The influence of gain compression factor on dynamical properties of single level InAs/GaAs quantum dot lasers
📝 Abstract
In this paper, by representing a single level rate equation model for InAs/GaAs quantum dot lasers and computations by fourth order Runge-Kutta method some characteristics of the output laser are considered. The change of photon number in time and current and also the output power versus current with different gain compression factors are investigated for lasing from ground state (GS). Afterwards, the response function of small signal modulation for ground state in constant current but different gain compressions is surveyed. At last, we find an optimum value for gain compression factor in lasing from GS.
💡 Analysis
In this paper, by representing a single level rate equation model for InAs/GaAs quantum dot lasers and computations by fourth order Runge-Kutta method some characteristics of the output laser are considered. The change of photon number in time and current and also the output power versus current with different gain compression factors are investigated for lasing from ground state (GS). Afterwards, the response function of small signal modulation for ground state in constant current but different gain compressions is surveyed. At last, we find an optimum value for gain compression factor in lasing from GS.
📄 Content
The influence of g properties of singl Mostafa Qorbani, Esfan Departmen *Corresp Abstract In this paper, by representing a sin computations by fourth order Runge The change of photon number in tim gain compression factors are inves function of small signal modulation surveyed. At last, we find an optimu PACS numbers: 42.81.-i, 71.10.Li, 73.21.La Keywords: quantum dot lasers, gain
I.
Introduction
Semiconductor lasers have found a b
in telecommunication, CD ROM, L
signal processing, etc. Quantum dot (Q
been of interest due to their exclusive
such as law threshold current, low
sensitivity, and high optical gain, quan
and modulation speed are superior to
semiconductor lasers, owing to their d
of states1, 2.
Until now, many researchers have
effect of factors such as cavity len
temperature 3, QD size 4, indium per
substrate index6 on the laser. In this pa
investigate the effect of gain compres
laser outputs in a single level InAs/GaA
The rest of this article is schedule
firstly, our single level model is explai
1
gain compression factor on dyn
le level InAs/GaAs quantum do
ndiar Rajaei*, Omid Hajizadeh and Mahdi Ahma nt of Physics, University of Guilan, Rasht, Iran ponding author, Email: Raf404@guilan.ac.ir
ngle level rate equation model for InAs/GaAs quant
e-Kutta method some characteristics of the output la
me and current and also the output power versus cur
stigated for lasing from ground state (GS). Afterw
n for ground state in constant current but different ga
um value for gain compression factor in lasing from
a, 73.21.Fg
n compaction, modulation bandwidth, threshold curr
big application
Laser printers,
QD) lasers have
characteristics
w temperature
ntum efficiency
other types of
discrete density
e surveyed the
ngth, working
rcentage 5, and
aper, we aim to
ssion factor on
As laser7.
ed as follows:
ined in section
II. In section III the simu
represented. We conclude then in
II.
Our Model
To study the dynamics of our
we have obtained the rate equat
level model illustrated in Fig. (1)
Fig. 1: The model for relaxati
conduction band of InAs/GaAs
namical
ot lasers
di Borji
tum dot lasers and
aser are considered.
rrent with different
wards, the response
ain compressions is
GS.
rent
ulation results are
n section IV.
r quantum dot laser,
ions through energy
)8
ion and escape in quantum dot laser 2
Rate equations: Considering the transitions taken into account in our model, in which only a wetting layer and a ground state are given, three rate equations can be achieved as follows: wl gs wl r wl gs wl gs wl N N N e I dt dN (1) gs gs gs g g g gs wl gs r gs wl gs WL gs S S P K V N N N dt dN 1 )1 2 ( (2) r gs p gs gs gs gs g g g gs N S S S P K V dt dS 1 )1 2 ( (3) Equations (1) to (3) must be solved simultaneously to obtain dynamical behavior of the laser. These equations can give both carrier and photon numbers9, 10. In equations (1) to (3), gs wl N N , and gs S are respectively the carrier population in the wetting layer and ground state, and photon population at ground state. Also, denotes the time for a transition detailed in Table 1 and following equations. gs is the nonlinear gain coefficient for the ground state level obtained as follows: a mg gs V (4) where is the active region volume and mg is the gain compression factor defined as: 2 2 hom 0 2 0 2 2 2 a gs r p cv mg V E m n t P e (5) Here, is the optical confinement factor, hom is the homogeneous broadening, 2 cv P is the square of transition matrix element, and is the photon lifetime.
Output power:
Output power of the ground state is as follows:
ca
g
gs
gs
gs
out
L
n
R
S
cE
P
2
1
log
1
,
(6)
in which
ca
L is the cavity length and is the mirror
reflection coefficient.
g
P is the probability of occupation of GS:
D
gs
g
N
N
P
gs
D
(7)
Relaxation and escape time are interrelated by the
following expressions:
T
k
E
E
N
D
b
gs
wl
wl
b
gs
wl
gs
gs
wl
exp
and
g
0
P
1 wl gs wl gs (8) in which wl is the effective density of states of WL, obtained by: 2 T k m b e wl (9)
Table 1: Parameters used in the s PARAMETER
Light speed (C) Recombination in the QD ( rt ) Average refractive index ( rn ) 8 Group velocity ( g V ) Degeneracy in GS ( gs D ) WL energy ( wl E ) GS energy ( gs E ) Temperature Initial relaxation time from GS to WL ( wl es0 ) Cavity length ( ca L ) Mirror reflection () Mirror reflection () Optical confin
This content is AI-processed based on ArXiv data.