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Dissertation
Actively mode-locked monolithic MQW laser diode integrated with an EA modulator
Doctor of Philosophy (Ph.D.), Drexel University
1999
DOI:
https://doi.org/10.17918/00008230
Abstract
Active mode locking of semiconductor laser diode is an attractive technique for transmission and signal processing applications because the optical pulse trains are synchronized with an external clock. Analytical investigations are reported for a monolithically integrated electroabsorption (EA) modulator with multiple quantum wells (MQW) laser diode at 1.55 [mu]m. The optical cavity length is 2170 [mu]m corresponding to a natural resonance frequency of ~19.3 GHz. The simulation results are compared with the measurements. The modeling is based on the single mode traveling wave laser diode rate equations. These partial differential equations relate forward and backward moving photon fields to electron density in space and time. The traveling wave rate equations are numerically solved by relating distance and time through group velocity and using the 4th order Runge-Kutta numerical technique. To get the frequency domain mode-locked pulses, a Fast Fourier Transform (FFT) with Taylor data windowing is applied to the time domain simulation results. The optical mode-locked pulses are examined as a function of the EA modulator reverse bias voltage and modulation power. The shortest fullwidth at half maximum power (FWHM) of 7.00 and 7.63 ps are obtained in the measurement and the simulation respectively for the case of gain section bias current of 100 mA, EA modulator reverse bias voltage of -4.5 V, and sinusoidal RF power of 18 dBm at 19.3 GHz. It is also found that the mode-locked pulsewidth is getting broader as the EA modulator reverse bias voltage and the sinusoidal RF power are decreased. This thesis also compares the experimental and analytical results of other mode-locked laser diode dynamic behaviors. The optical spectra is periodic set of pulses instead of Gaussian profile in both cases of measurement and simulation. Coherency measurement and simulation show that the pulse train coherency times are 199 and 210 ps respectively for Ib = 100mA, Vb = -4.5V, and Pm = 15dBm at 19.3 GHz. The power locking ranges of 55 and 75 MHz are obtained for two different cases of I b = 100m. A, Vb = -4.5V, Pm = 18dBm and I b = 140mA, Vb = -4.5V, Pm = 15dBm, respectively. A good agreement in frequency mixing is also observed between measurement and simulation.
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Details
- Title
- Actively mode-locked monolithic MQW laser diode integrated with an EA modulator
- Creators
- Joong Hee Lee
- Contributors
- Afshin S. Daryoush (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xvii, 148 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991021888959004721