# University at Buffalo identifies optical fingerprints of 10 defects in h-BN via nonlinear modeling

- Published: 2026-11-07 05:42 UTC
- Section: Digital & Computing › Quantum technology
- Tags: hexagonal boron nitride, second harmonic generation, quantum photonics, University at Buffalo, atomic defects h-BN, nonlinear optical susceptibilities, single photon emitters
- URL: https://realtech.media/news/rt-b5473438903000d490a4441f_university_at_buffalo/

**First-principles simulations showed that atomic defects in hexagonal boron nitride increase second-harmonic generation by orders of magnitude.**

![University at Buffalo identifies optical fingerprints of 10 defects in h-BN via nonlinear modeling](https://realtech.media/media/2026/11/dca0c3567e11c8b3.jpg)
*Jan Pavelka, Wikimedia Commons, CC BY-SA 4.0*

A research team led by the University at Buffalo modeled the optical signatures of 10 known atomic defects in multilayer hexagonal boron nitride (h-BN), according to a study published in Nano Letters [1]. The researchers calculated polarization-resolved linear, second-order, and third-order optical susceptibilities to identify how specific lattice flaws interact with laser radiation. The findings provide a theoretical framework for optical identification and defect engineering in 2D materials intended for quantum photonics and sensing.

## Symmetry breaking and nonlinear response

While point defects altered the linear optical response only weakly, they led to significant amplification of nonlinear susceptibilities [1]. Carbon-based defect complexes broke local structural symmetry and introduced resonant transitions, driving orders-of-magnitude increases in second-harmonic generation (SHG) [1]. Third-harmonic generation was also amplified across the defect configurations, though it proved less sensitive to local atomic coordination than second-order processes [1].

Simulations included boron and nitrogen vacancies alongside carbon replacement complexes. The calculations revealed that nonlinear signatures vary sharply with defect geometry, even among structures with identical chemical compositions [1]. For instance, when evaluating two configurations of four-carbon defects, one structure generated intense nonlinear emission across two polarization directions, whereas the alternative geometry confined the strong optical response to a single polarization direction [1].

## Experimental verification

Measurements performed on carbon-doped h-BN samples qualitatively supported the calculated trends in nonlinear optical enhancement [1]. Because specific h-BN defects can operate as single-photon emitters, reliable nonlinear optical fingerprints allow researchers to map and classify active quantum centers non-destructively [1]. The authors reported that establishing these distinct optical signatures is an essential operational step toward designing deterministic defect arrays for quantum communication systems [1].

## Sources

1. [Nano Letters](https://doi.org/10.1021/acs.nanolett.6c03684)
2. [EurekAlert](https://www.eurekalert.org/news-releases/1150935)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-b5473438903000d490a4441f_university_at_buffalo/