Olaf Hildebrand

Integrated interferometric injection laser: novel fast and broad-band tunable monolithic light source

A wide-range electronically wavelength-tunable InGaAsP-InP laser has been developed. This monolithic single-mode light source is based on interferometric principles. The authors report on successful fabrication and first experimental device characteristics obtained with these novel Y-coupled-cavity integrated interferometric injection lasers. For both the 1300 and 1500 nm wavelength regions, very large tuning ranges for 22 and 23 nm. respectively, were achieved by proper current adjustment. The minimum achieved linewidth of the nonoptimized devices is 35 MHz. Within the complete tuning range, the selection of 12 individual single-mode channels spaced by 2 nm is demonstrated with high-modulation bandwidths up to 5 GHz. A preliminary test of the wavelength switching behavior between two individual single modes indicates promising high-speed switching capabilities in the gigahertz range. >

The Y-laser: a multifunctional device for optical communication systems and switching networks

This paper gives a comprehensive review of the recent progress obtained with various operation modes of a Y-shaped all active waveguide device with three optical input/output ports, the so called Y-laser. Used as a monolithic semiconductor light source, single-mode emission with an extremely large cw tuning range of more than 50 nm is accessed. Single current step tuning spans up to 8-nm range. Several-GHz bandwidth AM and FM response is achieved. Operation as a wavelength processing device is demonstrated with data-stream transformation from short wavelength fiber windows (around 780 nm or 1310 nm) to the long wavelength window (1550 nm), as well as with ultra wide range wavelength conversion within the 1550-nm region, across +/-20 nm (blue and red shift). Optical high-speed space switching/gating functions are verified up to 1 Gb/s, and packet switching of 5-Gb/s data streams is demonstrated. Further features as a pulse reshaping device, as an electrically triggerable wavelength bistable device and as a mode locked pulse generator are addressed. Possible applications of this multifunctional device in future optical communication systems and switching networks are discussed. >

Multifunctional photonic switching operation of 1500 nm Y-coupled cavity laser (YCCL) with 28 nm tuning capability

The authors present new results on extended electrical tuning, fast spatial switching, and optically controlled wavelength conversion characteristics for the recently developed InP-based Y-laser structure. The devices have a 80 nm thick bulk InGaAsP active layer and are completely grown by metalorganic vapor phase epitaxy. The facets at both ends of the chip are as-cleaved without antireflective coating. The addressable range for electrically controlled wavelength switching was extended to the record value of 28 nm. When operated as a lossless 1:2 optical space switch, fiber-to-fiber gain >0 dB, extinction ratio >50 dB and high speed operation up to 1 Gb/s were shown. Optically triggered tunable wavelength conversion including dynamic operation was also demonstrated.<<ETX>>

6 THz range tunable 2.5 Gb/s frequency conversion by a multiquantum well Y laser

Improved monolithic interferometric semiconductor lasers in Y configuration are reported. When they are operated as electrically tunable light sources, single-longitudinal-mode emission with a very large CW tuning range up to 51 nm is obtained. By using all-quaternary compressively strained multi-quantum-well (MQW) active layers, low DC threshold currents down to >

Analysis and simple tuning scheme of asymmetric Y-lasers

We present an analysis of interferometric lasers in Mach-Zehnder configuration with emphasis on the recently realized asymmetric Y-laser, leading to simple design and tuning rules. By tailoring the Mach-Zehnder (MZ) filter function we obtain a large variety of designable channel spacings together with improved sidemode suppression and easy access for wavelength division multiplexing (WDM) functions and wavelength conversion. >

Modelocking of interferometric Y-lasers in an external cavity

The first report on active modelocking of interferometric Y-lasers in an external cavity are reported. Pulse widths between 20 and 30 ps for 1.3- mu m and 1.55- mu m devices were achieved by modulation of the injection current synchronously to the external cavity roundtrip frequency. A time-bandwidth-product of 0.97 was determined for 1.55- mu m devices.<<ETX>>

High speed and coherent transmission components

This paper focusses on research and development activities for discrete components used either in high speed direct modulation or coherent systems, respectively. By taking full benefit of highly advanced epitaxial growth techniques like LPMOVPE and GSMBE new device structures have been realized. On the transmitter side a SIBH laser structure is reported which is especially designed for extremely low parasitics allowing for a transmission speed in excess of 10 Gbit/s. Results on DFB-MQW lasers are presented. By making use of two dimensional effects these lasers have shown low threshold currents, high output power as well as narrow linewidth, which is of strong interest for both high bit rate and coherent transmission, Wavelength tunable lasers, such as multisection DFB or DBR lasers as well as a YCC-I3 laser, are investigated. With 3 section DFB-lasers a linewidth of 3.5 MHz has been obtained. A 4-channel FSK transmission experiment at 565 Mbit./s has been successfully performed. The passiv DBR lasers have shown a tuning range of 4.2 nm. With the novel YCC-I3 laser structure an enormous total tuning range of 22 nm together with a continuous tuning range of 1.15 nm with 20 dB sidemode suppression and a linewidth of 35 MHz has been achieved. Semiconductor travelling wave amplifiers are reported with high average internal gain of 28 dB at bias current of 50 mA. Using 4 cascaded amplifiers a 591 Mbit/s direct detection experiment of 279 km has been performed. Results on pin-photodiodes and APDs are presented. Optimized pin-detectors have been used to detect 20 Gbit/s pattern in a system experiment. Specially designed APDs are reported with a gain-bandwidth product of 70 GHz.