A. Catrina Bryce

Mode-Locked Laser Array Monolithically Integrated With MMI Combiner, SOA, and EA Modulator

The monolithic integration of four 10-GHz 1.55- μm AlGaInAs/InP mode-locked surface-etched distributed Bragg reflector lasers with a 4 × 1 multimode-interference optical combiner, a curved semiconductor optical amplifier, and electroabsorption modulator using relatively simple technologies-surface-etched distributed Bragg reflector and quantum-well intermixing-has been demonstrated. Our techniques have the advantage of eliminating crystal regrowth and antireflection coating processes that are required in traditional methods. The four channels can operate separately or simultaneously. They also can be synchronized at the same pulse repetition frequency by the injection mode-locked technique.

10-GHz Mode-Locked Extended Cavity Laser Integrated With Surface-Etched DBR Fabricated by Quantum-Well Intermixing

The 10-GHz passively mode-locked AlGaInAs/InP 1.55- μm extended cavity lasers integrated with optimized surface-etched distributed Bragg mirrors have been fabricated. A quantum-well intermixing process was used to provide low-absorption loss gratings with accurate wavelength control. The lasers produce 2.99-ps sech2-pulses with a time-bandwidth product (TBP) of 0.51.

160 GHz harmonic mode-locked AlGaInAs 1.55 μm strained quantum-well compound-cavity laser

We characterized the reflectivity and the modal discrimination of intracavity reflectors (ICRs) with different numbers of slots and presented harmonic mode-locking operation of a monolithic semiconductor laser comprising a compound cavity formed by a single deeply etched slot ICR fabricated from 1.55 μm AlGaInAs strained quantum well material. Gaussian pulses were generated at a 161.8 GHz repetition rate with a pulse duration of 1.67 ps and a time-bandwidth product of 0.81.

160-GHz Passively Mode-Locked AlGaInAs 1.55-

The first demonstration of harmonic mode-locked operation from a monolithic semiconductor laser comprising a compound cavity formed by twin deeply etched intracavity reflectors based on 1.55-μm AlGaInAs strained quantum-well material is presented. Nearly transform-limited Gaussian pulses are generated at 160-GHz repetition rate with a 1.67-ps pulse duration.

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Impurity free vacancy disordering (IFVD) using dielectric caps to induce intermixing in the GaAs/AlGaAs system is described. Silica is used to promote intermixing whilst strontium fluoride is used as a mask against intermixing. Selective bandgap-widening of GaAs/AlGaAs double quantum well laser material has been used to fabricate monolithic extended cavity strip- loaded waveguide lasers. With a differential shift of 21 nm in the wavelength of the photoluminescence peak, overall losses in the extended cavities were less than 6 cm-1 and a red-shift of the lasing spectrum with increasing passive section length is reported. Electroabsorption optical modulators integrated with passive waveguides have been fabricated using an epitaxial structure identical to that of the laser. At a wavelength of 861.6 nm, devices with a 400 micrometers long modulator section showed ON/OFF ratios greater than 35 dB for a reverse bias voltage of 3 V. A variation of the IFVD technique uses partial area coverage by a strontium fluoride mask under a silica cap to determine the amount of quantum well intermixing. The bandgap can then be varied at will across a wafer. Bandgap tuned lasers were fabricated using this technique. Five distinguishable lasing wavelengths were observed from five selected intermixed regions on a single chip. These lasers showed no significant change in transparency current, internal quantum efficiency or internal propagation loss, which indicates that the material quality was not degraded after intermixing.

m Strained Quantum-Well Compound Cavity Laser

The 45-GHz passively mode-locked AlGaInAs-InP 1.55- m lasers integrated with surface-etched distributed Bragg mirrors have been fabricated. Quantum-well intermixing was used to provide low absorption loss gratings with accurate wavelength control. The lasers produce 3.6-ps Gaussian pulses with time-bandwidth product of 0.57.

GaAs/AlGaAs photonic integrated circuits fabricated using impurity-free vacancy disordering

Intermixing the wells and barriers of quantum well structures generally results in an increase in the bandgap and is accompanied by changes in the refractive index. A range of techniques, based on impurity diffusion, dielectric capping and laser annealing, have been developed to enhance the quantum well intermixing (QWI) rate in selected areas of a wafer -- such processes offer the prospect of a powerful and relatively simple fabrication route for integrating optoelectronic devices and for forming photonic integrated circuits (PICs). Recent progress in QWI techniques is reviewed, concentrating on processes that are compatible with PIC applications and illustrated with device demonstrators.

Monolithic 45-GHz Mode-Locked Surface-Etched DBR Laser Using Quantum-Well Intermixing Technology

High output power 40 GHz 1.55 μm passively mode-locked surface-etched distributed Bragg reflector (DBR) lasers with monolithically integrated semiconductor optical amplifiers are reported. These are based on an optimized AlGaInAs/InP epitaxial structure with a three quantum well active layer and an optical trap layer. The device produces near transform limited Gaussian pulses with a pulse duration of 3.3 ps. An average output power during mode-locked operation of 130 mW was achieved with a corresponding peak power of >1 W.

Quantum well intermixing for optoelectronic integration

We report 40 GHz passively mode-locked 1.55 μm AlGaInAs/InP lasers with integrated tapered semiconductor optical amplifiers producing nearly transform limited pulses with a pulse width of 4.3 ps and average output power of 200 mW.

High power (130 mW) 40 GHz 1.55 μm mode-locked distributed Bragg reflector lasers with integrated optical amplifiers

A novel 10-GHz passively mode-locked AlGaInAs/InP 1.55μm laser was demonstrated with a low divergence angle (14.7° × 27.3°), a timing jitter of 194 fs (4–80 MHz), and an RF linewidth of 2 kHz.