Optical component manufacturing method, and optical component

An optical component manufacturing method, comprising:

• preparing a glass member in which a continuous refractive index changing region is to be provided,
• irradiating femtosecond laser light onto the glass member so as to condense it within the glass member, and
• moving a position of a condensed point of the femtosecond laser light relative to the glass member along a scanning direction, wherein:
• the femtosecond laser light has an energy amount that causes a light-induced refractive index change in the glass member,
• a light intensity distribution of the femtosecond laser light on a plane including the condensed point and orthogonal to a thickness direction of the glass member has a flat-top region,
• a beam irradiation region on the plane including the condensed point and orthogonal to the thickness direction of the glass member is a beam spot of the femtosecond laser light and is a single continuous region defined by a contour of a region where a light intensity in the light intensity distribution is 1/e2 or more of a maximum light intensity,
• the flat-top region is a region of ½ or more of the maximum light intensity,
• an area of the flat-top region is 0.45 times or more that of the beam irradiation region,
• an angle between a direction in which a width of the beam irradiation region is widest and a scanning direction is 70° or more and 110° or less, and
• an angle between the scanning direction and the plane orthogonal to the thickness direction of the glass member is 20° or less, and
• the beam spot is formed by
• (i) a first optical system including an aspherical lens, or
• (ii) a second optical system including a condenser lens and a cylindrical lens configured so that the femtosecond laser light passes through the condenser lens prior to passing through the cylindrical lens.