U.S. Philips Corporation

Hindrik Tjassens

Johannes T Kluitmans

Hendrikus G Kock

A laser diode module includes a rectangular box-shaped metal casing having a bottom (B), an even number of guide pins (1-14) being led through the bottom (B) in a standardized DIL order. In addition to the laser diode itself (LD) the laser diode module further includes a metal base carrier (BC) on which the laser diode (LD), a photo diode (PD) and a support (S) for the glass fiber (F) are installed. The laser diode module further includes a guide pin (9) which is inserted in the bottom (B) by means of a feedthrough insulator for electrically connecting the laser diode module to an external transmission line (MT). In order to achieve a proper matching of the laser diode module and the characteristic impedance of the external transmission line (MT), so that reflection phenomena are avoided and the laser diode module is made suitable for use in systems with considerably higher bit rates than 1 Gbit/s, the aforesaid guide pin (9) forms the inner guide of a coaxial transmission line situated inside the casing, of which transmission line the outer guide (CBL) is electrically conductively connected to the casing, whereas in the connecting line between the inner guide (9) and the laser diode (LD) a resistor (CS) is inserted having a value such that the sum of the resistances of this resistor (CS) and the laser diode (LD) is substantially equal to the characteristic impedance of the coaxial transmission line (9, CBL).

Laser diode module

A laser diode module comprises a rectangular, box-like metal casing having a bottom (B), whereas an even number of guide pins (1-14) are passed through the bottom (B) in a standardized DIL order and no less than one guide pin (5) is electroconductively connected to the bottom (B). In addition to the laser diode (LD) itself the module further includes a Peltier cooler (TEC) and a thermal metal base carrier (BC) coupled thereto, which base carrier accommodates the laser diode (LD), a photodiode (PD), a support (S) for the glass fibre (F) and a thermistor (TH). In order to render this laser diode module suitable for use in communication systems with bit rates that exceed by far 1 Gbit/s, the said guide pin (5) has inside the casing a portion in the form of a rod with a constant cross-section and with no less than one flat side face which over its entire surface has an electroconductive coupling with the relevant long sidewall (SW.sub.1) of the casing, an electroconductive interconnecting strip being provided between the head face of the rod and the base carrier (BC).

A microwave oscillator circuit, suitable for use as the local oscillator in beam transmitters, radar systems and satellite TV receivers, comprises an active element (IMPATT, Gunn diode) at one end of a coaxial transmission line which is terminated at its other end by a matched load. At a suitable distance from the diode a high Q transmission cavity resonator is coupled to the transmission line via a first coupling hole. A drawback of such a circuit is that a portion of the oscillator power at the required oscillator frequency f.sub.o is dissipated in the terminal impedance Z.sub.o. This is obviated by coupling the transmission resonant cavity to the transmission line via a second coupling hole (12, FIG. 1 and FIG. 2). The distance between the first and the second coupling hole is 1/4.lambda.. As a result the terminal impedance, which has been transformed very frequency-selective to a very high value in situ of the second coupling hole, is transformed to a very low value at the first coupling hole and very little power is dissipated in this low impedance, so that a considerable improvement of the circuit efficiency has been achieved.

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Eindhoven, Netherlands

Hindrik Tjassens