Joel S. Paslaski

108 GHz passive mode locking of a multiple quantum well semiconductor laser with an intracavity absorber

A two‐section multiple quantum well laser is passively mode locked without an external cavity at ∼108 GHz. The pulse widths average 2.4 ps and have a time‐bandwidth product of 1.1. Self‐pulsations at frequencies up to 8 GHz are also observed.

Active Q switching in a GaAs/AlGaAs multiquantum well laser with an intracavity monolithic loss modulator

Active Q switching in a GaAs/AlGaAs multiquantum well laser with an intracavity electroabsorption monolithic loss modulator is demonstrated. In this device, an efficient loss modulation is achieved through the quantum confined Stark effect in a modulator section and the enhanced carrier induced band shrinkage effect in an optical amplifier section. It is found that a picosecond pulse as narrow as 18.6 ps full width at half‐maximum is generated and a high repetition rate of more than 3 GHz is obtained.

Passive mode locking of a two‐section multiple quantum well laser at harmonics of the cavity round‐trip frequency

A multiple quantum well GaAs/AlGaAs laser with two electrically isolated contacts is passively mode locked in an external cavity at the first through sixth harmonics of the pulse round‐trip frequency of 1.17 GHz to produce pulses shorter than 10 ps. The repetition rate is switched between harmonics by adjusting the gain section current, and large hysteresis between the different repetition rates is observed, with up to four different repetition rates for the same gain current. The results are compared with small and large signal passive mode‐locking theories by considering modifications to the saturated gain recovery between pulses when the laser operates at different harmonics.

High-power microwave photodiode for improving performance of rf fiber optic links

The rf performance of fiber optic links is often limited by the maximum optical power rating of the photodiode receiver, particularly in short distance, point to point applications where the received power can be rather high. Required attenuation of the optical power can significantly compromise performance parameters such as the gain, noise, and dynamic range of the link, as well as adding extra cost and complexity in installing and maintaining the link. This paper presents results from the development of a high speed InGaAs photodiode (16 GHz) which can operate at a dc photocurrent as high as 15 mA, or 20 mW of received optical power.

Observation of modulation speed enhancement, frequency modulation suppression, and phase noise reduction by detuned loading in a coupled-cavity semiconductor laser

Simultaneous direct modulation response enhancement, phase noise (linewidth) reduction, and frequency modulation suppression are produced in a coupled‐cavity semiconductor laser by the detuned loading mechanism.

Vibration resistance, short coherence length operation, and mode-locked pumping in passive phase conjugate mirrors

Because the ring and semilinear passive phase conjugate mirrors use dynamic transmission holograms, they are insensitive to vibration and may be pumped with light of short coherence length or with picosecond mode‐locked laser light. Experimental demonstrations of these modes of operation are described.

High‐frequency modulation of AlGaAs/GaAs lasers grown on Si substrate by molecular beam epitaxy

We report on the frequency response of quantum well lasers on Si substrates grown by molecular beam epitaxy. Ridge waveguide lasers of 10 μm×380 μm having threshold currents as low as 40 mA were used in this study. Measurements were performed up to a frequency of 4.5 GHz with a resultant modulation corner frequency of 2.5 GHz when the laser was operated about 20% above the threshold.

Reduction of relative intensity noise of the output field of semiconductor lasers due to propagation in dispersive optical fiber

The effect of dispersive, linear propagation (e.g., in single‐mode optical fiber) on the intensity noise from semiconductor lasers is investigated. Relations between the frequency and amplitude noise variations of semiconductor lasers are obtained from the laser rate equations and used to calculate the change in the relative intensity noise (RIN) spectrum that occurs during dispersive propagation. Propagation in fiber with positive dispersion (D≳0) over moderate distances (several km for standard single‐mode fiber at 1.55 μm) is found to reduce the RIN over a wide range of frequencies. Measurements with a 1.56 μm distributed feedback laser confirm the main theoretical results and demonstrate reductions in RIN of up to 11 dB with 4 km of standard fiber.

High performance planar lightwave circuit triplexer with passive optical assembly

High performance, compact planar lightwave circuit based triplexers have been built and tested. The triplexers utilize lasers, photodiodes and filters that have been adapted to enable passive optical assembly of the triplexer.

Timing jitter and pulse energy fluctuations in a passively mode‐locked two‐section quantum‐well laser coupled to an external cavity

Stability of pulse energy and timing in a passively mode‐locked two‐section quantum‐well laser is measured. Spectral analysis of the 546‐MHz pulse train reveals rms timing jitter of 5.5 ps above 50 Hz and rms pulse energy fluctuations of <0.52% above 200 Hz.