| 11. |
- Haglund, Åsa, 1976
(författare)
-
Mode and Polarization Control in VCSELs using Surface Structures
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The vertical-cavity surface-emitting laser (VCSEL) is a novel, low-cost light source with many attractive performance characteristics, such as low operating current, circular output beam, and high modulation bandwidth at low currents. This together with its easy integration into two-dimensional arrays has made it an established transmitter in short-distance single and parallel fiber-optical links, and new applications are continuously arising. One example is new network architectures where the advantages of free-space optical interconnects are utilized, which include interference-free cross connections in multi-dimensional topologies. Other examples are gas sensing, laser printing, optical storage, and longer distance fiberoptical communication. Many of these applications require a single frequency light source with an output power of several milliwatts, often with a stable polarization state. Unfortunately, the VCSEL has a tendency to lase at several wavelengths, referred to as multimode operation, due to its relatively large transverse dimensions. In addition, it has frequently an unpredictable polarization state due to symmetry in the device geometry, and isotropic material properties. The aim of this work was first to pin-point the performance differences between single and multimode VCSELs, with focus on the high-speed modulation characteristics, and secondly to develop a monolithic technique to achieve single mode and polarization stable operation in VCSELs. In the first part, high-speed single and multimode VCSELs were designed, fabricated and characterized. Both digital and analog modulation characteristics were analyzed from eye diagram, bit-error rate, and harmonic and intermodulation distortion measurements, and compared to numerical simulations. In the second part, a shallow surface structure was incorporated in the VCSEL to control the mode and polarization behavior. By using a disk-shaped surface relief a record-high single mode output power of 6.5 mW was achieved, and by further adding a surface grating to break the symmetry the polarization state was successfully pinned. No significant degradation of other important laser characteristics was observed due to the two surface structures.
|
|
| 12. |
|
|
| 13. |
- Kögel, Benjamin, 1979, et al.
(författare)
-
Short-wavelength tunable VCSELs
- 2009
-
Ingår i: European Semiconductor Laser Workshop (ESLW).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Larsson, Anders, 1957, et al.
(författare)
-
VCSELs for broadband access and interconnects
- 2009
-
Ingår i: Proc. 2009 International Nano-Optoelectronics Workshop, Stockholm-Berlin, August 2009. ; , s. 87-88
-
Konferensbidrag (refereegranskat)
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
- Ou, Yiyu, et al.
(författare)
-
Impedance characteristics and parasitic speed limitations of high speed 850 nm VCSELs
- 2009
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21, s. 1840-
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract—The impedance characteristics of high-speed oxideconfined 850-nm vertical-cavity surface-emitting lasers have been studied with the aim of identifying the importance of device parasitics for the modulation bandwidth. Through equivalent circuit modeling, it is confirmed that device parasitics have a major impact on the bandwidth and the importance of each individual circuit element has been investigated. According to the extrapolation of the parameters derived from S11 measurements below 20 GHz towards higher frequencies and assuming that the mesa capacitance can be reduced by adding a few extra oxide layers without significantly affecting series resistance, our model predicts that the 3-dB parasitic frequency can be increased from 22 to above 30 GHz. Accounting also for bandwidth limitations due to thermal effects, we expect an increase of the modulation bandwidth of several gigahertz which may enable direct current modulation at 40 Gb/s.
|
|
| 20. |
- Persson, K. A., et al.
(författare)
-
WCDMA radio-over-fibre transmission experiment using singlemode VCSEL and multimode fibre
- 2006
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 42:6, s. 372-374
-
Tidskriftsartikel (refereegranskat)abstract
- A high-performance singlemode VCSEL developed for analogue applications has been evaluated for use in a radio-over-fibre link for WCDMA in-building distributed antenna systems. The experiment showed penalty-free transmission over a wide range of input RF powers. The ACLR limited the downlink input RF power to less than -13dBm.
|
|
