Short Optical Pulse Generation and Modulation by a Multi-Section MQW Modulator/DFB Laser Integrated Light Source

Koichi WAKITA  Kenji SATO  Isamu KOTAKA  Yasuhiro KONDO  Mitsuo YAMAMOTO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E78-C   No.1   pp.50-54
Publication Date: 1995/01/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Ultrafast Optoelectronics)
Category: 
Keyword: 
optical pulse generation,  optical pulse coding,  MQW modulator,  optical soliton,  10 Gb/s,  

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Summary: 
A new device consisting of an optical pulse generation section and pulse coding section monolithically integrated on a single-chip has been developed. The pulse generation section consists of a multiple quantum well (MQW) electroabsorption modulator integrated with an MQW DFB laser. The modulator operates at large-signal modulation and low voltage (from 2 to 3-V DC bias with a 3.2-V peak-to-peak RF signal). The second modulator is operated independently as a pulse encoder. An approximately transform-limited optical pulse train, whose full width at half maximum (FWHM) in the time domain is less than 17-ps and spectral FWHM is 28-GHz, is obtained with a repetition frequency of 10-GHz. Compressive strain is introduced in both InGaAsP quantum wells in order to obtain efficient device characteristics. These include a low threshold current (18-mA) for the laser, and low driving voltage (30-dB for 3-V swing) and high-speed operation (over 12-GHz for a 3-dB bandwidth) for the modulators. Demonstrations show that this new device generates short optical pulses encoded by a pseudo-random signal at a rate of 10 Gbit/s. This is the first time 10 Gbit/s modulation has been achieved with a multi-section electroabsorption modulator/DFB laser integrated light source. This monolithic device is expected to be applied to optical soliton transmitters.