Dispersion measuring device, and dispersion measuring method

A dispersion measuring device comprising:

• a light source configured to output a first optical pulse;
• a pulse converter including a spatial light modulator configured to present a phase pattern for generating modulated light by applying a predetermined phase shift for each wavelength to the first optical pulse, a light input end of the pulse converter is optically coupled to the light source and the pulse converter forming an optical pulse train from the first optical pulse, and the optical pulse train being the modulated light including a plurality of second optical pulses having a time difference from each other and having center wavelengths different from each other;
• a correlation optical system configured to receive the optical pulse train and output correlated light including a plurality of third optical pulses that are cross-correlation or autocorrelation of the optical pulse train;
• a dispersion medium having a positive or negative group delay dispersion and configured to receive the correlated light output from the correlation optical system, a light input end of the dispersion medium being optically coupled to a light output end of the correlation optical system and to give a group delay dispersion to the plurality of third optical pulses included in the correlated light to increase peak intensities of the plurality of third optical pulses to be equal to or greater than the detection threshold value;
• a detector configured to receive the correlated light transmitted through the dispersion medium and detect a temporal waveform of the correlated light having a peak intensity equal to or greater than a detection threshold value;
• and
• an arithmetic processor electrically connected to the detector, wherein
• a measurement object is disposed on an optical path between the pulse converter and the correlation optical system, a light input end of the measurement object being optically coupled to a light output end of the pulse converter and a light output end of the measurement object being optically coupled to a light input end of the correlation optical system,
• the arithmetic processor estimates a wavelength dispersion amount of the measurement object based on the temporal waveform of the correlated light,
• and
• the phase pattern presented by the spatial light modulator of the pulse converter includes a pattern for giving a group delay dispersion having a sign opposite to the group delay dispersion of the dispersion medium to the first optical pulse so that peak intensities of the plurality of third optical pluses in the time domain are reduced.

A dispersion measuring method comprising:

• outputting a first optical pulse;
• forming an optical pulse train from the first optical pulse, after outputting the first light pulse, the optical pulse train being modulated light including a plurality of second optical pulses having a time difference from each other and having center wavelengths different from each other, by using a spatial light modulator configured to present a phase pattern for generating the modulated light by applying a predetermined phase shift for each wavelength to the first optical pulse;
• transmitting the optical pulse train through a dispersion medium having a positive or negative group delay dispersion after forming the optical pulse train from the first light pulse and configured to give a group delay dispersion to the plurality of second optical pulses included in the optical pulse train to increase peak intensities of the plurality of second optical pulses to be equal to or greater than the detection threshold value, and transmitting the optical pulse train through a measurement object;
• receiving the optical pulse train transmitted through the dispersion medium, generating correlated light including a plurality of third optical pulses that are cross-correlation or autocorrelation of the optical pulse train, and detecting a temporal waveform of the correlated light formed from the optical pulse train having a peak intensity equal to or greater than a detection threshold value;
• and
• estimating a wavelength dispersion amount of the measurement object based on the temporal waveform of the correlated light, wherein
• the phase pattern presented by the spatial light modulator in forming the optical pulse train includes a pattern for giving a group delay dispersion having a sign opposite to the group delay dispersion of the dispersion medium to the first optical pulse.

A dispersion measuring method comprising:

• outputting a first optical pulse;
• forming an optical pulse train from the first optical pulse, after outputting the first light pulse, the optical pulse train being modulated light including a plurality of second optical pulses having a time difference from each other and having center wavelengths different from each other, by using a spatial light modulator configured to present a phase pattern for generating the modulated light by applying a predetermined phase shift for each wavelength to the first optical pulse;
• outputting correlated light including a plurality of third optical pulses that are cross-correlation or autocorrelation of the optical pulse train after the optical pulse train is formed from the first light pulse and is transmitted through a measurement object;
• transmitting the correlated light through a dispersion medium having a positive or negative group delay dispersion and configured to give a group delay dispersion to the plurality of third optical pulses included in the correlated light so that intensities of the plurality of third optical pulses are increased to be equal to or greater than the detection threshold value;
• detecting a temporal waveform of the correlated light transmitted through the dispersion medium;
• and
• estimating a wavelength dispersion amount of the measurement object based on the temporal waveform of the correlated light, wherein
• in the detecting, the temporal waveform of the correlated light having an intensity equal to or greater than a detection threshold value is detected,
• the phase pattern presented by the spatial light modulator in forming the optical pulse train includes a pattern for giving a group delay dispersion having a sign opposite to the group delay dispersion of the dispersion medium to the first optical pulse.