F. Delorme

10-wavelength 200-GHz channel spacing emitter integrating DBR lasers with a PHASAR on InP for WDM applications

A 10-wavelength 200-GHz channel spacing emitter was realized by monolithically integrating on InP a 10 distributed-Bragg-reflector laser array and a PHASAR used as a 10/spl rarr/1 combiner. The design of a wide-squared spectral bandwidth for the PHASAR as well as the lasers tunability ensure wavelength matching between the PHASAR transmission comb and the laser array comb. The channel spacing accuracy of the source is better than 25 GHz and the rejection is higher than 32 dB for all bias.

20-Gb/s integrated DBR laser-EA modulator by selective area growth for 1.55-μm WDM applications

For the first time, selective area growth (SAG) has been used for the monolithic integration of a distributed Bragg reflector (DBR) laser with an electroabsorption (EA) modulator, designed for WDM communication systems at 1.55 /spl mu/m. A 16-GHz bandwidth combined with a 6-nm tuning range make this component compatible with multiwavelength 20-Gb/s transmission experiments.

High reliability of high-power and widely tunable 1.55-/spl mu/m distributed Bragg reflector lasers for WDM applications

Single-mode operation with output power up to 100 mW is reported for the first time for InGaAsP-InP DBR lasers. These devices exhibiting a record 17-nm tuning range, have been realized using a three-step MOVPE process. The output power variations under tuning are limited to about 1.5 dB, and the tuning range remains quasiconstant with the output power. Using a two-wavelength DBR laser array with Bragg wavelengths spaced by 15 nm, 61 channels regularly spaced by 0.5 nm are accessible by controlling only two currents. Moreover systematic investigations of accelerated aging of these components have been realized for the first time. For all the tests performed on both active and tuning sections, no spectral degradations are observed, and the tunability remains unchanged. To define the lifetime of a tunable laser, e.g., a DBR laser, we propose a new failure criterion based on both active operating current and wavelength degradations. Using this criterion, the lifetime at 60/spl deg/C is estimated to be more than 7/spl middot/10/sup 4/ h, and is not limited by the wavelength degradation, but effectively by the operating current degradation.

A new distributed Bragg reflector laser for improved tuning

We propose a new distributed Bragg reflector laser using the phase variation of the Bragg facet reflectivity to improve the tunability. The modelling yields a 20 nm tuning range corresponding to a 8 nm increase of the classic DBR tunability. Preliminary experimental results confirmed this tuning improvement.<<ETX>>

Simple multiwavelength device fabrication technique using a single-grating holographic exposure

A simple technique, using a single-grating holographic exposure associated with localized selective etching steps, has been developed for multiwavelength device fabrication. Four-wavelength DBR laser arrays with a 5 nm Bragg wavelength spacing have been fabricated for wavelength division multiplexing (WDM) applications with this method. These devices exhibit uniformly low-threshold currents (10-15 mA), high-output powers (15 mW) and wide tunabilities (12 nm), leading to an overall accessible wavelength domain of 28 nm for the array.

Subnanosecond tunable distributed Bragg reflector lasers with an electrooptical Bragg section

For the first time, a DBR laser with an electrooptical Bragg section is reported for fast wavelength tuning operation. This structure is based on the photonic integration of a Fabry-Perot buried ridge stripe laser with a ridge waveguide modulator in which the grating is etched. By proper structure design and adjustment of the Franz-Keldysh quaternary gap used in the Bragg section, a 2.5-nm tuning range with six distinct modes is obtained for a -4 V voltage applied to the Bragg section. Under this tuning, the optical-output power variation is limited to 2.5 dB for a 370-/spl mu/m DBR length. Using this concept, we measured the best switching time between different wavelength channels ever reported on DBR lasers, on this device: 500 ps independently of the wavelength shift. >

Design, realization, and characterization of a ten-wavelength monolithic source for WDM applications integrating DBR lasers with a PHASAR

We present here the design, fabrication, and static as well as dynamic characteristics of a ten-wavelength, 200-GHz channel spacing emitter for wavelength-division multiplexing applications. The source is based on the monolithic integration on InP of a ten distributed Bragg reflector laser array with a square-shaped transmission response PHASAR. The specific design of the PHASAR is detailed. The continuous-wave operation-one channel at a time-demonstrates a high monomode stability with a rejection better than 32 dB for all channels and all injected currents; the 200-GHz channel spacing can be reached with an accuracy better than 25 GHz. High-speed characteristics demonstrate a 6.5-GHz direct modulation bandwidth at -3 dB for a 70-mA current in the 900-/spl mu/m-long active section. The chirp measured for a 2.5-Gb/s modulation with a 10-dB extinction ratio is less than 1.5 /spl Aring/ for every wavelength.

Subnanosecond tunable laser using a single electroabsorption tuning super structure grating

A new tunable laser structure using a single electroabsorption (EA) tuning super structure grating section for fast wavelength switching operation, has been realized. The tuning mechanism of this absorption change distributed Bragg reflector (DBR) laser is based on a localized absorption variation induced in a multielectrode EA-SSG section. These devices exhibit a 2.5-nm tuning range with three modes and a switching time, between two successive wavelength channels, shorter than 250 ps. The output power variation under tuning is lower than 1.2 dB.

A new tunable laser using a single electroabsorption tuning super structure grating for subnanosecond switching applications

A new tunable laser structure using a single electroabsorption (EA) tuning super structure grating (SSG) section for fast wavelength switching operation is reported. Instead of index change by carrier density or by thermal variation, the tuning mechanism of this absorption change (AC) distributed Bragg reflector (DBR) InGaAsP strained QW laser is based on a localized absorption variation induced in a Franz-Keldysh EA SSG section used as Bragg reflector. According to a simulation which takes into account the absorption and refractive index variations of the SSG section versus voltage and wavelength, an optimized device theoretically allows a wide tuning range of up to 11 nm with nine regularly spaced wavelength channels. Over this whole tuning range, the variation of the AC-DBR laser threshold gain is lower than 2 cm/sup -1/. Compared to a standard DBR laser exhibiting an 8-cm/sup -1/ threshold gain variation for the same wavelength shift, this AC-DBR laser would present extremely low threshold current and emitted power variations under tuning. Owing to its tuning mechanism, the switching time of the AC-DBR laser is independent of the wavelength shift, and only limited by the parasitic capacitance of the SSG ridge section. A test structure, easier to realize, with only a theoretical tuning range of 3 nm over four regularly spaced channels has been fabricated. These devices exhibiting a tuning range of 2.5 nm with three modes, present threshold current and output power variations under tuning of less than 8 mA and 1.2 dB, respectively. A switching time between two successive wavelength channels shorter than 250 ps has been observed, in agreement with typical capacitances of 0.8 pF/100 /spl mu/m measured on the SSG section.

Wavelength aging analysis of DBR lasers using tuning section IM frequency response measurements

Systematic IM frequency response measurements have been performed on the tuning section of distributed Bragg reflector lasers aged at 60/spl deg/C and 120/spl deg/C. The wavelength drift varies exponentially with aging time as well as carrier lifetime of the tuning section. The carrier lifetime increases with time indicating a wavelength drift mainly due to leakage current increase at high carrier density injection.Systematic IM frequency response measurements have been performed on tuning sections of DBR lasers aged at 60/spl deg/C and 120/spl deg/C. The wavelength drift varies exponentially versus aging time as well as the carrier lifetime of the timing section. The carrier lifetime increases versus time indicating a wavelength drift mainly due to leakage current increase.