17 research outputs found
High-Speed VCSELs with Strong Confinement of Optical Fields and Carriers
We present the design, fabrication, and performance of our latest generation high-speed oxide-confined 850-nm verticalcavity surface-emitting lasers. Excellent high-speed properties are obtained by strong confinement of optical fields and carriers. Highspeed modulation is facilitated by using the shortest possible cavity length of one half wavelength and placing oxide apertures close to the active region to efficiently confine charge carriers. The resulting strong current confinement boosts internal quantum efficiency, leading to low threshold currents, high wall-plug efficiency, and state-of-the-art high-speed properties at low bias currents. The temperature dependent static and dynamic performance is analyzed by current-power-voltage and small-signal modulation measurements
High Speed VCSELs and VCSEL Arrays for Single and Multicore Fiber Interconnects
Our recent work on high speed 850 nm VCSELs and VCSEL arrays is reviewed. With a modulation bandwidth approaching 30 GHz, our VCSELs have enabled transmitters and links operating at data rates in excess of 70 Gbps (at IBM) and transmission over onboard polymer waveguides at 40 Gbps ( at University of Cambridge). VCSELs with an integrated mode filter for single mode emission have enabled transmission at 25 Gbps over > 1 km of multimode fiber and a speed-distance product of 40 Gbps . km. Dense VCSEL arrays for multicore fiber interconnects have demonstrated 240 Gbps aggregate capacity with excellent uniformity and low crosstalk between the 40 Gbps channels
High-speed 850 nm VCSELs operating error free up to 57 Gbit/s
Error-free transmission is demonstrated at bit rates up to 57 Gbit/s back-to-back, up to 55 Gbit/s over 50 m fibre and up to 43 Gbit/s over 100 m fibre using an oxide-confined 850 nm high-speed vertical cavity surface-emitting laser with a photon lifetime optimised for high-speed data transmission
Design of an 845-nm GaAs vertical-cavity silicon-integrated laser with an intracavity grating for coupling to a SiN waveguide circuit
A short-wavelength hybrid GaAs vertical-cavity silicon-integrated laser (VCSIL) with in-plane waveguide coupling has been designed and optimized using numerical simulations. A shallow etched silicon nitride (SiN) grating is placed inside the cavity of the hybrid vertical-cavity silicon-integrated laser to both set the polarization state of the resonant optical field and to enable output coupling to a SiN waveguide with high efficiency. The numerical simulations predict that for apertures of 4 and 6-ÎŒm oxide-confined VCSILs operating at 845-nm wavelength, a slope efficiency for the light coupled to the waveguide of 0.18 and 0.22 mW/mA is achievable, respectively, while maintaining a low threshold gain of 583 and 589 cmâ1, respectively, for the lasing
Impact of Damping on Large Signal VCSEL Dynamics
The dependence of large signal VCSEL dynamics on damping is studied through time-domain measurements of turn-on transients and timing jitter for VCSELs having K-factors from 0.1 to 0.4 ns
Impact of Damping on High-Speed Large Signal VCSEL Dynamics
An investigation of the optimal relaxation oscillation damping for high-speed 850-nm vertical-cavity surface-emitting laser (VCSEL) under large signal operation is presented, using devices with K-factors ranging from 0.1 to 0.4 ns. Time-domain measurements of turn-on transients are used to quantify damping dependent rise times, overshoots, and signal amplitudes. Optical eye diagrams together with timing jitter and bit error rate measurements reveal a tradeoff between the rise time and the duration of the relaxation oscillations. To produce a high-quality eye at a specific data rate, a proper amount of damping is needed to simultaneously obtain sufficiently high bandwidth and low timing jitter. We found that for error-free transmission, a VCSEL with a 0.3 ns K-factor achieved the best receiver sensitivity at 10 and 25 Gb/s, whereas a less damped VCSEL with a 0.2 ns K-factor achieved the best sensitivity at 40 Gb/s
Silicon-Integrated Hybrid-Cavity 850-nm VCSELs by Adhesive Bonding: Impact of Bonding Interface Thickness on Laser Performance
The impact of bonding interface thickness on the performance of 850-nm silicon-integrated hybrid-cavity vertical-cavity surface-emitting lasers (HC-VCSELs) is investigated. The HC-VCSEL is constructed by attaching a IIIâV âhalf-VCSELâ to a dielectric distributed Bragg reflector on a Si substrate using ultrathin divinylsiloxane-bis-benzocyclobutene (DVS-BCB) adhesive bonding. The thickness of the bonding interface, defined by the DVS-BCB layer together with a thin SiO2 layer on the âhalf-VCSEL,â can be used to tailor the performance, for e.g., maximum output power or modulation speed at a certain temperature, or temperature-stable performance. Here, we demonstrate an optical output power of 2.3 and 0.9 mW, a modulation bandwidth of 10.0 and 6.4 GHz, and error-free data transmission up to 25 and 10 Gb/s at an ambient temperature of 25 and 85 °C, respectively. The thermal impedance is found to be unaffected by the bonding interface thickness
850 nm hybrid vertical cavity laser integration for on-chip silicon photonics light sources
The realization of 850 rim hybrid III-V/dielectric VCSELs is reported in order to realize low power consumption integrated light sources for SiN waveguide circuits, which find applications both in short-reach optical communication and optical sensors
20-Gb/s Modulation of Silicon-Integrated Short-Wavelength Hybrid-Cavity VCSELs
We investigate the dynamics of silicon-integrated 850-nm-wavelength hybrid-cavity vertical-cavity surface-emitting lasers (VCSELs). The VCSELs consist of a GaAs-based half-VCSEL attached to a dielectric distributed Bragg reflector on a silicon substrate using ultra-thin divinylsiloxane-bis-benzocyclobutene adhesive bonding. A 5-”m oxide aperture diameter VCSEL, with a small signal modulation bandwidth of 11 GHz, supports data transmission at bit rates up to 20 Gb/s. The modulation bandwidth and the large signal modulation characteristics are found to be impaired by the high thermal impedance