Resonant normal-incidence separate-absorption-charge-multiplication Ge/Si avalanche photodiodes.

In this work the impedance of separate-absorption-charge-multiplication Ge/Si avalanche photodiodes (APD) is characterized over a large range of bias voltage. An equivalent circuit with an inductive element is presented for modeling the Ge/Si APD. All the parameters for the elements included in the equivalent circuit are extracted by fitting the measured S(22) with the genetic algorithm optimization. Due to a resonance in the avalanche region, the frequency response of the APD has a peak enhancement when the bias voltage is relatively high, which is observed in the measurement and agrees with the theoretical calculation shown in this paper.

Frequency response and bandwidth enhancement in Ge/Si avalanche photodiodes with over 840 GHz gain-bandwidth-product.

In this work we report a separate-absorption-charge-multiplication Ge/Si avalanche photodiode with an enhanced gain-bandwidth-product of 845 GHz at a wavelength of 1310 nm. The corresponding gain value is 65 and the electrical bandwidth is 13 GHz at an optical input power of -30 dBm. The unconventional high gain-bandwidth-product is investigated using device physical simulation and optical pulse response measurement. The analysis of the electric field distribution, electron and hole concentration and drift velocities in the device shows that the enhanced gain-bandwidth-product at high bias voltages is due to a decrease of the transit time and avalanche build-up time limitation at high fields.

A racetrack mode-locked silicon evanescent laser.

By utilizing a racetrack resonator topography, an on-chip mode locked silicon evanescent laser (ML-SEL) is realized that is independent of facet polishing. This enables integration with other devices on silicon and precise control of the ML-SEL's repetition rate through lithographic definition of the cavity length. Both passive and hybrid mode-locking have been achieved with transform limited, 7 ps pulses emitted at a repetition rate of 30 GHz. Jitter and locking range are measured under hybrid mode locking with a minimum absolute jitter and maximum locking range of 364 fs, and 50 MHz, respectively.

Integrated AlGaInAs-silicon evanescent race track laser and photodetector.

Here we report a racetrack resonator laser integrated with two photo-detectors on the hybrid AlGaInAs-silicon evanescent device platform. Unlike previous demonstrations of hybrid AlGaInAs-silicon evanescent lasers, we demonstrate an on-chip racetrack resonator laser that does not rely on facet polishing and dicing in order to define the laser cavity. The laser runs continuous-wave (c.w.) at 1590 nm with a threshold of 175 mA, has a maximum total output power of 29 mW and a maximum operating temperature of 60 C. The output of this laser light is directly coupled into a pair of on chip hybrid AlGaInAs-silicon evanescent photodetectors used to measure the laser output.

A hybrid AlGaInAs-silicon evanescent preamplifier and photodetector.

We report the integration of a hybrid silicon evanescent waveguide photodetector with a hybrid silicon evanescent optical amplifier. The device operates at 1550 nm with a responsivity of 5.7 A/W and a receiver sensitivity of -17.5 dBm at 2.5 Gb/s. The transition between the passive silicon waveguide and the hybrid waveguide of the amplifier is tapered to increase coupling efficiency and to minimize reflections.

31 GHz Ge n-i-p waveguide photodetectors on Silicon-on-Insulator substrate.

We report on evanescently coupled Ge waveguide photodetectors that are grown on top of Si rib waveguides. A Ge waveguide detector with a width of 7.4mum and length of 50 mum demonstrated an optical bandwidth of 31.3 GHz at -2V for 1550nm. In addition, a responsivity of 0.89 A/W at 1550 nm and dark current of 169 nA were measured from this detector at -2V. A higher responsivity of 1.16 A/W was also measured from a longer Ge waveguide detector (4.4 x 100 mum2), with a corresponding bandwidth of 29.4 GHz at -2V. An open eye diagram at 40 Gb/s is also shown.

A hybrid AlGaInAs-silicon evanescent waveguide photodetector.

We report a waveguide photodetector utilizing a hybrid waveguide structure consisting of AlGaInAs quantum wells bonded to a silicon waveguide. The light in the hybrid waveguide is absorbed by the AlGaInAs quantum wells under reverse bias. The photodetector has a fiber coupled responsivity of 0.31 A/W with an internal quantum efficiency of 90 % over the 1.5 mum wavelength range. This photodetector structure can be integrated with silicon evanescent lasers for power monitors or integrated with silicon evanescent amplifiers for preamplified receivers.

1310nm silicon evanescent laser.

We report the first 1310 nm hybrid laser on a silicon substrate. This laser operates continuous wave (C.W.) up to 105 degrees C. The room temperature threshold current of this laser is 30 mA, and the maximum single sided fiber-coupled output power is 5.5 mW.

Experimental and theoretical thermal analysis of a Hybrid Silicon Evanescent Laser.

In this work we present both experimental and theoretical thermal analysis of an electrically pumped hybrid silicon evanescent laser. Measurements of an 850 mum long Fabry-Perot structure show an overall characteristic temperature of 51 oC, an above threshold characteristic temperature of 100 oC, and a thermal impedance of 41.8 oC/W. Finite element analysis of the laser structure predicts a thermal impedance of 43.5 oC/W, which is within 5% of the experimental results. Using the overall characteristic temperature, above threshold characteristic temperature, and the measured thermal impedance, the continuous wave output power vs. current from the laser is simulated and is in good agreement with experiment.

Electrically pumped hybrid AlGaInAs-silicon evanescent laser.

An electrically pumped light source on silicon is a key element needed for photonic integrated circuits on silicon. Here we report an electrically pumped AlGaInAs-silicon evanescent laser architecture where the laser cavity is defined solely by the silicon waveguide and needs no critical alignment to the III-V active material during fabrication via wafer bonding. This laser runs continuous-wave (c.w.) with a threshold of 65 mA, a maximum output power of 1.8 mW with a differential quantum efficiency of 12.7 % and a maximum operating temperature of 40 degrees C. This approach allows for 100's of lasers to be fabricated in one bonding step, making it suitable for high volume, low-cost, integration. By varying the silicon waveguide dimensions and the composition of the III-V layer, this architecture can be extended to fabricate other active devices on silicon such as optical amplifiers, modulators and photo-detectors.

Multichannel dispersion compensation using a silicon waveguide-based optical phase conjugator.

We experimentally demonstrate dispersion compensation using a silicon-based optical phase conjugator. We achieve simultaneous transmission of four dense wavelength division multiplexing (DWDM) channels spaced at 100 GHz and operating at 10 Gbits/s over 320 km of standard fiber. The measured power penalty at bit error rate of 10(-9) is less than 0.3 dB.