Nonlinear optical spectrum of diamond at femtosecond regime

Abstract

Although diamond photonics has driven considerable interest and useful applications, as shown in frequency generation devices and single photon emitters, fundamental studies on the third-order optical nonlinearities of diamond are still scarce, stalling the development of an integrated platform for nonlinear and quantum optics. The purpose of this paper is to contribute to those studies by measuring the spectra of two-photon absorption coefficient (β) and the nonlinear index of refraction (n2) of diamond using femtosecond laser pulses, in a wide spectral range. These measurements show the magnitude of β increasing from 0.07 to 0.23 cm/GW, as it approaches the bandgap energy, in the region from 3.18 to 4.77 eV (390–260 nm), whereas the n2 varies from zero to 1.7 × 10−19 m2/W in the full measured range, from 0.83–4.77 eV (1500–260 nm). The experimental results are compared with theoretical models for nonlinear absorption and refraction in indirect gap semiconductors, indicating the two-photon absorption as the dominant effect in the dispersion of the third-order nonlinear susceptibility. These data, together with optical Kerr gate measurements, also provided here, are of foremost relevance to the understanding of ultrafast optical processes in diamond and its nonlinear optical properties.

Giant nonlinear optical effects induced by nitrogen-vacancy centers in diamond crystals

“…Hereafter, we will discuss the value of n 2 to examine the effect of the NV center in diamond. The n 2 in Table 2 obtained for the non-implanted and the lightly implanted diamond (2.0×10 11 N + /cm 2 ) are very small if we consider the standard deviations, but are in good agreement with those obtained by Z-scan measurements by other groups [13,29]. On the other hand, the quadratic dependence of the ∆R R signal observed in the present study is surprisingly coincide with the signal from photo-carriers generated upon green laser (532 nm) illumination as the function of the green laser power [30].…”

Diamond studies for applications in quantum technologies

“…Therefore, considering the interests on diamond nonlinear photonics, this work presents measurements of third-order optical nonlinearities in type IIa diamond, performed over a broad spectral range, from 0.83 -4.77 eV (1500 -260 nm), at femtosecond regime. (22) To the best of our knowledge, this is the first report of such a wide range of nonlinear optical properties in diamond, particularly for nonlinear refraction and absorption. The measurements that were obtained by Z-scan technique are compared to theoretical prediction for indirect gap semiconductors, which is based on phonon-assisted two-photon absorption (111)(112)(113).…”

“…The study and parts of the text in this chapter have been published in ref. (22). Here we expand on that discussion, offering more context on the subject and including a brief review on relevant topics of nonlinear optics and more details on the experimental setup.…”

“…Finally, in Chapter 8 we studied nonlinear properties of diamond, conducting a study of its nonlinear refraction index in a wide spectral range. 22 We also discuss the technique known as z-scan, a versatile and relatively simple method used to obtain nonlinear properties with good precision. The studies described in Chapters 6 and 7 were developed in close collaboration with the Photonics Group, benefiting greatly from the knowledge and experience of Dr. Juliana Almeida and Prof. Cleber Mendonça.…”

“…Open and closed Z-scan signatures at 3.54 eV (350 nm) (a and b, respectively) and 2.21 eV (560 nm)(c and d, respectively). The inset in (a) and (b) displays the linear dependence on the transmittance change (∆T) with the intensity at 3.54 eV (350 nm), whose slopes are approximately 1 in the log-log plot.Source: ALMEIDA; ONCEBAY(22) …”