TY - GEN
T1 - Comparative study of contact geometry for bottom-emitting 980 nm VCSELs
AU - Rosales, R.
AU - Schmeckebier, H.
AU - Boldt, C.
AU - Moser, P.
AU - Warren, M. E.
AU - Carson, R. F.
AU - Lott, J. A.
N1 - Publisher Copyright:
© 2017 SPIE.
PY - 2017
Y1 - 2017
N2 - Substrate-emitting GaAs based oxide-confined 980-nm vertical-cavity surface-emitting lasers (VCSELs) with top-surface high-frequency ground-source-ground contact pads are designed, fabricated, and characterized. The devices are composed of standard top and bottom epitaxially-grown AlGaAs distributed Bragg reflectors (DBRs). The top (p)DBR is capped with p-contact Ti then Au thin-film metals for uniform current injection and laser emission is through the GaAs substrate. The devices are realized on a single epitaxial wafer with n-ohmic-contacts placed on a thick (n+)GaAs buffer layer beneath the bottom (n)DBR and alternatively with the n-ohmic-contacts placed on an (n)GaAs intra-cavity layer lying within the same bottom (n)DBR. Static device parameters including threshold current and rollover current, differential resistance, peak optical output power, and wall-plug efficiency are extracted for VCSELs with oxide-aperture diameters ranging from about 3 to 9-μm and at different temperatures. At room temperature threshold currents are achieved from the sub-mA range up to about 3.5-mA with maximum output powers exceeding 15-mW. Increasing the temperature up to 85 °C slightly increases the threshold current while the peak output power is about halved. The differential resistance at the thermal rollover current is comparable for standard and intra-cavity n-metal-contacts. Small-signal analysis is performed for different bias currents, temperatures, oxide-aperture diameters, and the two n-contact options. Under optimal bias conditions the 3-dB bandwidth exceeds 15 GHz. Direct current modulation-based on-off keying signal generation is investigated from 10 to 40-Gb/s. The influence of an anti-reflection-coated substrate, a thinned substrate, and the combination of both is investigated and discussed.
AB - Substrate-emitting GaAs based oxide-confined 980-nm vertical-cavity surface-emitting lasers (VCSELs) with top-surface high-frequency ground-source-ground contact pads are designed, fabricated, and characterized. The devices are composed of standard top and bottom epitaxially-grown AlGaAs distributed Bragg reflectors (DBRs). The top (p)DBR is capped with p-contact Ti then Au thin-film metals for uniform current injection and laser emission is through the GaAs substrate. The devices are realized on a single epitaxial wafer with n-ohmic-contacts placed on a thick (n+)GaAs buffer layer beneath the bottom (n)DBR and alternatively with the n-ohmic-contacts placed on an (n)GaAs intra-cavity layer lying within the same bottom (n)DBR. Static device parameters including threshold current and rollover current, differential resistance, peak optical output power, and wall-plug efficiency are extracted for VCSELs with oxide-aperture diameters ranging from about 3 to 9-μm and at different temperatures. At room temperature threshold currents are achieved from the sub-mA range up to about 3.5-mA with maximum output powers exceeding 15-mW. Increasing the temperature up to 85 °C slightly increases the threshold current while the peak output power is about halved. The differential resistance at the thermal rollover current is comparable for standard and intra-cavity n-metal-contacts. Small-signal analysis is performed for different bias currents, temperatures, oxide-aperture diameters, and the two n-contact options. Under optimal bias conditions the 3-dB bandwidth exceeds 15 GHz. Direct current modulation-based on-off keying signal generation is investigated from 10 to 40-Gb/s. The influence of an anti-reflection-coated substrate, a thinned substrate, and the combination of both is investigated and discussed.
KW - Bottom-emitting vcsels
KW - Contact geometry
KW - Modulation bandwidth
KW - On-off keying modulation
KW - Semiconductor lasers
KW - Static characterization
KW - Vertical-cavity surface-emitting lasers (VCSELs)
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U2 - 10.1117/12.2253361
DO - 10.1117/12.2253361
M3 - Conference contribution
AN - SCOPUS:85017023571
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Vertical-Cavity Surface-Emitting Lasers XXI
A2 - Choquette, Kent D.
A2 - Lei, Chun
PB - SPIE
T2 - Vertical-Cavity Surface-Emitting Lasers XXI
Y2 - 1 February 2017 through 2 February 2017
ER -