Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A micrometre-scale Raman silicon laser with a microwatt threshold


The application of novel technologies to silicon electronics has been intensively studied with a view to overcoming the physical limitations of Moore’s law, that is, the observation that the number of components on integrated chips tends to double every two years. For example, silicon devices have enormous potential for photonic integrated circuits on chips compatible with complementary metal–oxide–semiconductor devices, with various key elements having been demonstrated in the past decade1,2,3,4,5,6. In particular, a focus on the exploitation of the Raman effect has added active optical functionality to pure silicon7,8,9,10, culminating in the realization of a continuous-wave all-silicon laser11. This achievement is an important step towards silicon photonics, but the desired miniaturization to micrometre dimensions and the reduction of the threshold for laser action to microwatt powers have yet to be achieved: such lasers remain limited to centimetre-sized cavities with thresholds higher than 20 milliwatts12, even with the assistance of reverse-biased p–i–n diodes. Here we demonstrate a continuous-wave Raman silicon laser using a photonic-crystal, high-quality-factor nanocavity without any p–i–n diodes, yielding a device with a cavity size of less than 10 micrometres and an unprecedentedly low lasing threshold of 1 microwatt. Our nanocavity design exploits the principle that the strength of light–matter interactions is proportional to the ratio of quality factor to the cavity volume and allows drastic enhancement of the Raman gain beyond that predicted theoretically13,14. Such a device may make it possible to construct practical silicon lasers and amplifiers for large-scale integration in photonic circuits.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Structure of Raman silicon laser based on a heterostructure nanocavity.
Figure 2: Configuration of nanocavity Raman silicon laser.
Figure 3: Optical measurements on fabricated nanocavities.
Figure 4: Continuous-wave operation of fabricated nanocavity Raman silicon laser.


  1. Liu, A. et al. A high-speed silicon optical modulator based on a metal–oxide–semiconductor capacitor. Nature 427, 615–618 (2004)

    CAS  ADS  Article  Google Scholar 

  2. Jalali, B. & Fathpour, S. Silicon photonics. J. Lightwave Technol. 24, 4600–4615 (2006)

    CAS  ADS  Article  Google Scholar 

  3. Barkai, A. et al. Integrated silicon photonics for optical networks. J. Opt. Netw. 6, 25–47 (2007)

    Article  Google Scholar 

  4. Fang, A. W. et al. Hybrid silicon evanescent devices. Mater. Today 10, 28–35 (2007)

    CAS  Article  Google Scholar 

  5. Won, R. Integrating silicon photonics. Nature Photon. 4, 498–499 (2010)

    Article  Google Scholar 

  6. Michel, J., Liu, J. & Kimerling, L. C. High-performance Ge-on-Si photodetectors. Nature Photon. 4, 527–534 (2010)

    CAS  ADS  Article  Google Scholar 

  7. Claps, R., Dimitropoulos, D., Han, Y. & Jalali, B. Observation of Raman emission in silicon waveguides at 1.54 μm. Opt. Express 10, 1305–1313 (2002)

    CAS  ADS  Article  Google Scholar 

  8. Claps, R., Dimitropoulos, D., Raghunathan, V., Han, Y. & Jalali, B. Observation of stimulated Raman amplification in silicon waveguides. Opt. Express 11, 1731–1739 (2003)

    CAS  ADS  Article  Google Scholar 

  9. Boyraz, O. & Jalali, B. Demonstration of a silicon Raman laser. Opt. Express 12, 5269–5273 (2004)

    CAS  ADS  Article  Google Scholar 

  10. Rong, H. et al. An all-silicon Raman laser. Nature 433, 292–294 (2005)

    CAS  ADS  Article  Google Scholar 

  11. Rong, H. et al. A continuous-wave Raman silicon laser. Nature 433, 725–728 (2005)

    CAS  ADS  Article  Google Scholar 

  12. Rong, H. et al. Low-threshold continuous-wave Raman silicon laser. Nature Photon. 1, 232–237 (2007)

    CAS  ADS  Article  Google Scholar 

  13. Yang, X. & Wong, C. W. Design of photonic band gap nanocavities for stimulated Raman amplification and lasing in monolithic silicon. Opt. Express 13, 4723–4730 (2005)

    CAS  ADS  Article  Google Scholar 

  14. Yang, X. & Wong, C. W. Coupled-mode theory for stimulated Raman scattering in high-Q/V m silicon photonic band gap defect cavity lasers. Opt. Express 15, 4763–4780 (2007)

    CAS  ADS  Article  Google Scholar 

  15. Loudon, R. The Raman effect in crystals. Adv. Phys. 13, 423–482 (1964)

    CAS  ADS  Article  Google Scholar 

  16. Ralston, J. M. & Chang, R. K. Spontaneous-Raman-scattering efficiency and stimulated scattering in silicon. Phys. Rev. B 2, 1858–1862 (1970)

    ADS  Article  Google Scholar 

  17. Liang, T. K. & Tsang, H. K. Role of free carriers from two-photon absorption in Raman amplification in silicon-on-insulator waveguides. Appl. Phys. Lett. 84, 2745–2747 (2004)

    CAS  ADS  Article  Google Scholar 

  18. Claps, R., Raghunathan, V., Dimitropoulos, D. & Jalali, B. Influence of nonlinear absorption on Raman amplification in silicon waveguides. Opt. Express 12, 2774–2780 (2004)

    CAS  ADS  Article  Google Scholar 

  19. Noda, S., Chutinan, A. & Imada, M. Trapping and emission of photons by a single defect in a photonic bandgap structure. Nature 407, 608–610 (2000)

    CAS  ADS  Article  Google Scholar 

  20. Akahane, Y., Asano, T., Song, B. S. & Noda, S. High-Q photonic nanocavity in a two-dimensional photonic crystal. Nature 425, 944–947 (2003)

    CAS  ADS  Article  Google Scholar 

  21. Song, B. S., Noda, S., Asano, T. & Akahane, Y. Ultra-high-Q photonic double-heterostructure nanocavity. Nature Mater. 4, 207–210 (2005)

    CAS  ADS  Article  Google Scholar 

  22. Takahashi, Y. et al. Design and demonstration of high-Q photonic heterostructure nanocavities suitable for integration. Opt. Express 17, 18093–18102 (2009)

    CAS  ADS  Article  Google Scholar 

  23. Taguchi, Y., Takahashi, Y., Sato, Y., Asano, T. & Noda, S. Statistical studies of photonic heterostructure nanocavities with an average Q factor of three million. Opt. Express 19, 11916–11921 (2011)

    CAS  ADS  Article  Google Scholar 

  24. Takano, H., Asano, T. & Noda, S. at Spring Meeting Jpn Soc. Appl. Phys., abstr. 29a-ZB-8. (2007)

  25. Terawaki, R., Takahashi, Y., Chihara, M., Inui, Y. & Noda, S. Ultrahigh-Q photonic crystal nanocavities in wide optical telecommunication bands. Opt. Express 20, 22743–22752 (2012)

    CAS  ADS  Article  Google Scholar 

  26. Song, B. S., Jeon, S. B. & Noda, S. Symmetrically glass-clad photonic crystal nanocavities with ultrahigh quality factors. Opt. Lett. 36, 91–93 (2011)

    CAS  ADS  Article  Google Scholar 

  27. Han, Z., Checoury, X., Haret, L.-D. & Boucaud, P. High quality factor in a two-dimensional photonic crystal cavity on silicon-on-insulator. Opt. Lett. 36, 1749–1751 (2011)

    CAS  ADS  Article  Google Scholar 

  28. Baba, T. Slow light in photonic crystals. Nature Photon. 2, 465–473 (2008)

    CAS  ADS  Article  Google Scholar 

  29. Hagino, H., Takahashi, Y., Tanaka, Y., Asano, T. & Noda, S. Effects of fluctuation in air hole radii and positions on optical characteristics in photonic crystal heterostructure nanocavities. Phys. Rev. B 79, 085112 (2009)

    ADS  Article  Google Scholar 

  30. Asano, T., Song, B. S. & Noda, S. Analysis of the experimental Q factors (1 million) of photonic crystal nanocavities. Opt. Express 14, 1996–2002 (2006)

    ADS  Article  Google Scholar 

Download references


We especially thank H. Takano for a preliminary calculation done before the start of this project. We thank K. Ishizaki and K. Kitamura for assistance in device fabrication, Y. Tanaka for assistance with finite-difference time-domain calculations, A. Oskooi and H. Ishihara for comments, and Y. Sakamoto for software assistance. Y.T. is supported by the NanoSquare programme, Funds for the Development of Human Resources in Science and Technology, commissioned by MEXT. This work was supported by JST, PRESTO, the NanoSquare programme and MEXT KAKENHI (grant numbers 23104721 and 21104512). The spectral measurements were partly supported by JSPS KAKENHI (grant number 23686015) and the Asahi Grass Foundation. The device fabrication was greatly supported by JSPS KAKENHI (grant number 20226002), the Ministry of Economy, Trade and Industry (METI) through its ‘Future Pioneering Projects’, and the CPHoST programme.

Author information

Authors and Affiliations



Y.T. designed the project, designed the original device, fabricated the samples, performed the measurements and wrote the paper. S.N. organized the contribution to the project from Kyoto University, where the fundamental studies to realize high-Q/V nanocavities and the initial investigation into Raman lasers was performed. S.N. also contributed greatly to writing the paper. Y.I. analytically determined the optimum crystalline direction for lasing and contributed to writing Supplementary Information, sections A and B. M.C. established the method to tune the nanocavity mode spacing, T.A. contributed to the theoretical analysis and R.T. contributed to the development of the measurement system.

Corresponding authors

Correspondence to Yasushi Takahashi or Susumu Noda.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data parts A-F, which include a Supplementary Discussion and Equations, Supplementary Figures 1-6 and additional references. (PDF 445 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Takahashi, Y., Inui, Y., Chihara, M. et al. A micrometre-scale Raman silicon laser with a microwatt threshold. Nature 498, 470–474 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing