Fiber Communication Applications Research Articles

Optical frequency standard for optical fiber communication based on the Rb 5s → 5d two-photon transition

We report an optical frequency standard based on the 5s --> 5d two-photon transition in Rb atoms. The frequency of a lambda = 778 nm diode laser was locked to the two-photon transition. Second-harmonic generation and an optical phase-locked loop were used to transfer the frequency stability to lambda = 1.556 mum for use in optical fiber communication applications.

GaAs HIGH SPEED DEVICES AND CIRCUITS

This paper presents the R&D of GaAs-based high speed devices and circuits at the Hebei Semiconductor Research Institute (HSRI) in China. It is concerned with low noise and medium power GaAs-MESFET MMIC and monolithic laser diode driver and preamplifier for 2.4 Gb/s fiber communication application, GaAs-based high speed digital circuits like single and dual modulus frequency divider, digital/analog convertor, shift register, HEMT and HBT integrated circuits.

MQW wavelength-tunable DBR lasers with monolithically integrated external cavity electroabsorption modulators with low-driving voltages fabricated by selective-area MOCVD

Summary form only given. Recently, lasers with monolithically integrated external modulators fabricated using selective-area epitaxy in the InGaAs-InGaAsP material system have received much attention for applications in long distance fiber communication. As of yet little work has been done on lasers with monolithically integrated modulators in the InGaAs-GaAs material system. Applications for lasers with monolithically integrated external-cavity modulators in the InGaAs-GaAs material system include wavelength-division multiplexing (WDM) local area networks and differential absorption LIDAR systems, for both of which low chirp is desired. We present a multiple quantum well (MQW) wavelength-tunable distributed Bragg reflector (DBR) laser with monolithically integrated external-cavity electroabsorption (EA) modulator.

Long Wavelength Laser Diode Reliability and Lattice Imperfections

Reliable long wavelength laser diodes emitting in the 1.30−1.55 μm regime with an expected operating life greater than 25 years for optical fiber communication applications are now fabricated using a combined heavy screening and accelerated aging process. For a given laser structure, the reliability of the devices depends intricately on both the crystalline perfection of the complex buried-heteroepitaxial semiconductor structures as well as the qualities of structures external to the semiconductor, such as electrical contact, dielectric coating, bonding, and packaging structures external to the semiconductor. The former (crystalline perfection) determines the intrinsic property of the laser, while the latter qualities (electrical contact, etc.) determine the contact resistance, parasitic capacitance, heating, and mechanical and thermal stresses to which a packaged laser device is subjected during operation. Since device heating and external stresses both degrade laser performance and accelerate permanent damage—through processes such as crystalline defect formation, current leakage path development, and doping profile redistribution—a reliable laser device, therefore, requires both a perfect semiconductor structure and also a high-quality external structure. Realistically, however, this may not be easily achievable, especially when a development program is limited in resource and time. Proper choice of the critical material issues in a development process becomes crucial to the success of the program.

Guided Wave Devices Based on III-V Heterojunctionand Quantum Well Structures

ABSTRACTGuided wave technology based on III–V compound semiconductor materials is important for optical signal processing, fiber communication and sensor applications. The provision of heterojunction and quantum well materials by LPE, MBE, and MOCVD have led to new concepts and techniques in tailoring the properties of discrete devices and optoelectronic integrated circuits. This paper discusses the electro-optical properties of heterojunction, quantum well, superlattice based on two novel effects, the Franz-Keldysh effect in bulk materials and the quantum confined Stark effect in semiconductor quantum wells. The electroabsorption and electrorefraction properties resulted from these effects are utilized in the realization of some waveguide modulators. Materials based on InGaAsP/InP heterojunctions, InGaAs/GaAs strained layer quantum wells and InGaAs/InP quantum wells will be emphasized.

Improved light-output linearity in stripe-geometry double-heterostructure (Al,Ga)As lasers

Nonlinearities in the optical-power-output–versus–current characteristics of (Al,Ga)As stripe-geometry double-heterostructure lasers are found to be associated with excessive spectral broadening, asymmetries in the outputs from the two mirrors, and spatial movements of the lasing mode within the width of the stripe. Manifestations of these nonlinearities are severely deleterious in a variety of optical fiber communication applications. It is shown that the impact of these defects may be significantly reduced, with little lasing-threshold-current penalty, by fabricating devices with narrower stripe widths.