Alpes Lasers . TC-3 Datasheet download pdf (Page 55)

Chapter 3: Starter kit (pulser, temperature controller etc) 7

3 Starter kit (pulser, temperature controller etc)

This chapter disc usse s properties of the Starter kit, used for pulsed mode lasers.

3.1 Operation of TE cooler

3.1.1 What is the dissipated heat of a pul sed QC laser?

Pulsed QC lasers in general work at threshold voltages of 9V. . . 12V and threshold currents

of 1A. . .3A, with maximum values of up to 13V and 10A. The peak power during operation

therefore can vary in the range of about 10W. . .130W. Depending on duty cycle, the mean

dissipated power normally is in the range of some Watts.

3.1.2 What temperatures can be reached with the TC-51?

Normally, the TC-51 is shipped with current limitation of 4.5A and alarm value of 65degC.

Depending on the heat sink used, temperatures between -35 and +60degC may be reached. Very

high and low temperatures induce more stress on the Peltier elements and therefore accelerate

ageing.

3.2 Important points concerning LDD pulser s

3.2.1 What are the possible pulse lengths and duty cycles?

The pulse driver LDD100 can amplify pulses with lengths of 5ns. . . 300ns and minimal period

of 100ns. Maximal duty cycle is 50% (with reduced stability and not continuously to prevent

overheating, up to 90%). The pulse generator TPG128 is capable of generating pulses with

lengths of 20ns. . . 200ns (with reduced stability down to 10ns) and period of 0.2us. . .10.5us.

Duty cycle can vary in the range of 0.1%. . .80% (with reduced stability up to 95%).

In combination with LDD100, only 50% duty cycle can be reached, since the power supply

in TPG128 which is feeding LDD100 is not speciﬁed for higher values. Provide external power

source for LDD100 if more than 50% is needed. In any case, contact Alpes Lasers SA ﬁrst, if

duty cycles of more than 5% are needed.

3.2.2 What is the "external power supply" used for?

The "exte rnal power supply" is a DC power supply provided by the user; it is connected (via

banana plugs) to the pulse driver LDD100 and is delivering the electrical power feeding the

laser. Any standard laboratory power supply can be used, as long as it is ripple-free (<=1%),

voltage regulated, with variable voltage from 0V to at least 35V, and capable of delivering 1A

DC for duty cycles up to 5%. For higher duty cycles, contact Alpes Lasers SA, since not all

lasers are capable of working at more than 5%.

3.3 Low-frequency bias current for modulation

This section describes use of a bias-T circuit for electrically controlled modulation of peak

emission wavelength.

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Alpes Lasers . TC-3 Datasheet Page 55