Mark E. Overberg

Mutual Injection Locking of Monolithically Integrated Coupled-Cavity DBR Lasers

We present a photonic integrated circuit (PIC) composed of two strongly coupled distributed Bragg reflector (DBR) lasers. This PIC utilizes the dynamics of mutual injection locking to increase the relaxation resonance frequency from 3 GHz to beyond 30 GHz. Mutual injection-locking and external injection-locking operation are compared.

Optical AND and NOT gates at 40 Gbps using electro-absorption modulator/photodiode Pairs

We demonstrate an optical gate architecture using electro-absorption modulator/photodiode pairs to perform AND and NOT functions. Optical bandwidth for both gates reach 40 GHz. Also shown are AND gate waveforms at 40 Gbps.

Integrated Guided-Wave Photodiode Using Through-Absorber Quantum-Well-Intermixing

A high-speed, high-saturation power photodiode compatible with a relatively simple monolithic integration process is described. The detector is comprised of an intrinsic bulk absorption layer, an electron drift region, and a field termination layer, and is grown above a main waveguide core comprised of a number of quantum wells, which are used as the active region of a phase modulator. Through-absorber quantum-well-intermixing is used to blue-shift the bandedge of the underlying quantum wells, reducing the optical losses of that material. The detectors demonstrate quantum efficiency, input saturation power, and 3-dB bandwidth of 50 GHz.

Optical logic gates using interconnected photodiodes and electro-absorption modulators.

We demonstrate an optical gate architecture with optical isolation between input and output using interconnected PD-EAMs to perform AND and NOT functions. Waveforms for 10 Gbps AND and 40 Gbps NOT gates are shown.

High-speed switching of a 1.55-μm symmetric SEED

We demonstrate high-speed switching of a symmetric self-electrooptic effect device (S-SEED) operating at 1550 nm. Transitions faster than 10 ps are observed, verifying the suitability of this technology for integrated logic operations beyond 40 GHz.

InP tunable ring resonator filters

Optical channelizing filters with narrow linewidth are of interest for optical processing of microwave signals. Fabrication tolerances make it difficult to place exactly the optical resonance frequency within the microwave spectrum as is required for many applications. Therefore, efficient tuning of the filter resonance is essential. In this paper we present a tunable ring resonator filter with an integrated semiconductor optical amplifier (SOA) fabricated on an InP based photonic integrated circuit (PIC) platform. The ring resonance is tuned over 37 GHz with just 0.2 mA of current injection into a passive phase section. The use of current injection is often more efficient than thermal tuning using heaters making them useful for low-power applications. The single active ring resonator has an electrical FWHM of 1.5 GHz and shows greater than 16 dB of extinction between on and off resonance. The effects of SOA internal ring gain and induced passive loss on extinction and linewidth will be shown. Agreement between experimentally demonstrated devices and simulations are shown. The integration of the active and passive regions is done using quantum well intermixing and the resonators utilize buried heterostructure waveguides. The fabrication process of these filters is compatible with the monolithic integration of DBR lasers and high speed modulators enabling single chip highly functional PICs for the channelizing of RF signals.

All-optical XOR using 1550-nm high-speed S-SEEDs and integrated micro-optics

We demonstrate a compact, all-optical XOR gate at 1550 nm by integrating three symmetric self-electrooptic effect devices (S-SEEDs) with micro-optics. Each S-SEED operates as a NAND or NOR gate and can switch faster than 10 ps.

Enhanced frequency response in monolithically integrated coupled cavity lasers and electro-absorption modulator

We present the bandwidth enhancement of an EAM monolithically integrated with two mutually injection-locked lasers. An improvement in the modulation efficiency and bandwidth are shown with mutual injection locking.

Frequency response enhancement in integrated coupled-cavity DBR lasers

We present a photonic integrated circuit (PIC) composed of two strongly coupled lasers. This PIC utilizes the dynamics of mutual injection locking to increase the relaxation resonance frequency from 3 GHz to beyond 30 GHz.

A thin film TaN resistor reliability evaluation

A reliability evaluation for TaN thin film resistors based on accelerated life test experiments is presented. The resistors degrade by a gradual resistance increase and the functional dependence on time and temperature has been established. Normalized resistance increases with a ln(t) time dependence, with an activation energy of 1.55 eV. Current was shown not to be an independent acceleration factor, aside from its effect on Joule heating. Assuming a 1% failure criterion, a characteristic life of 9 × 106 h has been established for Tj = 125°C. The local encapsulation environment is believed to play a role in resistor degradation. The data are consistent with a model based on gradual conversion to non-conducting of a portion of the TaN film, suggested to be oxidation originating from residual water in the benzocyclobutene encapsulating film.