BACKGROUND ART

1. Technical Field

The present invention relates to a pulsed light generation device, a pulsed light generation method, an exposure apparatus having the pulsed light generation device and an inspection apparatus having the pulsed light generation device.

2. Description of Related Art

When using pulsed light emitted from a laser such as a semiconductor laser as a light source for an inspection apparatus or a processing apparatus, it is required to emit pulsed light with high intensity and narrow wavelength spectral width. In order to obtain pulsed light with high intensity, it is necessary to amplify pulsed light having been emitted from a semiconductor laser by an optical fiber amplifier. However, phase modulation occurs in the pulsed light through self-phase modulation while it is being amplified, resulting in broadening of the pulsed light wavelength spectrum.

Japanese Laid Open Patent Publication No. H8-125605 discloses an optical communication system used for signal light communication, in which signal light achieved by multiplexing signal light that has undergone intensity modulation executed in correspondence to binary signal data, and inverted signal light that has undergone intensity modulation executed in correspondence to an inverted binary signal generated by inverting the binary signal data, is transmitted through an optical fiber transmission path.

SUMMARY

The optical communication system disclosed in Japanese Laid Open Patent Publication No. H8-125605 comes up short in that the pulsed light cannot be amplified to achieve a high level of intensity while suppressing any broadening of the wavelength spectrum.

According to the first aspect of the present invention, a pulsed light generation device comprises: a first optical fiber through which first pulsed light and second pulsed light, having an intensity that decreases while an intensity of the first pulsed light increases, and increases while the intensity of the first pulsed light decreases, having been multiplexed and entered therein, are propagated; and a second optical fiber at which the first pulsed light, having exited the first optical fiber and entered therein, is amplified while being propagated therein, wherein: at the first optical fiber, phase modulation occurs in the first pulsed light due to cross phase modulation caused by the second pulsed light; and self-phase modulation occurring in the first pulsed light at the second optical fiber is diminished by the phase modulation having occurred at the first optical fiber.

According to the second aspect of the present invention, a pulsed light generation method comprises steps of: multiplexing first pulsed light and second pulsed light, having an intensity that decreases while an intensity of the first pulsed light increases, and increases while the intensity of the first pulsed light decreases, and causing the multiplexed first pulsed light and second pulsed light to enter a first optical fiber to be propagated therein; causing the first pulsed light, having exited the first optical fiber, to enter a second optical fiber and amplifying the first pulsed light as the first pulsed light is propagated through the second optical fiber; and diminishing phase modulation occurring in the first pulsed light at the second optical fiber, attributable to self-phase modulation, with phase modulation occurring in the first pulsed light at the first optical fiber, attributable to cross phase modulation caused by the second pulsed light.

