P.F. Sciortino

Mode-locked hybrid soliton pulse source with extremely wide operating frequency range

The authors report a mode-locked pulse source with extremely wide operating frequency range and very stable operation, through the use of a long, linearly chirped Bragg reflector as the output coupler integrated in a fiber external cavity. A 1.55 mu m strained MQW laser diode is used, with one facet high reflectivity (HR) coated for improved cavity Q, and the other antireflection (AR) coated to allow coupling to the external cavity and suppress Fabry-Perot modes. Near-transform-limited pulses are obtained over a frequency range of 700 MHz around a system operating frequency of 2.488 GHz, with pulsewidths of 50 ps, as required for a practical soliton transmission system.<<ETX>>

Frequency response subtraction for simple measurement of intrinsic laser dynamic properties

The authors describe a new technique for extracting the intrinsic laser-diode dynamic properties accurately. This simple technique eliminates the need for accurate microwave calibration of the test equipment and problems of microwave reflections, nonideal frequency response of laser mount, and detector. The effect of the parasitic components of the laser diode are also eliminated from the results so that measurements of important dynamic properties of the laser can be found up to high frequencies (10-20 GHz) on standard laser diodes. The techinque being used to measure variations of resonance peak and damping factor at different bias levels for a standard bulk active region 1.3 mu m laser diode is shown.<<ETX>>

DFB lasers integrated with Mach-Zehnder optical modulator fabricated by selective area growth MOVPE technique

The first monolithically integrated DFB laser/Mach-Zehnder interferometric modulator fabricated by the selective area low pressure MOVPE growth technique is reported. A near 3-dB power divider at the Y-branches of the interferometer has been reproducibly achieved by a photolithographically defined dielectric mask used in the selective area growth technology and confirmed by an infrared near field imaging technique. A modulation depth of over 12 dB was achieved both in the forward and reverse bias to the arms of the phase modulator.<<ETX>>

High-speed, low chirp, directly modulated 1.55-/spl mu/m DFB laser sources for 10 Gbit/s local distribution

Summary form only given. In this paper we describe 1.55-/spl mu/m DFB lasers for communications applications using p-doped compressively strained multiple quantum well (MQW) active regions to provide devices with extremely high modulation bandwidths and low wavelength chirp.

Tunable electroabsorption modulated laser integrated with a bent waveguide distributed-feedback laser

The fabrication of the first 1.55-/spl mu/m wavelength tunable electroabsorption modulated laser integrated with a bent waveguide distributed-feedback laser is reported. A low-threshold and stable single-mode operation is obtained when the devices were uniformly pumped. A single-mode output power close to 10 mW from a single-mode fiber (40 mW in free space) is obtained with a 0 V bias to the modulator and an extinction ratio of up to 15 dB at 2.5 V. This single mode stability is due to the continuously distributed phase shift implemented in the structure. With a nonuniform injection, it was possible to select one particular mode out of the three neighboring modes inside the broad-reflection band of the reflector. A tuning range of 3.5 mm was obtained while maintaining an output power of more than 2 dBm from each mode.

Ultrawide bandwidth 1.55-um lasers

This paper describes the essential elements for creating a practical wide bandwidth directly modulated laser source. This includes considerations of the intrinsic limitations of the laser structure, due to the resonant frequency and damping of the laser output, together with carrier transport issues to allow carriers in the device active region to be efficiently modulated at high speeds. the use of a P-doped compressively strained multiple-quantum well active region to provide high intrinsic speed and remove transport limitations is described, together with record setting results of 25 GHz modulation bandwidth for a 1.55 micrometer Fabry-Perot laser and 26 GHz bandwidth for a 1.55 micrometer DFB laser. The challenges of providing high bandwidth electrical connections to the laser on a suitable submount, together with fiber attachment and microwave packaging, are discussed. Results of fully packaged 1.55 micrometer DFB lasers with 25 Ghz modulation bandwidth are shown. Digital modulation of the packaged 1.55 micrometer DFB including impedance matching is described, and the transient wavelength chirp is presented. This low chirp is reduced further using an optical filter, to provide a 10 GBit/s source with chirp similar to that of an external electroabsorption modulator.

High-power mode-locked hybrid pulse source using two-section laser diodes

We describe a mode-locked hybrid pulse source with a two-section laser diode to obtain short mode-locked pulses (23 ps) with an average power of 7.8 mW, a high peak power of 137 mW, and a repetition rate of 2.51 GHz. The hybrid laser incorporates a two-section laser and an optical fiber cavity with an integrated Bragg reflector. The Bragg reflector controls the operating wavelength to subnanometer precision and also confines the bandwidth of the pulses so as to keep the time-bandwidth product below 1.

Enhanced modulation bandwidth of strained MQW lasers

The authors compare the dynamic properties of bulk, lattice-matched, and strained multiple-quantum-well (MQW) 1.3- mu m Fabry-Perot lasers up to high bias levels. They show that long-wavelength strained MQW lasers can have a higher intrinsic bandwidth than bulk active and lattice matched MQW lasers, and that a -3-dB bandwidth of over 30 GHz can be expected from devices with a thin separate confinement heterostructure if a low parasitic device structure is used. It is found that the K factor used to determine maximum bandwidth in bulk active laser diodes is unsuitable for strained MQW devices, where a linear relationship of damping/(resonance frequency) is not observed at high power levels.<<ETX>>

SBS suppression using a multichannel tunable laser with data encoding capability

Summary form only given. In this paper, we report a new laser transmitter device that utilizes a simple, low-amplitude voltage dither signal to realize a high stimulated Brillouin scattering (SBS) threshold with low residual amplitude modulation (AM). This method relies on an intracavity phase modulator to dither the lasing wavelength, thereby broadening the optical spectrum with high uniformity. We demonstrate an SBS threshold of 25.0 dBm by applying a 100 kHz, 95 mV/sub pp/ triangle wave to the on-chip phase modulator. The resultant residual AM is only 1.2%. In addition, this laser transmitter may be tuned between four wavelength-division multiplexing (WDM) channels and permits data encoding without an external amplitude modulator.

Short optical pulse generated by integrated MQW DBR laser/EA-modulator fabricated by selective-area MOVPE

Summary form only given. The authors report on the generation of short optical pulses by utilizing the nonlinear absorption characteristics of a multiple quantum well (MQW) electroabsorption (EA) modulator, which is monolithically integrated with an MQW wavelength-tunable distributed Bragg reflector (DBR) laser on a single chip. Preliminary measurements show that optical pulses as short as 39 ps have been generated at a repetition rate of 3 GHz with a broad tuning range of 5.4 nm near 1554-nm lasing wavelength. The bandgap energies of both the narrow-gap active MQW region and the wide-gap passive MQW region are controlled by the oxide width and grown at the same time using selective-area epitaxy by metal-organic vapor-phase epitaxy (MOVPE). >