Measuring phonon dephasing with ultrafast pulses using Raman spectral interference

Abstract

A technique to measure the decoherence time of optical phonons in a solid is presented. Phonons are excited with a pair of time-delayed 80 fs near infrared pulses via spontaneous transient Raman scattering. The spectral fringe visibility of the resulting Raman pulse pair, as a function of time delay, is used to measure the phonon dephasing time. The method avoids the need to use either narrow band or few femtosecond pulses and is useful for low phonon excitations. The dephasing time of phonons created in bulk diamond is measured to be = 6.8 ps ͑⌬ = 1.56 cm −1 ͒.

Preparation and Decay of a Single Quantum of Vibration at Ambient Conditions

“…ASjS in Eq. (8). More precisely, if the detection efficiency of the herald mode a S is 0 < η ≤ 1 (which we model as a beam splitter with transmittance η placed before the detector), we find (see Supplemental Material, Sec.…”

“…The most popular is time-resolved coherent anti-Stokes Raman scattering, where a large coherent phonon population is excited by a pair of laser pulses and is probed by a delayed pulse [7]. Another technique-transient coherent ultrafast phonon spectroscopy-uses the interference of the Stokes photons from the spontaneous Raman scattering of two coherent pumps to determine the decoherence of the vibrational mode [8,9]. While these techniques reveal the timescales over which the vibration decays or loses its phase coherence, observing single quanta of the vibration itself has proved far more elusive.…”

Efficient diamond Raman laser generating 65 fs pulses

“…However, SPM continues to increase as the pulse duration is reduced, and so for sufficiently short pulses, we expect SPM to become significant. For diamond, we have 2 T = 6.8 ps [15], and so with our <200 fs pump pulses, we are in the strongly-transient regime. As an illustration, in direct comparison with the picosecond Raman laser in [10], the present highly-transient femtosecond Raman laser has a similar Raman threshold in terms of pump pulse energy (tens of nanojoules), despite having more than an order of magnitude shorter pulse duration and so significantly higher peak intensity.…”

High‐order Stokes and anti‐Stokes Raman generation in monoisotopic CVD 12C‐diamond

“… a) Diamond, similarly to other carbon forms having the natural composition ( nat C), contains the isotopic mixture of 98.93% 12 C and 1.07% 13 C. b) The value is estimated from the linewidth (Δ ν R ) in the spontaneous Raman scattering spectrum as follows: T 2 ∼ ( π Δ ν R ) –1 . c) According to , T 2 ∼ 6.8 ps (Δ ν R ∼ 1.56 cm –1 ) for HPHT‐ diamond Ib‐type (HPHT is the high‐pressure/high‐temperature growth method). …”

“…c) According to , T 2 ∼ 6.8 ps (Δ ν R ∼ 1.56 cm –1 ) for HPHT‐ diamond Ib‐type (HPHT is the high‐pressure/high‐temperature growth method).…”