MITSUBISHI

MITSUBISHI LASER DIODESML6XX1A SERIESFOR OPTICAL INFORMATION SYSTEMSI Far-field patternThe ML6XXI A laser diodes lase in fundamentaltransverse (TEee) mode and the mode does notchange with the current. They have a typicalemitting area (size of· near - field pattern) of0.7 x 2.0 pm'· Fig. 8 show typical farfield radiationpatterns in "parallel" and "perpendicular" planes.The full angles at half maximum points (FAHM)are typically 12· and 30·.'5S:JoFig. 7 Far- field patterns in plane parallelto heterojunctions ellell-30Off-axis angle (deg.)Fig. 8Far- field patterns in plane perpendicularto heterojunctins e.l'5c.'5oOff- axis angle (deg.)II Pulse response waveformIn the digital optical transmission systems, theresponse waveform and speed of the light outputagainst the input current pulse waveform is one of. the main concerns. In order to shorten theoscillation delay time, the laser diode is usuallybiased close to the threshold current, Figure 9shows a standard response waveform obtained bybiasing ML6XXI A to Ith and applying a squarepulse current (top of Fig. 9) up tol OmW. A Quickresponse is obtained with rising and falling timesbeing 0.3ns and O.4ns typical respectively.Fig. 9Pulse response waveformTime (nsec.)2 -104'. . MITSUBISHI..... ELECTRIC