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Octave-spanning 10-GHz Er-doped solid-state optical frequency comb

Niccolò S. Barberio, Francesco Canella, Andrea Pertoldi, Benjamin Rudin, Oguzhan Kara, Florian Emaury, Antonio Caruso, Dario Giannotti, Francesco Leone, Paolo Laporta, Gianluca Galzerano

TL;DR

The paper demonstrates a compact, fully stabilized 10-GHz Er-doped solid-state optical frequency comb built entirely from commercially available components. It achieves an octave-spanning spectrum from 1150 to 2350 nm, with high power-per-mode and low phase noise, by splitting the cavity output into CEO/SH-based f-2f and supercontinuum branches and locking both f_rep and f_CEO to a GPS-disciplined RF reference. Key metrics include an integrated phase noise of 10.2 mrad (1 Hz–1 MHz), timing jitter under 163 fs, an f_CEO SNR of about 50 dB in 300 kHz, and a sub-10 kHz optical linewidth at 1560 nm. The platform promises practical deployment for optical communications, precision timing, and astronomical spectrograph calibration, bridging laboratory performance with field-ready operation.

Abstract

Optical frequency combs provide a phase-coherent interface between optical and microwave domains, underpinning advances in precision metrology, spectroscopy, and time-frequency transfer. Most conventional comb architectures are limited to sub-gigahertz repetition rates, constraining integration and scalability. Here, we demonstrate a compact, 10-GHz Er-doped solid-state frequency comb operating near the 1550 nm telecommunications window. The system, assembled entirely from commercially available components, produces a coherent spectrum spanning from 1150 nm to 2350 nm with exceptionally low intensity and phase noise. Full frequency stabilization of both pulse repetition and carrier envelope offset frequencies is demonstrated with respect to an RF reference. Comprehensive characterization reveals performance exceeding that of previously reported solid-state combs in power-per-mode and noise suppression. These results establish a robust and accessible platform for multi-gigahertz-repetition-rate comb synthesis, bridging laboratory-grade performance with practical deployment in optical communication, precision timing, and astronomical instrumentation.

Octave-spanning 10-GHz Er-doped solid-state optical frequency comb

TL;DR

The paper demonstrates a compact, fully stabilized 10-GHz Er-doped solid-state optical frequency comb built entirely from commercially available components. It achieves an octave-spanning spectrum from 1150 to 2350 nm, with high power-per-mode and low phase noise, by splitting the cavity output into CEO/SH-based f-2f and supercontinuum branches and locking both f_rep and f_CEO to a GPS-disciplined RF reference. Key metrics include an integrated phase noise of 10.2 mrad (1 Hz–1 MHz), timing jitter under 163 fs, an f_CEO SNR of about 50 dB in 300 kHz, and a sub-10 kHz optical linewidth at 1560 nm. The platform promises practical deployment for optical communications, precision timing, and astronomical spectrograph calibration, bridging laboratory performance with field-ready operation.

Abstract

Optical frequency combs provide a phase-coherent interface between optical and microwave domains, underpinning advances in precision metrology, spectroscopy, and time-frequency transfer. Most conventional comb architectures are limited to sub-gigahertz repetition rates, constraining integration and scalability. Here, we demonstrate a compact, 10-GHz Er-doped solid-state frequency comb operating near the 1550 nm telecommunications window. The system, assembled entirely from commercially available components, produces a coherent spectrum spanning from 1150 nm to 2350 nm with exceptionally low intensity and phase noise. Full frequency stabilization of both pulse repetition and carrier envelope offset frequencies is demonstrated with respect to an RF reference. Comprehensive characterization reveals performance exceeding that of previously reported solid-state combs in power-per-mode and noise suppression. These results establish a robust and accessible platform for multi-gigahertz-repetition-rate comb synthesis, bridging laboratory-grade performance with practical deployment in optical communication, precision timing, and astronomical instrumentation.
Paper Structure (4 sections, 8 figures)

This paper contains 4 sections, 8 figures.

Table of Contents

  1. Introduction
  2. Experimental setup
  3. Results
  4. Conclusion

Figures (8)

  • Figure 1: Simplified experimental setup of the 10-GHz optical frequency comb. CW laser: single-frequency laser; PM-DCF: polarization-maintaining dispersion compensated fiber; PM-1550: single-mode polarization-maintaining fiber; EDFA: erbium-doped fiber amplifier; PD: photodetector; PZT: piezoelectric transducer; GPS: GPS-disciplined Rb frequency standard; RFSA: RF spectrum analyzer; SC: supercontinuum; SH: second harmonic.
  • Figure 2: Optical spectrum and zoom showing the mode separation of 80 pm, corresponding to 10 GHz in frequency. The red dashed curve is the hyperbolic secant best fit profile.
  • Figure 3: Autocorrelation traces and optical spectra measured at the outputs (a)-(c) of the $f-2f$ amplifier and (b)-(d) SC amplifier.
  • Figure 4: Phase noise of the 10-GHz pulse repetition rate both in free-running (blue trace) and locked (red trace) to the 1-GHz reference (dark green trace, rescaled to 10 GHz frequency).
  • Figure 5: Power spectral density of the relative intensity noise of the 10 GHz oscillator (red trace), compared with those at the optical amplifier outputs: $f-2f$ branch (blue trace) and SC branch (green trace).
  • ...and 3 more figures