Transmission-line laser modeling of carrier diffusion in VCSEL

Measurement of the minority carrier diffusion length (L) can be performed by measurement of the rate of decay of excess minority carriers with the distance (x) of an electron beam excitation source from a p-n junction or Schottky barrier junction perpendicular to the surface in an SEM. In an ideal case, the decay is exponential according to the equation, I = Ioexp(−x/L), where I is the current measured at x and Io is the maximum current measured at x=0. L can be obtained from the slope of the straight line when plotted on a semi-logarithmic scale. In reality, carriers recombine not only in the bulk but at the surface as well. The result is a non-exponential decay or a sublinear semi-logarithmic plot. The effective diffusion length (Leff) measured is shorter than the actual value. Some improvement in accuracy can be obtained by increasing the beam-energy, thereby increasing the penetration depth and reducing the percentage of carriers reaching the surface. For materials known to have a high surface recombination velocity s (cm/sec) such as GaAs and its alloys, increasing the beam energy is insufficient. Furthermore, one may find an upper limit on beam energy as the diameter of the signal generation volume approaches the device dimensions.

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New time-domain model for active mode locking, based on the transmission line laser model

IEE Proceedings J Optoelectronics ◽

10.1049/ip-j.1989.0042 ◽

1989 ◽

Vol 136 (5) ◽

pp. 264 ◽

Cited By ~ 19

Author(s):

A.J. Lowery

Keyword(s):

Transmission Line ◽

Time Domain ◽

Mode Locking ◽

Domain Model ◽

Active Mode ◽

Laser Model ◽

New Time

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Design method for antenna arrays employing ferrite printed transmission line phase shifters

IEE Proceedings - Microwaves Antennas and Propagation ◽

10.1049/ip-map:20020146 ◽

2002 ◽

Vol 149 (1) ◽

pp. 33-40 ◽

Cited By ~ 5

Author(s):

A.D. Brown ◽

L.C. Kempel ◽

J.L. Volakis

Keyword(s):

Transmission Line ◽

Antenna Arrays ◽

Design Method ◽

Phase Shifters

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Composite right/left-handed transmission line with array of thermocouples for generating terahertz radiation

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200208 ◽

2020 ◽

Vol 92 (2) ◽

pp. 20502

Author(s):

Behrokh Beiranvand ◽

Alexander S. Sobolev ◽

Anton V. Kudryashov

Keyword(s):

Transmission Line ◽

Terahertz Radiation ◽

Transmission Lines ◽

Software Package ◽

Optical Pulses ◽

Capacitively Coupled ◽

Voltage Difference ◽

Left Handed ◽

Microwave Transmission ◽

Commercial Software Package

We present a new concept of the thermoelectric structure that generates microwave and terahertz signals when illuminated by femtosecond optical pulses. The structure consists of a series array of capacitively coupled thermocouples. The array acts as a hybrid type microwave transmission line with anomalous dispersion and phase velocity higher than the velocity of light. This allows for adding up the responces from all the thermocouples in phase. The array is easily integrable with microstrip transmission lines. Dispersion curves obtained from both the lumped network scheme and numerical simulations are presented. The connection of the thermocouples is a composite right/left-handed transmission line, which can receive terahertz radiation from the transmission line ports. The radiation of the photon to the surface of the thermocouple structure causes a voltage difference with the bandwidth of terahertz. We examined a lossy composite right/left-handed transmission line to extract the circuit elements. The calculated properties of the design are extracted by employing commercial software package CST STUDIO SUITE.

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