Top-Hat HELLISH-VCSOA for optical amplification and wavelength conversion for 0.85 to 1.3μm operation
© Chaqmaqchee et al.; licensee Springer. 2012
Received: 9 July 2012
Accepted: 29 August 2012
Published: 25 September 2012
The Top-Hat hot electron light emission and lasing in semiconductor heterostructure (HELLISH)-vertical cavity semiconductor optical amplifier (VCSOA) is a modified version of a HELLISH-VCSOA device. It has a shorter p-channel and longer n-channel. The device studied in this work consists of a simple GaAs p-i-n junction, containing 11 Ga0.35In0.65 N0.02As0.08/GaAs multiple quantum wells in its intrinsic region; the active region is enclosed between six pairs of GaAs/AlAs top distributed Bragg reflector (DBR) mirrors and 20.5 pairs of AlAs/GaAs bottom DBR mirrors. The operation of the device is based on longitudinal current transport parallel to the layers of the GaAs p-n junction. The device is characterised through I-V-L and by spectral photoluminescence, electroluminescence and electro-photoluminescence measurements. An amplification of about 25 dB is observed at applied voltages of around V = 88 V.
KeywordsHELLISH VCSOA GaInNAs Luminescence Amplification
Vertical cavity semiconductor optical amplifiers (VCSOAs) are a topic of increasing interest[1–3] for applications in optical communications. In principle, a VCSOA is a modified vertical cavity surface emitting laser with a reduced top mirror reflectivity and is driven below the lasing threshold. VCSOAs are potentially low-cost alternatives to in-plane SOAs. Unlike the SOAs, they are inherently polarisation insensitive, have high fibre-coupling efficiency, low power consumption, low temperature sensitivity, low noise figure and offer the possibility of fabrication and on-chip testing in two-dimensional arrays[4, 5].
Long-wavelength GaInNAs/GaAs quantum well (QW)-based VCSOAs were originally proposed as replacements for GaInAsP/InP QW due to its reduced temperature sensitivity and performance degradation[7, 8]. In addition, their growth on GaAs and their integrability with GaAs/Al(Ga)As distributed Bragg reflectors (DBRs) allowed them to be considered as the active region in 1.3-μm vertical cavity devices.
Epitaxial structure of the THH-VCSOA
Layer thickness (Å)
1 × 1017
1 × 1017
1 × 1017
Semi-insulating GaAs substrate
In this work, we demonstrate for the first time the operation of the device at 1.3-μm wavelengths at T = 300 K with the GaInNAs/GaAs active region. Optical and electrical pumping (photoluminescence (PL), electroluminescence (EL)) were investigated. By combining the two measurements, an electro-photoluminescence (EPL) technique was also performed, from which the light amplification is obtained. The highest gain was achieved when a voltage of V = 88 V was applied.
Under normal process, contacts 1 and 2 on the left side are pulsed with ±V, while contacts 3 and 4 on the right side are grounded (12 ± V34G). By applying a positive voltage (+V), the current flows along the n-channel between contacts 1 and 4. The current flows through the p-channel between contacts 2 and 3. The potential near contact 2 in the p-channel is higher than that in the n-channel (Vp > Vn), while the situation near contact 3 is the opposite (Vn > Vp), as shown in Figure 2b. The device, therefore, behaves in two different ways, causing transverse voltage difference across the p-n junction. Firstly, the potential begins to extend from length l 2 to point X0 and is consequently forward-biased. Thus, this region of the device acts as a light emitter. However, the region from point X0 to length l 3 is reversed-biased. So, this region of the device acts as a light absorber. When a negative voltage (−V) is applied, the two regions change their functionality. Thus, the device emits light near contact 3 and absorbs light near contact 2. The THH structure has both a forward- and reverse-biased region in the same p-n junction plane, which can be flipped over by changing the polarity of the applied voltage.
Results and discussion
The THH-VCSOA device with 1-mm (p-channel) and 1.6-mm (n-channel) contact separation is investigated. The device is characterised using EL, PL and EPL techniques to obtain the amplification. The optical gain at λ ~ 1.27 μm is voltage dependent and reaches its maximum of 25 dB at an applied voltage of 88 V. The advantage of using such device is the application of longitudinal electric fields along the active layer, leading to the conclusion that THH-VCSOA works as an optical amplifier and absorber at around the λ = 1.3 μm window of communications.
Distributed Bragg reflector
Vertical cavity semiconductor optical amplifier
Top-Hat hot electron light emission and lasing in semiconductor heterostructure.
FAIC is grateful to the Ministry of Higher Education and Scientific Research of Iraq for their financial support. We are grateful to the Institute for Systems Based on Optoelectronics and Microtechnology in Madrid for their assistance with the device fabrication. The authors are also grateful to Professor Mark Hopkinson and Dr. Maxim Hughes for growing the structures. Finally, we would like to thank the COST Action MP0805 for the collaborative research.
- Kimura T, Bjorlin S, Piprek J, Bowers JE: High-temperature characteristics and tunability of long-wavelength vertical-cavity semiconductor optical amplifiers. IEEE Photo Tech Lett 2003, 15: 1501–1503.View Article
- Bouche N, Corbett B, Kuszelewicz R, Ray R: Vertical-cavity amplifying photonic switch at 1.5 μm. IEEE Photo Technol Lett 1996, 8: 1035.View Article
- Bjorlin ES, Riou B, Abraham P, Piprek J, Chiu YJ, Black KA, Keating A, Bowers JE: Long-wavelength vertical-cavity semiconductor optical amplifiers. IEEE J Quant Elect 2001, 37: 274. 10.1109/3.903078View Article
- Coldren CW, Larson MC, Spruytte SG, Harris JS: 1200 nm GaAs-based vertical cavity lasers employing GaInNAs multi quantum well active regions. Elect Lett 2000, 36: 951–952. 10.1049/el:20000365View Article
- Bjorlin ES, Bowers JE: Noise figure of vertical-cavity semiconductor optical amplifiers. IEEE J Quant Elect 2002, 38: 61. 10.1109/3.973320View Article
- Larson MC, Kondow M, Kitatani T, Tamura K, Okai M: Photo pumped lasing at 1.25 μm of GaInNAs-GaAs multiple-quantum-well vertical cavity surface emitting laser. IEEE Photo Tech Lett 1997, 9: 1549–1551.View Article
- Miyashita N, Shimizu Y, Okada Y: Carrier mobility characteristics in GaInNAs dilute nitride films grown by atomic hydrogen-assisted molecular beam epitaxy. J Appl Phys 2007, 102: 044904. 10.1063/1.2770833View Article
- Björlin ES, Rious B, Keating A, Abraham P, Chiu Y-J, Piprek J, Bowers JE: 1.3 μm vertical cavity amplifier. IEEE Photo Lett 2000, 12: 951–953.View Article
- Chaqmaqchee FAI, Mazzucato S, Oduncuoglu M, Balkan N, Sun Y, Gunes M, Hugues M, Hopkinson M: GaInNAs-based HELLISH-vertical cavity semiconductor optical amplifier for 1.3-μm operation. Nano Res Lett 2011, 6: 1–7.View Article
- Wah J-Y, Balkan N, Boland-thoms A, Roberts JS: Hot electron light emission and absorption processes in Top Hat structured bi-directional wavelength converter/amplifier. Physica E: Low Dimens Syst Nanostruct 2003, 1: 610–612.View Article
- Wah J-Y, Boland-Thoms A, Balkan N: The operation of a novel optically modulated vertical-cavity semiconductor optical amplifier with wavelength converting functionality. Phys Stat Sol (c) 2005, 2: 3100–3103. 10.1002/pssc.200460740View Article
- Wah J-Y, Balkan N: Low field operation of hot electron light emitting devices: quasi-flat-band model. IEE Proc Optoelectron. 2004, 151: 483.View Article
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