Direct writing of high-density nitrogen-vacancy centers inside diamond by femtosecond laser irradiation

Abstract

High-density nitrogen-vacancy (NV) centers exceeding 1016/cm3 inside a diamond can be achieved by femtosecond laser irradiation. The number of pulses and pulse energy were adjusted considering the increasing trend of the NV concentration and damage generation. The NV concentration first grew as the number of laser pulses was increased, and then the concentration was temporarily saturated or decreased. By increasing the number of laser pulses more than 2.5–5 × 107, the concentration increased again. The Hahn-echo measurement revealed that electron spins of the substitutional nitrogen center (P1) were dominant source for decoherence and the number of paramagnetic defects induced by the laser irradiation was not significant for degradation of spin coherence of the laser-induced NV centers even without a post-annealing process. Such high-dense ensemble NV centers are crucial for a high-sensitive quantum sensor.

Quantum Systems for Enhanced High Energy Particle Physics Detectors

“…The density of defects is one of the parameters that is actively being optimized as the sensitivity as a magnetometer scales with the square root of its number [117]. Several existing approaches using modified deposition schemes [118] or creation of defects with laser radiation [119] can achieve densities of 10 16-18 cm −3 . In spite of the possibility of locally enhancing this density by another two to three orders of magnitude through hyperpolarization [102] (polarizing the atoms surrounding the defects), an additional increase by two orders of magnitude in the defect abundance (or the size of the locally polarized region surrounding them) will nevertheless be required before such helicity trackers can be realistically contemplated.…”

Impact of Helium Ion Implantation Dose and Annealing on Dense Near-Surface Layers of NV Centers

“…Such electron irradiation produces a minimum of undesirable defects, but the large electron energies required to create vacancies limit the control of the depth; therefore, this method is good for fabricating sensors with uniform NV distribution, where the sensing volume matches the volume of the bulk diamond. In addition, laser writing [24,25], where impulse lasers are used to create the vacancies, is not convenient for the creation of NV layers over a wide area due to limited optical depth resolution and spatial inhomogeneity as well as due to relatively high optical power required per unit area. This makes it more suited for the creation of single NVs or micrometer-sized vacancy regions.…”

Impact of helium ion implantation dose and annealing on dense near-surface layers of NV centers

“…Therefore, this method is good for fabrication of sensors with uniform NV distribution, where the sensing volume matches the volume of the bulk diamond. And laser writing [23,24], where impulse lasers are used to create the vacancies, is not convenient for creation of NV layers over a wide area due to limited optical depth resolution and spatial inhomogeneity as well as due to relatively high optical power required per unit area, leaving it more suited for creation of single NVs or micrometer sized vacancy regions.…”

“…In many applications is desirable to keep high spatial resolution by creating well localized NV ensembles [21,23,25,26], for example, thin NV layers for magnetic imaging [8,27,28]. In addition, dense NV ensembles are desirable since the sensitivity scales with square root of the number of NV − centers.…”