New theory on measuring gain and index changes in femtosecond pump probe studies suggests a spectral artifact is present which may have obscured the ultrafast response in previous studies of InGaAsP laser diode amplifiers. A femtosecond heterodyne pump-probe technique is implemented using an Erbium-doped stretched-pulse modelocked fiber laser centered at 1.55 gm and used to obtain simultaneous ...

It is well known that the gain–bandwidth product of an avalanche photodiode can be increased by utilizing a thin multiplication region. Previously, measurements of the excess noise factor of InP–InGaAsP–InGaAs avalanche photodiodes with separate absorption and multiplication regions indicated that this approach could also be employed to reduce the multiplication noise. This paper presents a sys...

We have theoretically estimated the change in refractive index A n produced by injection of free carriers in InP, GaAs, and InGaAsP. Bandfilling (Burstein-Moss effect), band-gap shrinkage, and free-carrier absorption (plasma effect) were included. Carrier concentrations of 1016/cm3 to 10i9/cm3 and photon energies of 0.8 to 2.0 eV were considered. Predictions of A n are in reasonably good agreem...

Spatial mode filters based on multimode interference couplers (MMI's) that offer the possibility of splitting off antisymmetric from symmetric modes are presented, and realizations of these filters in InGaAsP/InP are demonstrated. Measured suppression of the antisymmetric first-order modes at the output for the symmetric mode is better than 18 dB. Such MMI's are useful for monolithically integr...

A single waveguide laser with two separately addressed sections is fabricated using selective area intermixing of InGaAsP multiple quantum well grown on InP substrate. The selective intermixing of quantum wells is achieved by capping the two sections with PECVD grown silicon nitride and silicon dioxide respectively followed by rapid thermal annealing the device at 750°C for 30s prior to the fab...

A new structure of 1.55-μm pillar cavity is proposed. Consisting of InP-air-aperture and InGaAsP layers, this cavity can be fabricated by using a monolithic process, which was difficult for previous 1.55-μm pillar cavities. Owing to the air apertures and tapered distributed Bragg reflectors, such a pillar cavity with nanometer-scaled diameters can give a quality factor of 104-105 at 1.55 μm. Ca...

We demonstrated high-efficiency all-optical switching in an InGaAsP–InP photonic crystal resonator evanescently coupled with a microfiber. The nonlinearity was based on carrier injection by single-photon absorption of 980-nm pump light. Carrier-induced and thermally induced shifts of resonance wavelengths were observed under continuous-wave pumping. In pulse operation, an instantaneous refracti...

A new microlaser design based on the high-reflectivity whispering-gallery modes around the edge of a thin semiconductor microdisk is described and initial experimental results are presented. Optical confinement within the thin disk plane results in a microresonator with potential for single-mode, ultralow threshold lasers. Initial experiments use selective etching techniques in the InP/InGaAsP ...