Light source device and projection display apparatus

A light source device comprising:

• a light source unit that emits linearly polarized light in a first wavelength range, the linearly polarized light including first light that is light in a first polarization direction and second light that is light in a second polarization direction orthogonal to the first polarization direction;
• a polarization separation element that receives the first light and the second light emitted from the light source unit;
• a phosphor that receives the first light transmitted through the polarization separation element;
• and
• a phase conversion element that receives the second light reflected by the polarization separation element,
• wherein
• the polarization separation element has a polarization transmission wavelength region including the first wavelength range, transmits the light in the first polarization direction and reflects the light in the second polarization direction in the polarization transmission wavelength region, and reflects light regardless of a polarization direction in a visible light range on a longer wavelength side than the polarization transmission wavelength region,
• the phosphor converts the received first light into third light in a wavelength range on a longer wavelength side than the polarization transmission wavelength region and emits the third light to the polarization separation element,
• the phase conversion element phase-converts the received second light into fourth light that is the light in the first polarization direction in the first wavelength range and emits the fourth light to the polarization separation element, and
• the polarization separation element combines illumination light with the third light reflected by the polarization separation element and the fourth light transmitted through the polarization separation element.