照射を停止する。 Further, in the method of manufacturing an optical waveguide circuit according to the present invention, in the above invention, the irradiation of the ultraviolet light is stopped when the integrated value of the measured light emission amount reaches a predetermined value.
　また、本発明に係る光導波路回路の製造方法は、上記発明において、前記ドーパントはゲルマニウムである。 Also, in the method of manufacturing an optical waveguide circuit according to the present invention, the dopant is germanium in the above invention.
　また、本発明に係る光導波路回路の製造方法は、上記発明において、前記紫外光の波長は波長１９３ｎｍである。 Further, in the method for manufacturing an optical waveguide circuit according to the present invention, the wavelength of the ultraviolet light is 193 nm in the above invention.
　また、本発明に係る光導波路回路の製造方法は、上記発明において、前記紫外光の波長は波長２４８ｎｍである。 Also, in the method for manufacturing an optical waveguide circuit according to the present invention, in the above invention, the wavelength of the ultraviolet light is 248 nm.
　また、本発明に係る光導波路回路の製造方法は、上記発明において、前記光導波路のクラッドはホウ素またはリンを含有する。 Also, in the method of manufacturing an optical waveguide circuit according to the present invention, in the above invention, the cladding of the optical waveguide contains boron or phosphorus.
　また、本発明に係る光導波路回路の製造装置は、紫外光を吸収して媒質の屈折率を変化させるドーパントを含有するコアと該コアの周囲に形成されたクラッドとを備える光導波路回路の該コアに紫外光を照射する紫外光源と、前記ドーパントからの発光量を測定する発光量測定器と、を備え、前記測定した発光量の積算値に基づいて前記光導波路回路の特性を調整する。 An optical waveguide circuit manufacturing apparatus according to the present invention includes an optical waveguide circuit including a core containing a dopant that absorbs ultraviolet light and changes a refractive index of a medium, and a clad formed around the core. An ultraviolet light source for irradiating the core with ultraviolet light and a light emission amount measuring device for measuring the light emission amount from the dopant are provided, and the characteristics of the optical waveguide circuit are adjusted based on the integrated value of the measured light emission amount.
　また、本発明に係る光導波路回路の製造装置は、上記発明において、前記測定した発光量の積算値が所定値に到達したときに前記紫外光の照射を停止する制御器を備える。 The optical waveguide circuit manufacturing apparatus according to the present invention further includes a controller that stops the irradiation of the ultraviolet light when the integrated value of the measured light emission amount reaches a predetermined value.
　また、本発明に係る光導波路回路の製造装置は、上記発明において、前記ドーパントはゲルマニウムである。 Also, in the optical waveguide circuit manufacturing apparatus according to the present invention, the dopant is germanium.
　また、本発明に係る光導波路回路の製造装置は、上記発明において、前記紫外光の波長は波長１９３ｎｍである。 In the optical waveguide circuit manufacturing apparatus according to the present invention, the ultraviolet light has a wavelength of 193 nm.
　また、本発明に係る光導波路回路の製造装置は、上記発明において、前記紫外光の波長は波長２４８ｎｍである。 In the optical waveguide circuit manufacturing apparatus according to the present invention, the wavelength of the ultraviolet light is 248 nm.
　また、本発明に係る光導波路回路の製造装置は、上記発明において、前記光導波路のクラッドはホウ素またはリンを含有する。 In the optical waveguide circuit manufacturing apparatus according to the present invention, the clad of the optical waveguide contains boron or phosphorus.
　本発明によれば、紫外光照射による光導波路回路の特性の調整を高精度にできるという効果を奏する。 According to the present invention, it is possible to adjust the characteristics of the optical waveguide circuit by ultraviolet light irradiation with high accuracy.
図１は、実施の形態１に係る光導波路回路の製造方法を実施するための製造装置の模式的な構成図である。FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the first embodiment. 図２は、図１に示すウェハに形成された１つの９０度ハイブリッド素子の模式的な平面図である。FIG. 2 is a schematic plan view of one 90-degree hybrid element formed on the wafer shown in FIG. 図３Ａは、９０度ハイブリッド素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。FIG. 3A is a schematic cross-sectional view for explaining changes when a 90-degree hybrid element is irradiated with laser light. 図３Ｂは、９０度ハイブリッド素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。FIG. 3B is a schematic cross-sectional view illustrating a change when the 90-degree hybrid element is irradiated with laser light. 図４は、同一のウェハから作製した異なる９０度ハイブリッド素子のサンプルにおけるレーザ光の照射時間と位相シフト量との関係を示す図である。FIG. 4 is a diagram showing the relationship between the laser beam irradiation time and the phase shift amount in different 90-degree hybrid element samples manufactured from the same wafer. 図５は、異なる２つのウェハから作製した９０度ハイブリッド素子のサンプルにおけるレーザ光の照射時間と位相シフト量との関係を示す図である。FIG. 5 is a diagram showing the relationship between the laser beam irradiation time and the phase shift amount in a sample of a 90-degree hybrid element fabricated from two different wafers. 図６は、異なるウェハから作製した９０度ハイブリッド素子のサンプルにおける発光量と位相シフト量との関係を示す図である。FIG. 6 is a diagram showing the relationship between the light emission amount and the phase shift amount in samples of 90-degree hybrid elements manufactured from different wafers. 図７は、実施の形態２に係る光導波路回路の製造方法を実施するための製造装置の模式的な構成図である。FIG. 7 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the second embodiment. 図８は、図７に示すウェハに形成された１つのＡＷＧ素子の模式的な平面図である。FIG. 8 is a schematic plan view of one AWG element formed on the wafer shown in FIG. 図９Ａは、ＡＷＧ素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。FIG. 9A is a schematic cross-sectional view illustrating a change when the AWG element is irradiated with laser light. 図９Ｂは、ＡＷＧ素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。FIG. 9B is a schematic cross-sectional view illustrating a change when the AWG element is irradiated with laser light. 図１０は、ＡｒＦエキシマレーザを用いた場合の、入力光導波路と所定の出力導波路との間の調整前後の透過スペクトルを示す図である。FIG. 10 is a diagram showing a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when an ArF excimer laser is used. 図１１は、同一ウェハから作製した異なるＡＷＧ素子のサンプルにおける発光量と波長シフト量との関係を示す図である。FIG. 11 is a diagram showing the relationship between the light emission amount and the wavelength shift amount in samples of different AWG elements manufactured from the same wafer. 図１２は、ＫｒＦエキシマレーザを用いた場合の、入力光導波路と所定の出力導波路との間の調整前後の透過スペクトルを示す図である。FIG. 12 is a diagram illustrating a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when a KrF excimer laser is used.
　以下に、図面を参照して本発明に係る光導波路回路の製造方法および製造装置の実施の形態を詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。また、各図面において、同一または対応する要素には適宜同一の符号を付している。 Embodiments of an optical waveguide circuit manufacturing method and manufacturing apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Moreover, in each drawing, the same code | symbol is attached | subjected suitably to the same or corresponding element.
（実施の形態１）
　図１は、実施の形態１に係る光導波路回路の製造方法を実施するための製造装置の模式的な構成図である。図１に示すように、この製造装置１０は、ＫｒＦエキシマレーザ１１と、ミラー系１２ａと、コリメートレンズ系１３と、ミラー１２ｂと、移動装置１４と、受光器１５と、測定制御器１６とを備えている。 (Embodiment 1)
FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the first embodiment. As shown in FIG. 1, the manufacturing apparatus 10 includes a KrF excimer laser 11, a mirror system 12a, a collimating lens system 13, a mirror 12b, a moving device 14, a light receiver 15, and a measurement controller 16. I have.
　ＫｒＦエキシマレーザ１１は、紫外光である波長２４８ｎｍのレーザ光Ｌ１を出力する。ミラー系１２ａ、コリメートレンズ系１３、およびミラー１２ｂは、レーザ光Ｌ１をコリメートし、移動装置１４に載置されたウェハＷ１に導くように配置されている。なお、ミラー系１２ａ、コリメートレンズ系１３、およびミラー１２ｂによって、レーザ光Ｌ１のビーム径はたとえば約１０ｍｍ×１５ｍｍに調整される。 The KrF excimer laser 11 outputs laser light L1 having a wavelength of 248 nm, which is ultraviolet light. The mirror system 12a, the collimating lens system 13, and the mirror 12b are arranged to collimate the laser light L1 and guide it to the wafer W1 placed on the moving device 14. The beam diameter of the laser light L1 is adjusted to, for example, about 10 mm × 15 mm by the mirror system 12a, the collimating lens system 13, and the mirror 12b.
　移動装置１４は、光導波路回路である多数の９０度ハイブリッド素子が形成されたウェハＷ１を載置するとともに、ウェハＷ１を、紙面の左右方向および紙面に垂直方向に移動させることができるように構成されている。これによって、移動装置１４は、レーザ光Ｌ１がウェハＷ１の所望の場所に照射されるように、ウェハＷ１の位置を調整することができる。なお、ウェハＷ１の表面には、レーザ光Ｌ１が照射されるべき場所以外を覆うシャドウマスクＭ１が形成されている。 The moving device 14 is configured to place the wafer W1 on which a large number of 90-degree hybrid elements, which are optical waveguide circuits, are placed, and to move the wafer W1 in the left-right direction of the drawing sheet and in the direction perpendicular to the drawing sheet. Has been. As a result, the moving device 14 can adjust the position of the wafer W1 so that the laser light L1 is irradiated to a desired location on the wafer W1. Note that a shadow mask M1 is formed on the surface of the wafer W1 to cover a portion other than the place where the laser beam L1 is to be irradiated.
　受光器１５は、たとえばフォトダイオードを備えており、９０度ハイブリッド素子からの発光を受光できるように配置されている。測定制御器１６は、受光器１５に接続されている。測定制御器１６は、受光器１５の受光量をもとに９０度ハイブリッド素子からの発光量を測定する照度計と、発光量の積算値を算出し、その積算値をもとにＫｒＦエキシマレーザ１１を制御する制御器とを備えている。 The light receiver 15 includes a photodiode, for example, and is arranged so as to receive light emitted from the 90-degree hybrid element. The measurement controller 16 is connected to the light receiver 15. The measurement controller 16 calculates an illuminance meter that measures the amount of light emitted from the 90-degree hybrid element based on the amount of light received by the light receiver 15 and an integrated value of the emitted light amount, and based on the integrated value, a KrF excimer laser 11 for controlling the controller 11.
　図２は、図１に示すウェハに形成された１つの９０度ハイブリッド素子の模式的な平面図である。図２に示すように、１つの９０度ハイブリッド素子１は、入力光導波路１ａ、１ｂと、入力光導波路１ａに接続したＹ分岐光導波路１ｃと、入力光導波路１ｂに接続したＹ分岐光導波路１ｄと、Ｙ分岐光導波路１ｃに接続したアーム光導波路１ｅ、１ｆと、Ｙ分岐光導波路１ｄに接続したアーム光導波路１ｇ、１ｈと、アーム光導波路１ｅ、１ｇに接続した方向性結合器からなる３ｄＢカプラ１ｉと、アーム光導波路１ｆ、１ｈに接続した方向性結合器からなる３ｄＢカプラ１ｊと、３ｄＢカプラ１ｉに接続した出力光導波路１ｋ、１ｌと、３ｄＢカプラ１ｊに接続した出力光導波路１ｍ、１ｎと、を備えている。 FIG. 2 is a schematic plan view of one 90-degree hybrid element formed on the wafer shown in FIG. As shown in FIG. 2, one 90-degree hybrid element 1 includes input optical waveguides 1a and 1b, a Y branch optical waveguide 1c connected to the input optical waveguide 1a, and a Y branch optical waveguide 1d connected to the input optical waveguide 1b. 3 dB composed of arm optical waveguides 1e and 1f connected to the Y branch optical waveguide 1c, arm optical waveguides 1g and 1h connected to the Y branch optical waveguide 1d, and a directional coupler connected to the arm optical waveguides 1e and 1g. A coupler 1i, a 3 dB coupler 1j composed of a directional coupler connected to the arm optical waveguides 1f and 1h, output optical waveguides 1k and 1l connected to the 3 dB coupler 1i, and output optical waveguides 1m and 1n connected to the 3 dB coupler 1j And.
　アーム光導波路１ｅ、１ｆは同じ光路長である。アーム光導波路１ｈの光路長とアーム光導波路１ｇの光路長とは、光路差が光の位相に換算して９０度となるように設定されている。たとえば、アーム光導波路１ｈの光路長はアーム光導波路１ｅ、１ｆの光路長よりも光の位相に換算してπ／４ラジアン（４５度）だけ短く設定され、アーム光導波路１ｇの光路長はアーム光導波路１ｅ、１ｆの光路長よりも光の位相に換算してπ／４ラジアンだけ長く設定されている。これによって、９０度ハイブリッド素子１は、３ｄＢカプラ１ｊの出力特性と３ｄＢカプラ１ｉとで位相が９０度異なる干渉特性を有する。 The arm optical waveguides 1e and 1f have the same optical path length. The optical path length of the arm optical waveguide 1h and the optical path length of the arm optical waveguide 1g are set so that the optical path difference is 90 degrees in terms of the phase of light. For example, the optical path length of the arm optical waveguide 1h is set shorter than the optical path length of the arm optical waveguides 1e and 1f by π / 4 radians (45 degrees) in terms of the light phase, and the optical path length of the arm optical waveguide 1g is It is set longer by π / 4 radians in terms of the phase of light than the optical path lengths of the optical waveguides 1e and 1f. Accordingly, the 90-degree hybrid element 1 has an interference characteristic in which the phase is different by 90 degrees between the output characteristic of the 3 dB coupler 1 j and the 3 dB coupler 1 i.
　この９０度ハイブリッド素子１は、たとえば偏波多重四値位相変調（ＤＰ－ＱＰＳＫ：Dual　Polarization　Quadrature　Phase　Shift　Keying）方式を用いる光伝送システムの受光側において、局所発振（Local　Oscillation：ＬＯ）光と伝送後のＤＰ－ＱＰＳＫ光信号とを混合させて干渉させるために用いられる。たとえば、偏波分離されたＬＯ光とＤＰ－ＱＰＳＫ光信号とが入力光導波路１ａ、１ｂのそれぞれに入力され、混合、干渉した後に出力光導波路１ｋ、１ｌ、１ｍ、１ｎのそれぞれから出力される。出力光導波路１ｋ、１ｌ、１ｍ、１ｎから出力された光をバランスドフォトディテクタ（Balanced-Photo　Detector：Ｂ－ＰＤ）で受光することによって、変調信号のＩチャネルとＱチャネルとを分離して、電気信号として取り出すことができる。 This 90-degree hybrid element 1 transmits and transmits local oscillation (LO) light, for example, on the light receiving side of an optical transmission system using a polarization multiplexing quadrature phase shift keying (DP-QPSK) method. Used to mix and interfere with the later DP-QPSK optical signal. For example, the polarization-separated LO light and the DP-QPSK optical signal are input to the input optical waveguides 1a and 1b, mixed and interfered, and then output from the output optical waveguides 1k, 1l, 1m, and 1n, respectively. . The light output from the output optical waveguides 1k, 1l, 1m, and 1n is received by a balanced photo detector (B-PD) to separate the I channel and the Q channel of the modulation signal and It can be taken out as a signal.
　この９０度ハイブリッド素子１では、アーム光導波路１ｅ、１ｆ、１ｇ、１ｈの光路長の設計が素子の特性に大きく影響を与える。しかしながら、製造ばらつきなどによって、光導波路構造の作製時には所望の光路長が得られない場合がある。 In the 90-degree hybrid element 1, the design of the optical path lengths of the arm optical waveguides 1e, 1f, 1g, and 1h greatly affects the characteristics of the element. However, a desired optical path length may not be obtained at the time of manufacturing the optical waveguide structure due to manufacturing variations and the like.
　そのため、本実施の形態１では、図１に示す製造装置１０によって以下のように光路長の調整（トリミング）を行う。 Therefore, in the first embodiment, the optical path length is adjusted (trimmed) by the manufacturing apparatus 10 shown in FIG. 1 as follows.
　はじめに、ウェハＷ１に９０度ハイブリッド素子１の光導波路構造を作製した後、水素処理を行う。この水素処理は、たとえば圧力１５ＭＰａ水素ガス下で７日間行う。 First, after producing an optical waveguide structure of the 90-degree hybrid element 1 on the wafer W1, hydrogen treatment is performed. This hydrogen treatment is performed, for example, under a pressure of 15 MPa hydrogen gas for 7 days.
　つぎに、図１に示すように移動装置１４に水素処理を行ったウェハＷ１を載置する。移動装置１４によってウェハＷ１の位置を調整した後、ＫｒＦエキシマレーザ１１からのレーザ光Ｌ１を、ミラー系１２ａ、コリメートレンズ系１３、およびミラー１２ｂによって所定の９０度ハイブリッド素子１に導き、シャドウマスクＭ１で覆われていないアーム光導波路のいずれか（たとえばアーム光導波路１ｅ）に照射し、光路長の調整を行う。 Next, as shown in FIG. 1, a wafer W1 subjected to hydrogen treatment is placed on the moving device 14. After the position of the wafer W1 is adjusted by the moving device 14, the laser light L1 from the KrF excimer laser 11 is guided to the predetermined 90-degree hybrid element 1 by the mirror system 12a, the collimating lens system 13, and the mirror 12b, and the shadow mask M1 The optical path length is adjusted by irradiating one of the arm optical waveguides not covered with (for example, the arm optical waveguide 1e).
　図３Ａ、３Ｂは、９０度ハイブリッド素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。図３Ａに示すように、９０度ハイブリッド素子１のアーム光導波路１ｅを含めたすべての光導波路のコアは、たとえばシリコンからなる基板１ｏの上で、その周囲に形成されたクラッド層１ｐに囲まれている。コアはＧｅが添加されており、クラッド層１ｐはＢまたはＰが添加されている。なお、アーム光導波路１ｅを含めた光導波路のコアの断面のサイズはたとえば６μｍ×６μｍである。またクラッド層１ｐに対するコアの比屈折率差がたとえば０．７５％となるようにＧｅおよびＢまたはＰが添加されている。 3A and 3B are schematic cross-sectional views for explaining changes when a 90-degree hybrid element is irradiated with laser light. As shown in FIG. 3A, the cores of all the optical waveguides including the arm optical waveguide 1e of the 90-degree hybrid element 1 are surrounded by a cladding layer 1p formed around the substrate 1o made of, for example, silicon. ing. The core is doped with Ge, and the cladding layer 1p is doped with B or P. The size of the cross section of the core of the optical waveguide including the arm optical waveguide 1e is, for example, 6 μm × 6 μm. Further, Ge and B or P are added so that the relative refractive index difference of the core with respect to the cladding layer 1p is, for example, 0.75%.
　９０度ハイブリッド素子１にレーザ光Ｌ１を照射すると、クラッド層１ｐ中のＢまたはＰ、およびアーム光導波路１ｅのコア中のＧｅがレーザ光Ｌ１を吸収する。これによって、アーム光導波路１ｅのコアおよびクラッド層１ｐのうち、レーザ光Ｌ１が照射された領域の屈折率が高くなるように変化する。このように屈折率を変化させることによって光路長を調整することができる。図３Ｂの領域１ｑは屈折率が変化した領域を示している。 When the 90-degree hybrid element 1 is irradiated with the laser light L1, B or P in the cladding layer 1p and Ge in the core of the arm optical waveguide 1e absorb the laser light L1. Thus, the refractive index of the region irradiated with the laser beam L1 in the core of the arm optical waveguide 1e and the cladding layer 1p is changed so as to increase. In this way, the optical path length can be adjusted by changing the refractive index. A region 1q in FIG. 3B indicates a region where the refractive index has changed.
　レーザ光Ｌ１を吸収したＢまたはＰは発光しない。これに対して、レーザ光Ｌ１を吸収したＧｅは波長４００ｎｍ付近の光を含む蛍光Ｌ２を発光する。受光器１５は、このＧｅの蛍光Ｌ２を受光してその受光量に対応する電流を出力する。測定制御器１６は、受光器１５からの電流量に基づいてＧｅの発光量を測定し、発光量の積算値を算出する。そして、この発光量の積算値が所定値に達したら、測定制御器１６がＫｒＦエキシマレーザ１１を制御して、レーザ光Ｌ１の照射を停止する。これによって、光路長の調整は終了する。なお、レーザ光Ｌ１の照射の停止は、測定制御器１６が表示する発光量の積算値に基づいて、作業者が停止作業を行っても良い。 B or P that has absorbed the laser beam L1 does not emit light. In contrast, Ge that has absorbed the laser beam L1 emits fluorescence L2 including light having a wavelength of around 400 nm. The light receiver 15 receives the Ge fluorescence L2 and outputs a current corresponding to the amount of light received. The measurement controller 16 measures the light emission amount of Ge based on the current amount from the light receiver 15 and calculates an integrated value of the light emission amount. When the integrated value of the light emission amount reaches a predetermined value, the measurement controller 16 controls the KrF excimer laser 11 to stop the irradiation with the laser light L1. Thereby, the adjustment of the optical path length is completed. The stop of the irradiation with the laser light L1 may be stopped by an operator based on the integrated value of the light emission amount displayed by the measurement controller 16.
　ここで、たとえば従来のようにレーザ光Ｌ１の照射時間に基づいて光路長を調整する場合は、コアのサイズやＧｅの含有量にばらつきがある場合には、同一の照射時間であっても、コアで吸収されるレーザ光Ｌ１のエネルギー量にもばらつきが生じる。その結果、光路長の調整量にもばらつきが生じる。 Here, for example, when adjusting the optical path length based on the irradiation time of the laser light L1 as in the conventional case, if there is a variation in the core size and the Ge content, even if the irradiation time is the same, Variations also occur in the amount of energy of the laser beam L1 absorbed by the core. As a result, the optical path length adjustment amount also varies.
　特に、ＫｒＦエキシマレーザ１１のような波長２４８ｎｍのレーザ光Ｌ１を用いた場合には、クラッド層１ｐ中のＢまたはＰもレーザ光Ｌ１を吸収する。そのため、レーザ光Ｌ１の照射開始から所定の時間まではクラッド層１ｐ中のＢまたはＰが主にレーザ光Ｌ１を吸収し、その吸収が飽和した後に、アーム光導波路１ｅの導波路コア中のＧｅによるレーザ光Ｌ１の吸収が主となる。レーザ光Ｌ１の照射開始から、ＢまたはＰの光吸収が飽和するまでの時間は、プレ照射時間とも呼ばれる。このプレ照射時間は、クラッド層１ｐの厚さのばらつきやＢまたはＰの含有量のばらつきに応じてばらつくので、レーザ光Ｌ１の照射時間に基づいて光路長を調整する場合は、光路長の調整量のばらつきがさらに大きくなるおそれがある。 In particular, when a laser beam L1 having a wavelength of 248 nm such as the KrF excimer laser 11 is used, B or P in the cladding layer 1p also absorbs the laser beam L1. Therefore, B or P in the cladding layer 1p mainly absorbs the laser light L1 from the start of irradiation of the laser light L1 until a predetermined time, and after the absorption is saturated, Ge in the waveguide core of the arm optical waveguide 1e The absorption of the laser beam L1 is mainly performed. The time from the start of irradiation of the laser light L1 until the light absorption of B or P is saturated is also referred to as pre-irradiation time. Since this pre-irradiation time varies depending on the variation in the thickness of the cladding layer 1p and the content of B or P, when adjusting the optical path length based on the irradiation time of the laser beam L1, the adjustment of the optical path length There is a risk that the amount of variation will be even greater.
　これに対して、本実施の形態１では、Ｇｅが吸収したエネルギー量に比例する蛍光の発光量の積算値に基づいて光路長を調整している。レーザ光Ｌ１が照射されたアーム光導波路１ｅのコアの屈折率の変化量は、吸収されたレーザ光Ｌ１のエネルギー量に比例する。吸収されたエネルギー量を直接測定することは困難である。しかしながら、本実施の形態１のように、発光量の積算値に基づきレーザ光Ｌ１の照射時間を制御し、光路長を調整することによって、精度よく光路長の調整を行うことができる。 In contrast, in the first embodiment, the optical path length is adjusted based on the integrated value of the fluorescence emission amount proportional to the energy amount absorbed by Ge. The amount of change in the refractive index of the core of the arm optical waveguide 1e irradiated with the laser light L1 is proportional to the amount of energy of the absorbed laser light L1. It is difficult to directly measure the amount of energy absorbed. However, as in the first embodiment, the optical path length can be accurately adjusted by controlling the irradiation time of the laser light L1 based on the integrated value of the light emission amount and adjusting the optical path length.
　なお、光路長の調整後は、たとえば温度８０℃で４８時間の水素抜き処理と温度３００℃以上で１０分間の特性安定化処理を行うことで、所望の特性に調整された９０度ハイブリッド素子１を製造することができる。 After the adjustment of the optical path length, for example, a 90-degree hybrid element 1 adjusted to a desired characteristic by performing a hydrogen removal process at a temperature of 80 ° C. for 48 hours and a characteristic stabilization process at a temperature of 300 ° C. or higher for 10 minutes. Can be manufactured.
　つぎに、実施の形態１に従い、９０度ハイブリッド素子のアーム導波路にＫｒＦエキシマレーザからの波長２４８ｎｍのレーザ光を照射して光路長を調整した場合の、３ｄＢカプラの干渉特性の位相シフト量の測定結果について説明する。 Next, according to the first embodiment, the phase shift amount of the interference characteristic of the 3 dB coupler when the optical path length is adjusted by irradiating the arm waveguide of the 90-degree hybrid element with the laser beam having a wavelength of 248 nm from the KrF excimer laser. The measurement result will be described.
　図４は、同一のウェハから作製した異なる９０度ハイブリッド素子のサンプルにおけるレーザ光の照射時間と位相シフト量との関係を示す図である。図４中の実線は、最小二乗法によるデータ点の近似直線を示している。図４において、照射時間が４０秒以下のときに位相シフト量がばらついている。このことはプレ照射時間がばらついていることを示している。また、レーザ光の照射時間によって位相シフト量を調整しようとした場合は、同じウェハから作製したサンプルであっても、位相シフト量にばらつきが生じることが分かる。 FIG. 4 is a diagram showing the relationship between the irradiation time of the laser beam and the phase shift amount in different 90-degree hybrid element samples manufactured from the same wafer. A solid line in FIG. 4 indicates an approximate straight line of data points by the least square method. In FIG. 4, the amount of phase shift varies when the irradiation time is 40 seconds or less. This indicates that the pre-irradiation time varies. It can also be seen that when the phase shift amount is adjusted according to the irradiation time of the laser light, the phase shift amount varies even for samples manufactured from the same wafer.
　図５は、異なる２つのウェハから作製した９０度ハイブリッド素子のサンプルにおけるレーザ光の照射時間と位相シフト量との関係を示す図である。図５中の実線は、あるウェハからのサンプルについての、最小二乗法によるひし形のデータ点の近似直線を示している。図５中の破線は、別のウェハからのサンプルについての、最小二乗法による三角形のデータ点の近似直線を示している。図５から、異なるウェハから作製したサンプル間ではさらに位相シフト量にばらつきが生じることが分かる。 FIG. 5 is a diagram showing the relationship between the irradiation time of the laser beam and the phase shift amount in a sample of a 90-degree hybrid element manufactured from two different wafers. A solid line in FIG. 5 represents an approximate straight line of rhombus data points by a least square method for a sample from a certain wafer. The broken line in FIG. 5 shows an approximate straight line of triangular data points according to the least square method for a sample from another wafer. FIG. 5 shows that the phase shift amount further varies between samples manufactured from different wafers.
　一方、図６は、異なるウェハから作製した９０度ハイブリッド素子のサンプルにおける発光量と位相シフト量との関係を示す図である。図６中の実線は、最小二乗法によるひし形および三角形のデータ点の近似直線を示している。なお、発光量は、レーザ光の照射開始時からの積算値であり、プレ照射時間において測定した発光も含まれている。発光量の積算値の単位は「Ｊ／ｃｍ２」であり、図６の横軸のスケールはこの単位に比例している。図６から、発光量の積算値と位相シフト量とは比例関係にあり、かつばらつきがきわめて少ないことが分かる。すなわち、発光量の積算値に基づいてレーザ光の照射を制御し、光路差を調整すれば、クラッド層のＢまたはＰの含有量のばらつきやコアのＧｅの含有量のばらつき等があったとしても、位相シフト量のばらつきをきわめて少なくできることが分かる。 On the other hand, FIG. 6 is a diagram showing the relationship between the light emission amount and the phase shift amount in samples of 90-degree hybrid elements manufactured from different wafers. Solid lines in FIG. 6 indicate approximate straight lines of rhombus and triangle data points by the least square method. The light emission amount is an integrated value from the start of laser light irradiation, and includes light emission measured during the pre-irradiation time. The unit of the integrated value of the light emission amount is “J / cm 2 ”, and the scale of the horizontal axis in FIG. 6 is proportional to this unit. From FIG. 6, it can be seen that the integrated value of the light emission amount and the phase shift amount are in a proportional relationship and have very little variation. That is, if the laser light irradiation is controlled based on the integrated value of the light emission amount and the optical path difference is adjusted, there is a variation in the content of B or P in the cladding layer or a variation in the content of Ge in the core. However, it can be seen that the variation in the phase shift amount can be extremely reduced.
（実施の形態２）
　図７は、実施の形態２に係る光導波路回路の製造方法を実施するための製造装置の模式的な構成図である。図７に示すように、この製造装置２０は、ＡｒＦエキシマレーザ２１と、シャッター１７と、ミラー１２ｂと、移動装置１４と、受光器１５と、測定制御器１６とを備えている。ミラー１２ｂ、移動装置１４、受光器１５、および測定制御器１６は図１に示す製造装置１０のものと同一である。 (Embodiment 2)
FIG. 7 is a schematic configuration diagram of a manufacturing apparatus for performing the method of manufacturing an optical waveguide circuit according to the second embodiment. As shown in FIG. 7, the manufacturing apparatus 20 includes an ArF excimer laser 21, a shutter 17, a mirror 12 b, a moving device 14, a light receiver 15, and a measurement controller 16. The mirror 12b, the moving device 14, the light receiver 15, and the measurement controller 16 are the same as those of the manufacturing apparatus 10 shown in FIG.
　ＡｒＦエキシマレーザ２１は、紫外光である波長１９３ｎｍのレーザ光Ｌ３を出力する。シャッター１７はレーザ光Ｌ３のビーム径を絞る機能を有する。ミラー１２ｂは、移動装置１４に載置されたウェハＷ２に導くように配置されている。レーザ光Ｌ３のビーム径はシャッター１７によってたとえば約１０ｍｍ×１０ｍｍに調整される。 The ArF excimer laser 21 outputs laser light L3 having a wavelength of 193 nm, which is ultraviolet light. The shutter 17 has a function of reducing the beam diameter of the laser light L3. The mirror 12b is disposed so as to guide the wafer W2 placed on the moving device 14. The beam diameter of the laser beam L3 is adjusted to about 10 mm × 10 mm by the shutter 17, for example.
　移動装置１４は、光導波路回路である多数のＡＷＧ素子が形成されたウェハＷ２を載置するとともに、レーザ光Ｌ３がウェハＷ２の所望の場所に照射されるようにウェハＷ２の位置を調整することができる。ウェハＷ２の表面には、レーザ光Ｌ３が照射されるべき場所以外を覆うシャドウマスクＭ２が形成されている。 The moving device 14 places a wafer W2 on which a number of AWG elements, which are optical waveguide circuits, are formed, and adjusts the position of the wafer W2 so that the laser light L3 is irradiated to a desired location on the wafer W2. Can do. A shadow mask M2 is formed on the surface of the wafer W2 to cover areas other than the place where the laser beam L3 is to be irradiated.
　図８は、図７に示すウェハに形成された１つのＡＷＧ素子の模式的な平面図である。図８に示すように、１つのＡＷＧ素子２は、入力光導波路２ａと、入力スラブ光導波路２ｂと、ｍ本（たとえば６００本）のチャネル光導波路２ｃと、出力スラブ光導波路２ｄと、ｎ本（たとえば４８本）の出力光導波路２ｅとがこの順に接続されて構成されている。 FIG. 8 is a schematic plan view of one AWG element formed on the wafer shown in FIG. As shown in FIG. 8, one AWG element 2 includes an input optical waveguide 2a, an input slab optical waveguide 2b, m (for example, 600) channel optical waveguides 2c, an output slab optical waveguide 2d, and n pieces. For example, 48 output optical waveguides 2e are connected in this order.
　ここで、各チャネル光導波路２ｃの光路長は、内周側から外周側に向かって一定の光路長差ΔＬで増加するように設定されている。すなわち、隣接するチャネル光導波路２ｃ間の光路長差は等しくΔＬである。これによって、ＡＷＧ素子２は、入力光導波路２ａから、光の周波数上に等間隔に配列した波長λ１、・・、λｎの信号光からなる波長多重信号光を入力した場合に、各出力光導波路２ｅからそれぞれ波長λ１、・・、λｎの信号光を分離して出力することができる。このとき、たとえば入力光導波路２ａと、出力光導波路２ｅのうち波長λ１に対応する出力光導波路との間の透過スペクトルは、波長λ１において透過率が最大となるピークを有する。 Here, the optical path length of each channel optical waveguide 2c is set so as to increase with a constant optical path length difference ΔL from the inner circumference side toward the outer circumference side. That is, the optical path length difference between adjacent channel optical waveguides 2c is equal to ΔL. As a result, the AWG element 2 receives each of the output optical waveguides from the input optical waveguide 2a when wavelength multiplexed signal light composed of signal light of wavelengths λ1,..., Λn arranged at equal intervals on the light frequency is input. It is possible to separate and output signal lights having wavelengths λ1,. At this time, for example, the transmission spectrum between the input optical waveguide 2a and the output optical waveguide corresponding to the wavelength λ1 in the output optical waveguide 2e has a peak at which the transmittance is maximum at the wavelength λ1.
　このＡＷＧ素子２では、各チャネル光導波路２ｃの光路長の設計が素子の特性に大きく影響を与える。しかしながら、製造ばらつきなどによって、光導波路構造の作製時には所望の光路長が得られない場合がある。その結果、入力光導波路２ａと各出力光導波路２ｅとの透過スペクトルにおいて、透過率のピークが所望の波長からずれてしまう場合がある。 In the AWG element 2, the design of the optical path length of each channel optical waveguide 2c greatly affects the characteristics of the element. However, a desired optical path length may not be obtained at the time of manufacturing the optical waveguide structure due to manufacturing variations and the like. As a result, in the transmission spectrum of the input optical waveguide 2a and each output optical waveguide 2e, the transmittance peak may deviate from a desired wavelength.
　そのため、本実施の形態２では、図７に示す製造装置２０によって以下のように光路長の調整（トリミング）を行う。 Therefore, in the second embodiment, the optical path length is adjusted (trimmed) by the manufacturing apparatus 20 shown in FIG. 7 as follows.
　はじめに、ウェハＷ２にＡＷＧ素子２の光導波路構造を作製した後、水素処理を行う。この水素処理は、たとえば圧力１５ＭＰａ水素ガス下で７日間行う。 First, after the optical waveguide structure of the AWG element 2 is fabricated on the wafer W2, hydrogen treatment is performed. This hydrogen treatment is performed, for example, under a pressure of 15 MPa hydrogen gas for 7 days.
　つぎに、移動装置１４に水素処理を行ったウェハＷ２を載置する。移動装置１４によってウェハＷ２の位置を調整した後、ＡｒＦエキシマレーザ２１からのレーザ光Ｌ３を、シャッター１７およびミラー１２ｂを介して所定のＡＷＧ素子２に導き、シャドウマスクＭ２で覆われていないチャネル光導波路２ｃ全体に照射し、光路長の調整を行う。 Next, the wafer W2 subjected to the hydrogen treatment is placed on the moving device 14. After the position of the wafer W2 is adjusted by the moving device 14, the laser light L3 from the ArF excimer laser 21 is guided to a predetermined AWG element 2 via the shutter 17 and the mirror 12b, and the channel light not covered with the shadow mask M2 The entire waveguide 2c is irradiated to adjust the optical path length.
　図９Ａ、９Ｂは、ＡＷＧ素子にレーザ光を照射した場合の変化を説明する模式的な断面図である。図９Ａに示すように、ＡＷＧ素子２のチャネル光導波路２ｃを含めたすべての光導波路のコアは、たとえばシリコンからなる基板２ｏの上で、その周囲に形成されたクラッド層２ｐに囲まれている。コアはＧｅが添加されており、クラッド層２ｐはＢまたはＰが添加されている。なお、各光導波路のコアの断面のサイズはたとえば６μｍ×６μｍである。クラッド層２ｐに対する光導波路の比屈折率差がたとえば０．７５％となるようにＧｅおよびＢまたはＰが添加されている。 FIGS. 9A and 9B are schematic cross-sectional views for explaining changes when an AWG element is irradiated with laser light. As shown in FIG. 9A, the cores of all optical waveguides including the channel optical waveguide 2c of the AWG element 2 are surrounded by a clad layer 2p formed around the substrate 2o made of, for example, silicon. . The core is doped with Ge, and the cladding layer 2p is doped with B or P. The size of the cross section of the core of each optical waveguide is, for example, 6 μm × 6 μm. Ge and B or P are added so that the relative refractive index difference of the optical waveguide with respect to the cladding layer 2p is, for example, 0.75%.
　ＡＷＧ素子２にレーザ光Ｌ３を照射すると、チャネル光導波路２ｃ中のＧｅがレーザ光Ｌ３を吸収し、レーザ光Ｌ３が照射された領域の屈折率が高くなるように変化する。ただし、ＫｒＦエキシマレーザを使用した実施の形態１の場合とは異なり、クラッド層２ｐ中のＢまたはＰは波長１９３ｎｍのレーザ光Ｌ３を吸収しない。 When the AWG element 2 is irradiated with the laser light L3, Ge in the channel optical waveguide 2c absorbs the laser light L3, and the refractive index of the region irradiated with the laser light L3 changes. However, unlike the case of the first embodiment using a KrF excimer laser, B or P in the cladding layer 2p does not absorb the laser light L3 having a wavelength of 193 nm.
　レーザ光Ｌ３を吸収したＧｅは波長４００ｎｍ付近の光を含む蛍光Ｌ４を発光する。受光器１５は、このＧｅの蛍光Ｌ４を受光してその受光量に対応する電流を出力する。測定制御器１６は、受光器１５からの電流量に基づいてＧｅの発光量を測定し、発光量の積算値を算出する。そして、この発光量の積算値が所定値に達したら、測定制御器１６がＡｒＦエキシマレーザ２１を制御して、レーザ光Ｌ３の照射を停止する。これによって、光路長の調整は終了する（図９Ｂ）。なお、レーザ光Ｌ３の照射の停止は、測定制御器１６が表示する発光量の積算値に基づいて、作業者が停止作業を行っても良い。 Ge that absorbed the laser beam L3 emits fluorescence L4 including light having a wavelength of around 400 nm. The light receiver 15 receives the Ge fluorescence L4 and outputs a current corresponding to the amount of light received. The measurement controller 16 measures the light emission amount of Ge based on the current amount from the light receiver 15 and calculates an integrated value of the light emission amount. When the integrated value of the light emission amount reaches a predetermined value, the measurement controller 16 controls the ArF excimer laser 21 to stop the irradiation with the laser light L3. This completes the adjustment of the optical path length (FIG. 9B). The stop of the irradiation with the laser beam L3 may be stopped by an operator based on the integrated value of the light emission amount displayed by the measurement controller 16.
　本実施の形態２では、実施の形態１と同様に、吸収したエネルギー量に比例する蛍光の発光量の積算値に基づいて光路長を調整している。レーザ光Ｌ３が照射されたチャネル光導波路２ｃのコアの屈折率の変化量は、吸収されたレーザ光Ｌ３のエネルギー量に比例する。本実施の形態２のように、発光量の積算値に基づきレーザ光Ｌ３の照射時間を制御し、光路長を調整することによって、精度よく光路長の調整を行うことができる。 In the second embodiment, as in the first embodiment, the optical path length is adjusted based on the integrated value of the fluorescence emission amount proportional to the absorbed energy amount. The amount of change in the refractive index of the core of the channel optical waveguide 2c irradiated with the laser light L3 is proportional to the energy amount of the absorbed laser light L3. As in the second embodiment, the optical path length can be adjusted accurately by controlling the irradiation time of the laser light L3 based on the integrated value of the light emission amount and adjusting the optical path length.
　特に、本実施の形態２では、ＡｒＦエキシマレーザ２１の波長１９３ｎｍのレーザ光Ｌ３を使用している。その結果、クラッド層２ｐ中のＢまたはＰはレーザ光を吸収しないので、プレ照射時間のばらつきの問題が発生しない。したがって、よりいっそう精度よく光路長の調整を行うことができる。 In particular, in the second embodiment, the laser light L3 having a wavelength of 193 nm of the ArF excimer laser 21 is used. As a result, B or P in the cladding layer 2p does not absorb the laser beam, so that the problem of variations in pre-irradiation time does not occur. Therefore, the optical path length can be adjusted with higher accuracy.
　なお、光路長の調整後は、たとえば温度８０℃で４８時間の水素抜き処理と温度３００℃以上で１０分間の特性安定化処理とを行うことで、所望の特性に調整されたＡＷＧ素子２を製造することができる。 After adjusting the optical path length, for example, by performing a hydrogen removal process at a temperature of 80 ° C. for 48 hours and a characteristic stabilization process at a temperature of 300 ° C. or more for 10 minutes, the AWG element 2 adjusted to a desired characteristic is obtained. Can be manufactured.
　つぎに、実施の形態２に従い、ＡＷＧ素子のチャネル導波路にＡｒＦエキシマレーザからの波長１９３ｎｍのレーザ光を照射して光路長を調整した場合の透過スペクトルの測定結果について説明する。 Next, according to the second embodiment, the measurement result of the transmission spectrum when the optical path length is adjusted by irradiating the channel waveguide of the AWG element with laser light having a wavelength of 193 nm from the ArF excimer laser will be described.
　図１０は、ＡｒＦエキシマレーザを用いた場合の、入力光導波路と所定の出力導波路との間の調整前後の透過スペクトルを示す図である。なお、透過スペクトルは、ＴＭ偏波（ＡＷＧ素子を形成したウェハの表面に垂直方向の偏波）の光を用いて測定した。 FIG. 10 is a diagram showing a transmission spectrum before and after adjustment between an input optical waveguide and a predetermined output waveguide when an ArF excimer laser is used. The transmission spectrum was measured using light of TM polarization (polarization in a direction perpendicular to the surface of the wafer on which the AWG element was formed).
　図１０に示すように、トリミングを行って光路長を調整することによって、所定の出力導波路に関する透過ピーク波長をシフトする調整を行うことができる。 As shown in FIG. 10, by adjusting the optical path length by trimming, it is possible to adjust the shift of the transmission peak wavelength related to a predetermined output waveguide.
　図１１は、同一ウェハから作製した異なるＡＷＧ素子のサンプルにおける発光量と波長シフト量との関係を示す図である。図１１中の実線は、最小二乗法によるデータ点の近似直線を示している。なお、発光量は、レーザ光の照射開始時からの積算値である。発光量の積算値の単位は「Ｊ／ｃｍ２」であり、図１１の横軸のスケールはこの単位に比例している。図１１から、発光量の積算値に基づいてレーザ光の照射を制御し、光路差を調整すれば、波長シフト量のばらつきをきわめて少なくできることが分かる。 FIG. 11 is a diagram showing the relationship between the light emission amount and the wavelength shift amount in samples of different AWG elements manufactured from the same wafer. A solid line in FIG. 11 indicates an approximate straight line of data points by the least square method. The light emission amount is an integrated value from the start of laser beam irradiation. The unit of the integrated value of the light emission amount is “J / cm 2 ”, and the scale of the horizontal axis in FIG. 11 is proportional to this unit. From FIG. 11, it can be seen that the variation in the wavelength shift amount can be extremely reduced by controlling the irradiation of the laser beam based on the integrated value of the light emission amount and adjusting the optical path difference.
　つぎに、ＡＷＧ素子のチャネル導波路に、実施の形態１のようにＫｒＦエキシマレーザからの波長２４８ｎｍのレーザ光を照射して光路長を調整した場合の透過スペクトルを測定した。 Next, the transmission spectrum was measured when the optical waveguide length was adjusted by irradiating the channel waveguide of the AWG element with laser light having a wavelength of 248 nm from the KrF excimer laser as in the first embodiment.
　図１２は、ＫｒＦエキシマレーザを用いた場合の、入力光導波路と所定の出力導波路との間の調整前後の透過スペクトルを示す図である。なお、透過スペクトルは、ＴＭ偏波の光を用いて測定した。 FIG. 12 is a diagram showing a transmission spectrum before and after adjustment between the input optical waveguide and a predetermined output waveguide when a KrF excimer laser is used. The transmission spectrum was measured using TM polarized light.
　図１２に示すように、ＫｒＦエキシマレーザを用いた場合も同様に、所定の出力導波路に関する透過ピーク波長をシフトする調整を行うことができる。ただし、ＫｒＦエキシマレーザを用いた場合は、クラッド層のＢまたはＰが光を吸収するため、クラッド層の屈折率も変化する。その結果、コアとクラッド層との間の比屈折率差が変化してしまう。これによって、図１２に示すように、調整後の透過スペクトルにおいては、中央の透過ピークの両側に小さい透過ピークが現れる。このことは、透過ピーク波長をシフトする調整によって、ＡＷＧ素子におけるチャネル光導波路間のクロストークが劣化したことを示している。したがって、このようなクロストークの劣化を防止するためには、ＡｒＦエキシマレーザを用いて調整を行うことが好ましい。 As shown in FIG. 12, when a KrF excimer laser is used, the transmission peak wavelength related to a predetermined output waveguide can be similarly adjusted. However, when a KrF excimer laser is used, the refractive index of the cladding layer also changes because B or P of the cladding layer absorbs light. As a result, the relative refractive index difference between the core and the cladding layer changes. As a result, as shown in FIG. 12, in the adjusted transmission spectrum, small transmission peaks appear on both sides of the central transmission peak. This indicates that the crosstalk between the channel optical waveguides in the AWG element is deteriorated by the adjustment for shifting the transmission peak wavelength. Therefore, in order to prevent such crosstalk degradation, it is preferable to perform adjustment using an ArF excimer laser.
　なお、上記実施の形態では、光導波路回路である９０度ハイブリッド素子およびＡＷＧ素子のクラッド層はＢまたはＰを含有しているが、ＢまたはＰは含有されていなくてもよい。クラッド層にＢまたはＰが含有されていない場合は、たとえばＫｒＦエキシマレーザを用いる場合でも、上記のようなプレ照射時間のばらつきや、クロストークの劣化を発生しないようにできる。 In the above embodiment, the cladding layers of the 90-degree hybrid element and the AWG element that are optical waveguide circuits contain B or P, but B or P may not be contained. When the cladding layer does not contain B or P, for example, even when a KrF excimer laser is used, it is possible to prevent the above-described variation in pre-irradiation time and deterioration of crosstalk.
　また、上記実施の形態では、紫外光源としてエキシマレーザを使用しているが、紫外光を出力できる光源であれば特に限定されない。また、コアに添加するドーパントはＧｅに限らず、照射する紫外光を吸収してガラス媒質の屈折率を変化させることができるドーパントであれば特に限定されない。 In the above embodiment, an excimer laser is used as an ultraviolet light source, but there is no particular limitation as long as it is a light source capable of outputting ultraviolet light. The dopant added to the core is not limited to Ge, and is not particularly limited as long as the dopant can absorb the ultraviolet light to be irradiated and change the refractive index of the glass medium.
　また、上記実施の形態では、光導波路回路として９０度ハイブリッド素子およびＡＷＧ素子を例示しているが、コアの屈折率を変化させて特性を調整できるものであれば、光導波路回路の種類は特に限定されない。 In the above embodiment, the 90-degree hybrid element and the AWG element are exemplified as the optical waveguide circuit. However, if the characteristics can be adjusted by changing the refractive index of the core, the type of the optical waveguide circuit is particularly limited. It is not limited.
　また、上記各実施の形態により本発明が限定されるものではない。上記各実施形態の各構成要素を適宜組み合わせて構成したものも本発明に含まれる。また、さらなる効果や変形例は、当業者によって容易に導き出すことができる。よって、本発明のより広範な態様は、上記の実施の形態に限定されるものではなく、様々な変更が可能である。 Further, the present invention is not limited by the above embodiments. What comprised each component of each said embodiment combining suitably is also contained in this invention. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.
　以上のように、本発明に係る光導波路回路の製造方法および製造装置は、主に光通信の分野において好適なものである。 As described above, the optical waveguide circuit manufacturing method and manufacturing apparatus according to the present invention are suitable mainly in the field of optical communication.
　１　９０度ハイブリッド素子
　１ａ、１ｂ、２ａ　入力光導波路
　１ｃ、１ｄ　Ｙ分岐光導波路
　１ｅ、１ｆ、１ｇ、１ｈ　アーム光導波路
　１ｉ、１ｊ　３ｄＢカプラ
　１ｋ、１ｌ、１ｍ、１ｎ、２ｅ　出力光導波路
　１ｏ、２ｏ　基板
　１ｐ、２ｐ　クラッド層
　１ｑ　領域
　２　ＡＷＧ素子
　２ｂ　入力スラブ光導波路
　２ｃ　チャネル光導波路
　２ｄ　出力スラブ光導波路
　１０、２０　製造装置
　１１　ＫｒＦエキシマレーザ
　１２ａ　ミラー系
　１２ｂ　ミラー
　１３　コリメートレンズ系
　１４　移動装置
　１５　受光器
　１６　測定制御器
　１７　シャッター
　２１　ＡｒＦエキシマレーザ
　Ｌ１、Ｌ３　レーザ光
　Ｌ２、Ｌ４　蛍光
　Ｍ１、Ｍ２　シャドウマスク
　Ｗ１、Ｗ２　ウェハ 1 90-degree hybrid elements 1a, 1b, 2a input optical waveguide 1c, 1d Y branch optical waveguide 1e, 1f, 1g, 1h arm optical waveguides 1i, 1j 3 dB coupler 1k, 1l, 1m, 1n, 2e output optical waveguide 1o, 2o substrate 1p, 2p cladding layer 1q region 2 AWG element 2b input slab waveguide 2c channel optical waveguide 2d output slab waveguide 10, 20 manufacturing apparatus 11 KrF excimer laser 12a mirror system 12b mirror 13 collimating lens system 14 moving device 15 light receiver 16 Measurement controller 17 Shutter 21 ArF excimer laser L1, L3 Laser light L2, L4 Fluorescence M1, M2 Shadow mask W1, W2 Wafer

Claims (12)

  1. 　紫外光を吸収して媒質の屈折率を変化させるドーパントを含有するコアと該コアの周囲に形成されたクラッドとを備える光導波路回路の該コアに紫外光を照射する紫外光照射工程と、
    　前記ドーパントからの発光量を測定する発光量測定工程と、
    　を含み、前記測定した発光量の積算値に基づいて前記光導波路回路の特性を調整することを特徴とする光導波路回路の製造方法。     An ultraviolet light irradiation step of irradiating the core of the optical waveguide circuit comprising a core containing a dopant that absorbs ultraviolet light and changes a refractive index of the medium and a clad formed around the core;
    A light emission amount measuring step for measuring light emission amount from the dopant;
    And adjusting the characteristics of the optical waveguide circuit based on the integrated value of the measured light emission amount.
  2. 　前記測定した発光量の積算値が所定値に到達したときに前記紫外光の照射を停止することを特徴とする請求項１に記載の光導波路回路の製造方法。 2. The method of manufacturing an optical waveguide circuit according to claim 1, wherein the irradiation of the ultraviolet light is stopped when the integrated value of the measured light emission amounts reaches a predetermined value.
  3. 　前記ドーパントはゲルマニウムであることを特徴とする請求項１または２に記載の光導波路回路の製造方法。 3. The method of manufacturing an optical waveguide circuit according to claim 1, wherein the dopant is germanium.
  4. 　前記紫外光の波長は波長１９３ｎｍであることを特徴とする請求項３に記載の光導波路回路の製造方法。 4. The method of manufacturing an optical waveguide circuit according to claim 3, wherein the wavelength of the ultraviolet light is 193 nm.
  5. 　前記紫外光の波長は波長２４８ｎｍであることを特徴とする請求項３に記載の光導波路回路の製造方法。 4. The method of manufacturing an optical waveguide circuit according to claim 3, wherein the wavelength of the ultraviolet light is 248 nm.
  6. 　前記光導波路のクラッドはホウ素またはリンを含有することを特徴とする請求項３～５のいずれか一つに記載の光導波路回路の製造方法。 6. The method for manufacturing an optical waveguide circuit according to claim 3, wherein the cladding of the optical waveguide contains boron or phosphorus.
  7. 　紫外光を吸収して媒質の屈折率を変化させるドーパントを含有するコアと該コアの周囲に形成されたクラッドとを備える光導波路回路の該コアに紫外光を照射する紫外光源と、
    　前記ドーパントからの発光量を測定する発光量測定器と、
    　を備え、前記測定した発光量の積算値に基づいて前記光導波路回路の特性を調整することを特徴とする光導波路回路の製造装置。     An ultraviolet light source that irradiates the core of the optical waveguide circuit comprising a core containing a dopant that absorbs ultraviolet light and changes a refractive index of the medium, and a cladding formed around the core;
    A luminescence measuring device for measuring the luminescence from the dopant;
    And adjusting the characteristic of the optical waveguide circuit based on the integrated value of the measured light emission amount.
  8. 　前記測定した発光量の積算値が所定値に到達したときに前記紫外光の照射を停止する制御器を備えることを特徴とする請求項７に記載の光導波路回路の製造装置。 The apparatus for manufacturing an optical waveguide circuit according to claim 7, further comprising a controller that stops the irradiation of the ultraviolet light when the integrated value of the measured light emission amount reaches a predetermined value.
  9. 　前記ドーパントはゲルマニウムであることを特徴とする請求項７または８に記載の光導波路回路の製造装置。 9. The optical waveguide circuit manufacturing apparatus according to claim 7, wherein the dopant is germanium.
  10. 　前記紫外光の波長は波長１９３ｎｍであることを特徴とする請求項９に記載の光導波路回路の製造装置。 10. The apparatus for manufacturing an optical waveguide circuit according to claim 9, wherein the wavelength of the ultraviolet light is 193 nm.
  11. 　前記紫外光の波長は波長２４８ｎｍであることを特徴とする請求項９に記載の光導波路回路の製造装置。 10. The apparatus for manufacturing an optical waveguide circuit according to claim 9, wherein the wavelength of the ultraviolet light is 248 nm.
  12. 　前記光導波路のクラッドはホウ素またはリンを含有することを特徴とする請求項９～１１のいずれか一つに記載の光導波路回路の製造装置。 12. The apparatus for manufacturing an optical waveguide circuit according to claim 9, wherein the clad of the optical waveguide contains boron or phosphorus.
PCT/JP2012/064580 2011-08-02 2012-06-06 Method for manufacturing and device for manufacturing optical waveguide circuit WO2013018432A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011169408A JP5203491B2 (en) 2011-08-02 2011-08-02 Method and apparatus for manufacturing optical waveguide circuit
JP2011-169408 2011-08-02

Publications (1)

Publication Number Publication Date
WO2013018432A1 true WO2013018432A1 (en) 2013-02-07

Family

ID=47628972

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2012/064580 WO2013018432A1 (en) 2011-08-02 2012-06-06 Method for manufacturing and device for manufacturing optical waveguide circuit

Country Status (2)

Country Link
JP (1) JP5203491B2 (en)
WO (1) WO2013018432A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115480347A (en) * 2021-06-15 2022-12-16 中国科学院长春光学精密机械与物理研究所 Method for improving verticality of array waveguide fiber and slab waveguide in wavelength division multiplexer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6228509B2 (en) * 2014-05-19 2017-11-08 日本電信電話株式会社 Method for manufacturing wavelength conversion element
JP7302946B2 (en) * 2018-03-13 2023-07-04 富士通オプティカルコンポーネンツ株式会社 Optical device and optical communication module using the same

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001074950A (en) * 1999-08-31 2001-03-23 Hitachi Cable Ltd Method for adjusting characteristic for optical multiplexer/demultiplexer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001074950A (en) * 1999-08-31 2001-03-23 Hitachi Cable Ltd Method for adjusting characteristic for optical multiplexer/demultiplexer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115480347A (en) * 2021-06-15 2022-12-16 中国科学院长春光学精密机械与物理研究所 Method for improving verticality of array waveguide fiber and slab waveguide in wavelength division multiplexer

Also Published As

Publication number Publication date
JP5203491B2 (en) 2013-06-05
JP2013033150A (en) 2013-02-14

Similar Documents

Publication Publication Date Title
US6442311B1 (en) Optical device having modified transmission characteristics by localized thermal treatment
JP4414344B2 (en) Fabrication of waveguides and Bragg gratings by UV radiation
US6768850B2 (en) Method of index trimming a waveguide and apparatus formed of the same
Abe et al. 1-GHz-spaced 16-channel arrayed-waveguide grating for a wavelength reference standard in DWDM network systems
JP2001311847A (en) Method and device for correcting refractive index, and optical waveguide device
JP5203491B2 (en) Method and apparatus for manufacturing optical waveguide circuit
US7496256B2 (en) Diffraction grating and dispersion compensation circuit
WO2000011509A1 (en) Apparatus for manufacturing long-period fiber gratings and apparatus for manufacturing two-band long-period fiber gratings using the same
Amorim et al. Monolithic add–drop multiplexers in fused silica fabricated by femtosecond laser direct writing
Song et al. Bragg grating-assisted WDM filter for integrated optical triplexer transceivers
US6870967B2 (en) Pretrimming of tunable finite response (FIR) filter
WO2020031751A1 (en) Method for adjusting transmitted wavelength of signal light transmitted through optical waveguide device
JP2005055508A (en) Method and device for manufacturing grating type optical components, and optical components produced using the method and device
JP2005338467A (en) Optical branching device and manufacturing method therefor
JP2001074950A (en) Method for adjusting characteristic for optical multiplexer/demultiplexer
KR20100118295A (en) Writing optical fibergratings apparatus for laser
JP2001194549A (en) Method for controlling double refractivity in optical waveguide device optical waveguide device and grating device
JP2005195754A (en) Method of manufacturing optical waveguide, and the optical waveguide
JP3114698B2 (en) Array waveguide grating
Kobayashi et al. Direct fabrication of polyimide waveguide grating by synchrotron radiation
CN114217489A (en) Method and device for realizing refractive index modulation of optical device
JP2003315581A (en) Optical waveguide, multiwavelength light source and wavelength variable light source
Wosinski et al. Grating-assisted add-drop multiplexer realized in silica-on-silicon technology
JP3984187B2 (en) Manufacturing method of optical attenuator
Haque et al. Chemical-assisted femtosecond laser structuring of waveguide-embedded wavefront-splitting interferometers

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12819712

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12819712

Country of ref document: EP

Kind code of ref document: A1