DocumentCode :
1436318
Title :
New frontiers in quantum cascade lasers and applications
Author :
Capasso, Federico ; Gmachl, Claire ; Paiella, Roberto ; Tredicucci, Alessandro ; Hutchinson, Albert L. ; Sivco, Deborah L. ; Baillargeon, James N. ; Cho, Alfred Y. ; Liu, H.C.
Author_Institution :
Lucent Technol. Bell Labs., Murray Hill, NJ, USA
Volume :
6
Issue :
6
fYear :
2000
Firstpage :
931
Lastpage :
947
Abstract :
Recent advances and new directions in quantum cascade (QC) lasers are discussed. Invented in 1994 following many years of research on band-structure engineered semiconductors and devices grown by molecular beam epitaxy, this fundamentally new laser has rapidly advanced to a leading position among midinfrared semiconductor lasers in terms of wavelength agility as well as power and temperature performance. Because of the cascaded structure, QC lasers have a slope efficiency proportional to the number of stages. Devices with 100 stages having a record peak power of 0.6 W at room temperature are reported. QC lasers in the AlInAs-GaInAs lattice matched to InP material system can now be designed to emit in the whole midinfrared range from 4 to 20 /spl mu/m by appropriately choosing the thickness of the quantum wells in the active region. Using strained AlInAs-GaInAs, wavelengths as short as 3.4 /spl mu/m have been produced. New results on QC lasers emitting at 19 /spl mu/m, the longest ever realized in a III-V semiconductor laser, are reported. These devices use innovative plasmon waveguides to greatly enhance the mode confinement factor, thereby reducing the thickness of the epitaxial material. By use of a distributed feedback (DFB) geometry, QC lasers show single-mode emission with a 30-dB side-mode suppression ratio. Broad continuous single-mode tuning by either temperature or current has been demonstrated in these DFB QC lasers at wavelengths in two atmospheric windows (3-5 and 8-13 /spl mu/m), with continuous-wave linewidths <1 MHz when free running and /spl sim/10 KHz with suitable locking to the side of a molecular transition. These devices have been used in a number of chemical sensing and spectroscopic applications, demonstrating the capability of detecting parts per billion in volume of several trace gases. Sophisticated band-structure engineering has allowed the design and demonstration of bidirectional lasers. These devices emit different wavelengths for oppo- ite bias polarities. The last section of the paper deals with the high-speed operation of QC lasers. Gain switching with pulse widths /spl sim/50 ps and active modelocking with a few picosecond-long pulses have been demonstrated. Finally, a new type of passive modelocking has been demonstrated in QC lasers, which relies on the giant and ultrafast optical Kerr effect of intersubband transitions.
Keywords :
III-V semiconductors; Q-switching; aluminium compounds; distributed feedback lasers; gallium compounds; indium compounds; laser beam applications; laser beams; laser feedback; laser mode locking; laser modes; laser transitions; laser tuning; optical Kerr effect; optical pulse generation; quantum well lasers; reviews; 0.6 W; 1 MHz; 10 kHz; 19 mum; 2 to 20 mum; 298 K; 3 to 5 mum; 3.4 mum; 50 ps; 8 to 13 mum; AlInAs-GaInAs; AlInAs-GaInAs-InP; III-V semiconductor laser; InP; active modelocking; active region; applications; atmospheric windows; band-structure engineered semiconductors; bidirectional lasers; broad continuous single-mode tuning; capability; cascaded structure; chemical sensing; continuous-wave linewidths; current tuning; design; distributed feedback geometry; epitaxial material; free running; gain switching; giant optical Kerr effect; high-speed operation; innovative plasmon waveguides; intersubband transitions; lattice matched material; locking; midinfrared range; midinfrared semiconductor lasers; mode confinement factor; molecular beam epitaxy; molecular transition; opposite bias polarities; passive modelocking; picosecond-long pulses; power performance; pulse widths; quantum cascade lasers; quantum wells; record peak power; room temperature; side-mode suppression ratio; single-mode emission; slope efficiency; sophisticated band-structure engineering; spectroscopic applications; strained AlInAs-GaInAs; temperature performance; temperature tuning; thickness; trace gases; ultrafast optical Kerr effect; wavelength agility; Distributed feedback devices; Laser feedback; Laser modes; Laser transitions; Laser tuning; Quantum cascade lasers; Quantum well lasers; Semiconductor lasers; Temperature; Waveguide lasers;
fLanguage :
English
Journal_Title :
Selected Topics in Quantum Electronics, IEEE Journal of
Publisher :
ieee
ISSN :
1077-260X
Type :
jour
DOI :
10.1109/2944.902142
Filename :
902142
Link To Document :
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