Narrow-Linewidth Lasers on a Silicon Chip

  • Edward H. Bernhardi
  • Markus Pollnau
Conference paper
Part of the NATO Science for Peace and Security Series B: Physics and Biophysics book series (NAPSB)


Diode-pumped distributed-feedback (DFB) channel waveguide lasers were demonstrated in Erˆ3+-doped and Ybˆ3+-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99 %. Monolithic DFB cavities with Q-factors of up to 1. 35 × 106 were realized. The Erˆ3+-doped DFB laser delivered 3 mW of output power with a slope efficiency of 41 % versus absorbed pump power. Single-longitudinal-mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1. 70 ± 0. 58 kHz, corresponding to a laser Q-factor of 1. 14 × 1011. Yb3+-doped DFB lasers were demonstrated at wavelengths near 1,020 nm with output powers of 55 mW and a slope efficiency of 67 % versus launched pump power. An Ybˆ3+-doped dual-wavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at \(\sim 15\,\mathrm{GHz}\) with a –3-dB width of 9 kHz and a long-term frequency stability of ± 2. 5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. Interaction of the intra-cavity evanescent laser field with micro-particles in contact with the grating surface induces changes in the microwave beat signal, whose detection enabled real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 and \(20\,\upmu \mathrm{m}\), which represents the typical size of many fungal and bacterial pathogens. A limit of detection of \(\sim 500\,\mathrm{nm}\) was deduced.


Pump Power Slope Efficiency Absorb Pump Power Bragg Wavelength Beat Signal 
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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  1. 1.Integrated Optical Microsystems Group, MESA+ Institute for NanotechnologyUniversity of TwenteEnschedeThe Netherlands

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