using standard cleaving procedures a cavity laser diode of the type shown in fig1 is fabricated each diode had a length of about 300 u03bcm and its characteristics were tested at room temperature using 100 ns pulses at a repetition rate of about 1000 pulses per second similar hetero epitaxial ridge overgrown lasers were described in the article entitled 34 a new high power narrow beam transverse mode stabilized semiconductor laser at 1 5 u03bcm the heteroepitaxial ridge overgrown laser 34 by w t tsang and r a logan applied physics letters vol 45 pp 1025 1027 1984 in operation laser 100 is forward biased by a suitable energy source such as a battery not shown connected across contacts 107 and 108 when the current supplied by the energy source exceeds the lasing threshold stimulated coherent radiation is generated by radiative recombination of holes and electrons in layer 103 this radiation emanates from one or both of the end surfaces which may be cleaved or polished optically to form a cavity resonator fig7 shows the light output versus pulsed current of a high quality er doped diode of the type shown in fig1 er doping did not appear to influence the threshold currents or output power provided that er concentration.