HFE4192-58X
4.25GBPS 850NM VCSEL
NOTES
1.
Reliability is a function of temperature, see
www.finisar.com/aoc.php for details.
For the purpose of these tests, I
F
is DC current.
Threshold current varies as (T
A
– T
O
)
2
. It may either
increase or decrease with temperature, depending upon
relationship of T
A
to T
O
. The magnitude of the change is
proportional to the threshold at T
O
.
Slope efficiency is defined as
∆P
O
/∆I
F
.
To compute the value of Slope Efficiency at a temperature
T, use the following equation:
η(T) ≈ η(25
oC)*[1+(∆η/∆T)*(T-25)]
6.
Rise and fall times specifications are the 20% - 80%. Most
of the devices will measure <80ps fall time.
To compute the value of Series Resistance at a
temperature T, use the following equation:
R
S
(T)
≈
R
S
(25oC)*[1+∆R
S
/∆T)*(T-25)]
8.
These specifications are for the TOSA component alone.
Reflections introduced by any subsequent higher level
assembly may affect these values.
Monitor current tracking is defined as follows:
9.
2.
3.
Deltrk
=
I
PD
(P
O
=
0.75mW) / 0.75mW
I
PD
(P
O
=
0.45mW) / 0.45mW
10. Relaxation Oscillation Frequency (ROF) is determined by
the relationship:
4.
5.
ROF
=
1
2π
⋅
r
−
1
tc
⋅
τ2
−
r
t2
7
Where r= IF/ITH, tc is the photon lifetime (2.5ps), and
τ
2
is the spontaneous emission lifetime (1ns). Both tc and
τ
2
are functions of temperature. When operating at high
temperature, the r (IF/ITH) value can be significantly
reduced and still maintain adequate speed performance.
This is recommended in order to preserve reliability.
TYPICAL PERFORMANCE CURVES
Emitted Power vs. Current:
Power varies approximately
linearly with current above threshold.
Threshold Current vs. Temperature:
Threshold current
varies parabolically with temperature; thus it can be nearly
constant for a limited temperature range.
Emitted Power
η
Threshold Current
Pmax
I
TH
I
MIN
[1.1×10 (T-T
MIN
) +1]
-4
2
Typical operating current / power
I
th
Current
T
MIN
, I
MIN
Temperature
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