Corcoran, B. et al. Ultra-dense optical data transmission over standard fibre with a single chip source. Nat. Commun. 11, 2568 (2020). Opačak, N. & Schwarz, B. Theory of frequency-modulated combs in lasers with spatial hole burning, dispersion, and Kerr nonlinearity. Phys. Rev. Lett. 123, 243902 (2019). Jin, W. et al. Hertz-linewidth semiconductor lasers using CMOS-ready ultra-high- Q microresonators. Nat. Photon. 15, 346–353 (2021).

First remove the clipper guard. Slide the comb into the hair at whatever angle you desire. It doesn’t have to be a perfect box style cut. wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 13 people, some anonymous, worked to edit and improve it over time.

Chang, L., Liu, S. T. & Bowers, J. E. Integrated optical frequency comb technologies. Nat. Photon. 16, 95–108 (2022). Flattopper I with flat comb teeth allows a very precise and especially straight cut with the hair clipper Terra, O. Absolute frequency measurement of the hyperfine structure of the 5S 1/2–5D 3/2 two-photon transition in rubidium using femtosecond frequency comb. Measurement 144, 83–87 (2019).

As long as you’ve got a decent clipper, the only other items you’ll need are a good pair of scissors and a Topper Comb.

Liang, D. et al. An energy-efficient and bandwidth-scalable DWDM heterogeneous silicon photonics integration platform. IEEE J. Sel. Top. Quant. Electron. 28, 6100819 (2022). Shang, C. et al. Electrically pumped quantum-dot lasers grown on 300mm patterned Si photonic wafers. Light Sci. Appl. 11, 299 (2022). This is not a style you can easily achieve yourself, and I suggest you don’t try! However it is fairly straight forward to do. Different Techniques

Nielsen, D. & Chuang, S. L. Four-wave mixing and wavelength conversion in quantum dots. Phys. Rev. B 81, 035305 (2010). The next step is to cut the top of the head. It is important that the person’s head is upright and facing forward. A number 2 or 3 is usually the preferred length, although you could go even shorter if you wanted a more dramatic look. Step 3 Schwarz, B. et al. Monolithic frequency comb platform based on interband cascade lasers and detectors. Optica 6, 890–895 (2019). De Cea, M., Atabaki, A. H. & Ram, R. J. Power handling of silicon microring modulators. Opt. Express 27, 24274–24285 (2019).Slide the comb onto the top of the head and lift it until you reach the desired length. Ensure you have the comb level and then cut the hair with your clippers. Bardella, P., Columbo, L. L. & Gioannini, M. Self-generation of optical frequency comb in single section quantum dot Fabry-Perot lasers: a theoretical study. Opt. Express 25, 26234–26252 (2017).