Bandwidth enhancement and optical performances of multiple quantum well transistor lasers

Abstract

A detailed rate-equation-based model is developed to study carrier transport effects on optical and electrical characteristics of the Multiple Quantum Well Heterojunction Bipolar Transistor Laser in time-domain. Simulation results extracted using numerical techniques in small-signal regime predict significant enhancement in device optical bandwidth when multiple quantum wells are used. Cavity length and base width are also modified to optimize the optoelectronic performances of the device. An optical bandwidth of ≈60GHz is achieved in the case of 5 quantum wells each of 70Å widths and a cavity length of 200m.The observation of stimulated light emission (λ≈900nm) from the quantum well (QW) base region of the highspeed heterojunction bipolar transistor laser 1 (HBTL) has received significant attention in recent years. With a highly doped p-type base region, the transistor laser (TL) is expected to have a short radiative recombination lifetime that would make it faster than conventional optical sources for communication networks, i.e. diode lasers (DL).Thanks to its double functionality, i.e. electrical switching of the HBT and lasing operation, the TL has significant potential for ultrafast optoelectronic integrated circuits. As it is anticipated that the 3-terminal optoelectronic device will have a better optical bandwidth compared with a DL, optimization of QW-base structure is desirable. 2 Experimentally the optimization of the TL structure without taking into account the HBT response would be tedious, whereas only a few theoretical models have been developed for single quantum well (SQW) HBTL, for which simplified forms of conventional rate equations for DL have been implemented. 3,4,5 Recently a large signal analysis has been proposed 6 that simulates optical and electrical performances of a buried heterostucture TL with different number of QWs. However, this approach suffers from several drawbacks such as linear optical gain, which is only a good approximation for small signal analysis, and the neglect of tunneling effects between different QWs. In their work, the authors reported a recombination lifetime in the TL active region of

Effective mobility for sequential carrier transport in multiple quantum well structures

“…     (2) which corresponds to the average carrier velocity in the MQW. In a symmetric structure, the escape process is symmetric ( esc+ esc-…”

“…Due to the unique optical and electrical properties of low-dimensional materials, multiple quantum well (multiple QW, MQW) structures have found numerous applications in optoelectronics. The employment of MQWs is, however, usually accompanied by the poor perpendicular carrier transport, which limits the bandwidth in high-speed devices [1,2], the carrier injection efficiency in light-emitting devices [3,4], and the photocarrier collection efficiency in photovoltaic devices [5,6]. For decades, a great deal of theoretical and experimental studies have been carried out to gain our understanding on the carrier dynamics in such structures, including carrier scattering, capture, thermalization, and escape processes [7][8][9][10][11][12][13].…”

Voltage and Current Modulation at 20 Gb/s of a Transistor Laser at Room Temperature

“…Recently, low temperature operation of a vertical-cavity surface-emitting transistor laser (VCTL) has also been demonstrated [22]. Analytical modeling of the transistor laser has been discussed in [23] however, this falls short in agreeing with measured data of fabricated devices, specifically with regards to the low-bias resonance peak in the RF response. This is attributed to usage of inaccurate parameters in the model.…”

Spectral characteristics of a 1.3-µm npn-AlGaInAs/InP transistor laser under various operating conditions

“…Owing to its three-terminal structure, the TL can achieve output power control with different spectral characteristics compared with conventional lasers by applying a collector-base voltage. In addition, the TL has the potential to break the modulation speed limitations inherent in conventional LDs because shorter carrier recovery times can be achieved [5,6,7,8,9,10]. Until now, several studies on the 0.98-µm TLs have been have been conducted [11,12,13].…”