Dieter Baums

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. >

Polarization-independent and ultra-high bandwidth electroabsorption modulator in multiquantum-well deep-ridge waveguide technology

Electroabsorption modulators with polarization-independence of transmission (TE/TM sensitivity <0.4 dB at 1550 nm) over a wide wavelength range from 1540-1560 nm have been realized using tensile-strained InGaAs and InGaAsP quantum wells. Both designs show 42-GHz modulation bandwidth with a high bandwidth-to-drive-voltage ratio of >23 GHz/V. Polarization insensitivity of modulator transmission and chirp is demonstrated. Technical realization has been done in ridge waveguide technology with low-pressure MOVPE, reactive ion etching (RIE) for semiconductor etching and polyimide for planarization.

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 >

10 Gbit/s monolithic MQW-based wavelength converter in Michelson interferometer configuration

Summary form only given. In conclusion, we have reported on the first successful 10 Gbit/s operation of a compact MQW interferometric wavelength converter. The bandwidth was increased compared to previously reported MQW-based structures taking advantage of higher differential gain and optical confinement factor as achieved by optimizing the MQW layer structure.

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. >

Mode-locked laser realized by selective area growth for short pulse generation and optical clock recovery in TDM systems

We report on monolithically integrated active/passive coupled cavity mode locked lasers for 1.55 micrometer realized by selective area growth technology of InGaAs(P) quantum wells. Mode locked FP or DBR lasers are fabricated with an integrated cavity comprising up to three different band gaps. The devices emit short light pulses at around 10 GHz repetition rate with pulse width down to 8.7 ps. A time-bandwidth product of 0.5 is achieved for mode locked DBR lasers. Active/passive integrated mode locked laser is used for generation of optical 10 GHz clock signal from optical 10 Gb/s PRBS RZ data stream injected into the laser cavity.

Observation of wavelength bistability in the interferometric Y-laser

We report on wavelength-bistability in the symmetrical interferometric Y-laser. Two single mode spectra separated by 5.5 nm are observed at identical bias and changed through ramping of only one of the four currents by 17 mA. It is thus controlled as simple as wavelength tuning of our new asymmetrical Y-laser.

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>>

Progress in Y laser technology: Towards application specific designs

The interferometric Y laser has been shown to be a multifunctional device with frequency, space and time processing capabilities, suitable for numerous photonic switching and optical communication applications. Its characteristic feature is the broadband wavelength tunability across the whole spectrum of the semiconductor gain profile. The authors report on recent advances in Y laser technology leading to strong improvements of device properties, and first modifications and optimizations of the original structures making the components ready for system implementation. Various device geometry optimizations are under progress for different system requirements and applications. These structural and technological modifications together with some first experimentally obtained device characteristics are described.<<ETX>>