Phase-synchronous detection of coherent and incoherent nonlinear signals

Khadga Jung Karki, Loni Kringle, Andrew H. Marcus, Tõnu Pullerits

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The nonlinear optical response of a material system contains detailed information about its electronic structure. Standard approaches to nonlinear spectroscopy often use multiple beams crossed in a sample, and detect the wave vector matched polarization in transmission. Here, we apply a phase-synchronous digital detection scheme using an excitation geometry with two phase-modulated collinear ultrafast pulses. This scheme can be used to efficiently detect nonlinear coherent signals and incoherent signals, such as higher harmonics and multiphoton fluorescence and photocurrent, from various systems including a photocell device. We present theory and experiment to demonstrate that when the phase of each laser pulse is modulated at the frequency φ1 and φ2, respectively, nonlinear signals can be isolated at the frequencies n (φ21), where n = 0, 1, 2, ⋯. This approach holds promise for performing nonlinear spectroscopic measurements under low-signal conditions.

Original languageEnglish
Article number015504
JournalJournal of Optics (United Kingdom)
Issue number1
StatePublished - 20 Nov 2015
Externally publishedYes


  • nonlinear optics
  • phase-modulation
  • ultrafast optics


Dive into the research topics of 'Phase-synchronous detection of coherent and incoherent nonlinear signals'. Together they form a unique fingerprint.

Cite this