Integrated finely tunable microring laser on silicon

Journal name:
Nature Photonics
Volume:
10,
Pages:
719–722
Year published:
DOI:
doi:10.1038/nphoton.2016.163
Received
Accepted
Published online

Large-scale computer installations are severely limited by network-bandwidth constraints and energy costs that arise from architectural designs originally based on copper interconnects1. Wavelength-division multiplexed (WDM) photonic links can increase the network bandwidth but are sensitive to environmental perturbations and manufacturing imperfections that can affect the precise emission wavelength and output power of laser transmitters2, 3. Here, we demonstrate a new design of a three-terminal hybrid III–V-on-silicon laser that integrates a metal-oxide-semiconductor (MOS) capacitor into the laser cavity. The MOS capacitor makes it possible to introduce the plasma-dispersion effect4 and thus change the laser modal refractive index and free-carrier absorption (FCA) loss to tune the laser wavelength and output power, respectively. The approach enables a highly energy efficient method to tune the output power and wavelength of microring lasers, with future prospects for high-speed, chirp-free direct laser modulation. The concept is potentially applicable to other diode laser platforms.

At a glance

Figures

  1. The schematics of a hybrid MOS-type microring laser.
    Figure 1: The schematics of a hybrid MOS-type microring laser.

    a,b, 3D view (a) and cross-sectional view with a simulated fundamental TE mode and MOS capacitor region (dashed box) (b). c, Transmission electron microscopy image of a bonded InP-to-Si structure using an O2-plasma-assisted process20. BOX, buried oxide layer.

  2. Proof-of-concept device simulation.
    Figure 2: Proof-of-concept device simulation.

    a,b, Simulated 2D hole-distribution profiles with no bias in any of the terminals (a) and with forward biases of 2 V in P1 and 8 V in P2 (b). Inset: zoom-in hole-distribution profile around the MOS capacitor region. c, Simulated electron- and hole-concentration distribution in the respective n-InP and p-Si in a logarithmic scale as a function of MOS bias voltage. d, The resultant resonance shift and FCA in a 50 µm diameter device under a 0–6 V MOS bias voltage. Two pairs of InGaAsP/InP superlattices (SLs) are embedded in the n-InP layer.

  3. SEM images of the fabricated device.
    Figure 3: SEM images of the fabricated device.

    a,b, Top-view (a) and cross-sectional view (b) of a fabricated laser. Highlighted colour sections: red, microring laser (a) and active region (b); purple, Si; blue, III–V; green, BOX; yellow, selected metal contacts.

  4. Laser performance under different bias to MOS capacitor.
    Figure 4: Laser performance under different bias to MOS capacitor.

    a,b, LIV characteristics (a) and spectra of a 40 µm diameter device at different MOS bias voltages (b). c, Lasing wavelength versus leakage power between the terminals P2 and N in devices with 30, 40 and 50 µm diameters. Inset: leakage current density versus capacitor bias voltage.

  5. Thermal chirp correction demonstration in MOS-type microring lasers.
    Figure 5: Thermal chirp correction demonstration in MOS-type microring lasers.

    a, Device (40 µm) wavelength redshift from injection current heating (dashed lines) and locking (solid lines) by an appropriate MOS bias Vc. b, Lasing wavelength shift as a function of injection current increases and MOS bias voltages for 30, 40 and 50 µm diameter devices.

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Affiliations

  1. Hewlett Packard Labs, Hewlett Packard Enterprise, 1501 Page Mill Road, Palo Alto, California 94304, USA

    • D. Liang,
    • X. Huang,
    • G. Kurczveil,
    • M. Fiorentino &
    • R. G. Beausoleil

Contributions

D.L. conceived the idea, and led the simulation, fabrication and manuscript preparation. H.X. contributed to the modelling and fabrication and led the device characterization. G.K. contributed to the fabrication and testing platform set-up. M.F. and R.G.B. participated in the manuscript revision and high-level project supervision.

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The authors declare no competing financial interests.

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