It is reported that gain saturation of single quantum wells in lasers with wavelength-selective elements such as GSE (grating-coupled surface-emitting) lasers is the cause of high threshold current densities. Thus, if the SQW is replaced by a double quantum well (DQW) structure one would expect the laser to function more efficiently. To verify this hypothesis the authors compared the spontaneously emitted light from the lowest and second quantum states from SQW and DQW cleaved lasers with a long unpumped region. Above 1.6 kA/cm2 (400 mA) the spontaneous emission, or gain, in the SQW laser's first excited state is greater than that in the ground state. Nearly all of the increased emission with drive current above 1.6 kA/cm2 is due to the higher energy state. Spontaneous emission from the second quantum level begins at approximately 600 A/cm2, at which level current is lost to the gain at 800 nm. At about 350 mA, or 1.2 kA/cm2, the gain in the excited quantum state is approximately equal to that in the ground state.
|Number of pages||1|
|Journal||Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS|
|State||Published - 1989|
|Event||Second Annual Meeting of the IEEE Lasers and Electro-Optics Society - LEOS '89 - Orlando, FL, USA|
Duration: 17 Oct 1989 → 20 Oct 1989