Light-emitting device and optical fiber

1. A light-emitting device comprising:

an optical fiber including a light incident portion, a light emerging portion, and a wavelength converting portion, the wavelength converting portion being provided between the light incident portion and the light emerging portion and containing a wavelength converting material, the wavelength converting material being configured to be excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light, the wavelength converting material being configured to amplify the spontaneous emission of light to produce an amplified spontaneous emission of light;

a first light source unit configured to emit the excitation light to the light incident portion; and

a second light source unit configured to emit seed light to the light incident portion, the seed light being light for causing a stimulated emission of light to be produced from the wavelength converting material that has been excited by either the excitation light or the amplified spontaneous emission of light, wherein:

the seed light is formed by a plurality of seed light rays, having mutually different wavelengths and the plurality of seed light rays are incident on the light incident portion,

a wavelength of the excitation light falls within the range from 440 to 450 nm, and

the wavelength converting material contains Pr 3+ and Tb 3+ .

2. The light-emitting device of claim 1 , wherein

the second light source unit includes a plurality of light sources configured to emit the plurality of seed light rays, respectively.

3. The light-emitting device of claim 2 , further comprising a control member configured to control respective intensities of the plurality of seed light rays.

4. The light-emitting device of claim 1 , wherein

the light incident portion includes a reflection reducing portion configured to reduce reflection of the excitation light and the seed light.

5. The light-emitting device of claim 1 , wherein

the light emerging portion has a tilted surface tilted by a predetermined angle with respect to a plane intersecting at right angles with an optical axis of the optical fiber.

6. The light-emitting device of claim 1 , wherein

the light emerging portion includes a reflection reducing portion configured to reduce reflection of the excitation light and the stimulated emission of light.

7. The light-emitting device of claim 1 , wherein

the first light source unit includes a laser light source.

8. A light-emitting device comprising:

an optical fiber including a light incident portion, a light emerging portion, and a wavelength converting portion, the wavelength converting portion being provided between the light incident portion and the light emerging portion and containing a wavelength converting material, the wavelength converting material being configured to be excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light, the wavelength converting material being configured to amplify the spontaneous emission of light to produce an amplified spontaneous emission of light;

a first light source unit being configured to emit the excitation light to the light incident portion; and

a second light source unit being configured to emit seed light to the light incident portion, the seed light being light for causing a stimulated emission of light to be produced from the wavelength converting material that has been excited by either the excitation light or the amplified spontaneous emission of light, wherein:

the seed light is formed by a plurality of seed light rays, having mutually different wavelengths and the plurality of seed light rays are incident on the light incident portion, and

the first light source unit and the second light source unit each include:

a white light source; and

a spectroscopic grating configured to allow the excitation light and the plurality of seed light rays to emerge from the spectroscopic grating by separating light emitted from the white light source into multiple components of the light.

9. An optical fiber comprising:

a light incident portion;

a light emerging portion; and

a wavelength converting portion provided between the light incident portion and the light emerging portion and containing a wavelength converting material, the wavelength converting material being configured to be excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light, the wavelength converting material being configured to amplify the spontaneous emission of light to produce an amplified spontaneous emission of light, wherein:

the wavelength converting material is configured such that seed light incident on the light incident portion causes a stimulated emission of light from the wavelength converting material that has been excited by either the excitation light or the amplified spontaneous emission of light,

the seed light is formed by a plurality of seed light rays having mutually different wavelengths and the plurality of seed light rays are incident on the light incident portion, and

the wavelength converting material contains Pr 3+ and Tb 3+ .

10. The optical fiber of claim 9 , wherein

the light incident portion includes:

a first light incident portion on which the excitation light is incident; and

a second light incident portion which is provided separately from the first light incident portion and on which the seed light is incident.