Pulsed light generation device and pulsed light generation method

Abstract

This pulsed light generation device comprises: an oscillation unit (1); a broadband-forming unit (2); a modulation unit (6) that is configured to include a polarization-maintaining fiber and that modulates pulsed light; and a polarization-changing unit (5) that changes the polarization direction of the pulsed light to a direction that intersects both the slow axis direction and the fast axis direction of the polarization-maintaining fiber. The modulation unit (6) uses a soliton self-frequency shift to modulate the wavelength of pulsed light (L), the polarization direction of which has been changed by the polarization-changing unit (5), and forms first pulsed light (L1) that is pulsed light in the polarization direction along the slow axis direction and second pulsed light (L2) that is pulsed light in the polarization direction along the fast axis direction.

Claims

1. A pulsed light generation device comprising: an oscillator that emits pulsed light; a broadbanding unit disposed downstream of the oscillator in the optical path of the pulsed light and broadening the spectrum of the pulsed light; a modulation unit disposed downstream of the broadbanding unit in the optical path of the pulsed light and comprising a polarization-maintaining fiber, which modulates the pulsed light; and a polarization-changing unit disposed upstream of the modulation unit in the optical path of the pulsed light and changing the polarization direction of the pulsed light in a direction that intersects both the slow axis direction and the fast axis direction of the polarization-maintaining fiber, wherein the modulation unit modulates the wavelength of the pulsed light whose polarization direction has been changed by the polarization-changing unit using soliton self-frequency shift, thereby forming a first pulsed light which is the pulsed light with a polarization direction along the slow axis direction and a second pulsed light which is the pulsed light with a polarization direction along the fast axis direction.

2. The pulsed light generation apparatus according to claim 1, further comprising a polarizer positioned downstream of the modulation section in the optical path of the pulsed light, which adjusts the intensity ratio between the first pulsed light and the second pulsed light.

3. The pulse light generation apparatus according to claim 1 or 2, wherein the polarization changing section is a half-wave plate.

4. A pulse light generation apparatus according to any one of claims 1 to 3, comprising an optical intensity control unit disposed between the oscillator and the modulation unit in the optical path of the pulse light, which controls the intensity of the pulse light for each pulse.

5. A pulse light generation apparatus according to any one of claims 1 to 4, comprising: a branching unit disposed downstream of the modulation unit in the optical path of the pulse light and branching the first pulse light and the second pulse light; another polarization changing unit disposed downstream of the branching unit in the optical path of the pulse light and changing at least one of the first polarization direction and the second polarization direction so that the first polarization direction, which is the polarization direction of the first pulse light, and the second polarization direction, which is the polarization direction of the second pulse light, coincide; and a sum frequency generating unit disposed downstream of the other polarization changing unit in the optical path of the pulse light and combining the first pulse light and the second pulse light, and emitting sum frequency light by sum frequency generation.

6. A pulse light generation apparatus according to any one of claims 1 to 5, comprising a time width compression unit arranged upstream of the modulation unit in the optical path of the pulse light, for compressing the time width of the pulse light.

7. A pulse light generation method comprising: an oscillation step of oscillating pulse light; a broadbanding step of broadening the spectrum of the pulse light oscillated in the oscillation step; a modulation step of modulating the pulse light after broadbanding in the broadbanding step using a modulation unit configured to include a polarization-maintaining fiber; and a polarization change step of changing the polarization direction of the pulse light before modulation in the modulation step to a direction intersecting both the slow axis direction and the fast axis direction of the polarization-maintaining fiber, wherein in the modulation step, the wavelength of the pulse light whose polarization direction has been changed in the polarization change step is modulated using a soliton self-frequency shift to form a first pulse light which is the pulse light with a polarization direction along the slow axis direction and a second pulse light which is the pulse light with a polarization direction along the fast axis direction.

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