Pulsed light generation device, pulsed light generation method, exposure apparatus having pulsed light generation device and inspection apparatus having pulsed light generation device

A pulsed light generation device, comprising:

• an optical coupler having at least four input/output ports including a first port, a second port, a third port and a fourth port;
• a connection optical path that connects the third port with the fourth port;
• and
• a phase modulation element disposed in the connection optical path, wherein:
• the optical coupler branches input pulsed light input to the first port and outputs the branched input pulsed light as first-direction pulsed light and second-direction pulsed light respectively to the third port and to the fourth port;
• and
• the phase modulation element applies phase modulation to at least either one of the first-direction pulsed light and the second-direction pulsed light, thereby outputs output pulsed lights through the first port and through the second port, wherein a waveform of one of the output pulsed lights output through the first port is different from a waveform of the other of the output pulsed lights output through the second port, wherein:
• in the optical coupler, light can be propagated between the first port and the third port, between the first port and the fourth port, between the second port and the third port and between the second port and the fourth port;
• a phase of the light propagated between the first port and the fourth port is delayed by ¼ of wavelength relative to the phase of the light propagated between the first port and the third port;
• and
• the phase of the light propagated between the second port and the third port is delayed by ¼ of wavelength relative to the phase of the light propagated between the second port and the fourth port.

A pulsed light generation method, comprising steps of:

• inputting pulsed light for inputting to a first port of an optical coupler having at least four input/output ports including the first port, a second port, a third port and a fourth port, and branching the pulsed light for inputting;
• outputting first-direction pulsed light and second-direction pulsed light respectively through the third port and the fourth port, to a connection optical path to which the third port and the fourth port are connected in a loop;
• applying phase modulation to at least either one of the first-direction pulsed light and the second-direction pulsed light in the connection optical path;
• and
• outputting output pulsed lights through the first port and through the second port, wherein:
• a waveform of the either of the output pulsed lights through the first port is different from a waveform of the other of the output pulsed lights output through the second port.