P.A. Morton

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>>

Analysis of gain in determining T/sub 0/ in 1.3 /spl mu/m semiconductor lasers

Rapid decrease of differential gain has been determined to dominate the temperature dependence of threshold current in 1.3-/spl mu/m multiquantum well and bulk active lasers giving rise to low values of T/sub 0/. Extensive experimental characterization of each type of device is described. Results are presented for the dependence of gain on chemical potential and carrier density as a function of temperature. The data indicate the important role of the temperature-insensitive, carrier density dependent chemical potential in determining differential gain. Modeling of the temperature dependence of threshold carrier density in MQW and bulk active lasers based on a detailed band theory calculation is described. The calculated value of T/sub 0/ depends on the structure of the active layer, e.g., multiquantum well versus bulk. However, the calculated values are substantially higher than measured. >

64 Gb/s all-optical demultiplexing with the nonlinear optical-loop mirror

The first complete nonlinear optical-loop mirror demultiplexing experiments including error-rate measurements are reported. Broadband demultiplexing of 16-, 32-, and 64-Gb/s, 2/sup 15/-1 data was performed using only semiconductor lasers. The penalty for demultiplexing a 64-Gb/s time-division multiplexed data stream to the 4-Gb/s fundamental rate was 2.2 dB at an error rate of 10/sup -9/. The switching pulse energy was 1.1 pJ.<<ETX>>

Dispersion-penalty-free transmission over 130-km standard fiber using a 1.55-μm, 10-Gb/s integrated EA/DFB laser with low-extinction ratio and negative chirp

Transmission performance of a 10-Gb/s integrated electroabsorption modulator/DFB laser has been evaluated in terms of the eye margin degradation and the receiver sensitivity penalty caused by the chromatic dispersion in the standard (non-DSF) fiber. Combination of low extinction ratio (/spl epsi/=5 dB) and negative chirp (/spl Delta/v=-0.01 nm) operation allows 10-Gb/s transmission over 130-km standard fiber without any dispersion penalty in receiver sensitivity (for 10/sup -9/ BER) and with a 7% eye margin for 10/sup -15/ BER.

Packaged hybrid soliton pulse source results 70 terabit.km/sec soliton transmission

A packaged hybrid soliton pulse source is used in a soliton transmission experiment employing sliding-frequency guiding filters. The source shows excellent stability and very clean tuning characteristics. Control of the operating frequency and wavelength are described. Error free transmission at 10 GBit/s is achieved over a distance of 27000 km.<<ETX>>

Theoretical model of the hybrid soliton pulse source

A complete model of the hybrid soliton pulse source based on a time-domain solution of the coupled-mode equations is described. The model predicts the novel wavelength self-tuning mechanism and large stability range seen with this source. Results show the output waveform, optical spectrum, and instantaneous frequency, providing accurate source characteristics for use in transmission simulations.<<ETX>>

Impedance‐corrected carrier lifetime measurements in semiconductor lasers

Differential carrier lifetime as a function of subthreshold bias current in 1.3 m bulk active lasers is obtained by measurement of small‐signal modulation of amplified spontaneous emission together with careful characterization of frequency‐ and current‐dependent device impedance. The strong influence of rapidly varying device impedance upon these measurements is illustrated. In contrast to other studies, neither saturation of differential lifetime at low currents nor linear dependence of spontaneous emission on carrier density is observed. Recombination parameters, fit from current versus carrier density, along with consistent fits of spontaneous emission versus carrier density, are presented.

Analysis of T0 in 1.3 μm multi‐quantum‐well and bulk active lasers

Temperature dependence of threshold in 1.3 μm semiconductor lasers is analyzed in terms of contributions due to gain, internal efficiency, internal loss, and nonradiative recombination. Rapid decrease of differential gain and roughly proportional increase in transparency carrier density are determined to dominate temperature dependence of threshold current. Auger recombination is found to play a secondary role in reducing T0 by compounding the effects of rapidly increasing threshold carrier density.

High-speed InGaAsP/InP multiple-quantum-well laser

The authors describe practical high-speed InGaAsP/InP lasers based on compressively strained quantum wells. Buried heterostructure lasers with threshold currents of 10 mA and slope efficiencies of 0.23 mW/mA are used. A modulation bandwidth of 20 GHz is obtained at a low drive current of 90 mA. A K factor of 0.25 ns is obtained and the intrinsic bandwidth of these lasers is estimated at 35 GHz.<<ETX>>