Multisection waveguide method for facet temperature reduction and improved reliability of high-power laser diodes

Abstract

Catastrophic optical mirror damage (COMD) limits the output power and reliability of lasers diodes (LDs). Laser selfheating together with facet absorption of output power cause the facet to reach a critical temperature (Tc), resulting in COMD and irreversible device failure. The self-heating of the laser contributes significantly to the facet temperature, but it has not been addressed so far. We implement a multi-section waveguide method where the heat is separated from reaching the output facet by exploiting an electrically isolated window. The laser waveguide is divided into two electrically isolated laser and transparent window sections. The laser section is pumped at high current levels to achieve laser output, and the passive waveguide is biased at low injection currents to obtain a transparent waveguide with negligible heat generation. Using this design, we demonstrate facet temperatures lower than the junction temperature of the laser even at high output power operation. While standard LDs show COMD failures, the multi-section waveguide LDs are COMD-free. Our technique and results provide a pathway for high-reliability LDs, which would find diverse applications in semiconductor lasers.

COMD-free continuous-wave high-power laser diodes by using a multi-section waveguide method

“…This study uses a multi-section waveguide method shown in Figure 1 to effectively separate laser heat load from the output facet, hence strongly reducing facet temperature even below the laser cavity temperature developed in our previous work [19,20]. In this work, we fabricated and carried out detailed characterization of the devices, studied their optimum working conditions, and revealed the elimination of COMD in LDs [21,22]. The LD waveguide is divided into two sections, laser and passive waveguide, which gives electrical and thermal isolation.…”

Narrow versus broad waveguide laser diodes: a comparative analysis of self-heating and reliability

“…Therefore, understanding and preventing COD is essential for improving the reliability and output power of LDs. Several approaches have been proposed to mitigate COD, such as current blocking [9,10], surface passivation [11][12][13], non-absorbing mirrors [14,15], quantum well intermixing [16][17][18][19], and multi-section waveguide design [20][21][22][23]. To study the thermal behavior and heating mechanisms of LDs, various experimental and computational methods have been employed, such as micro photoluminescence [24], Raman spectroscopy [25], infrared scanning near-field optical microscopy [26,27], thermoreflectance spectroscopy [28][29][30][31][32], analytical models [35][36][37][38][39], and numerical simulations [40][41][42][43].…”

48W continuous-wave output power with high efficiency from a single emitter laser diode at 915nm

“…Along with the rapid development of fiber lasers, high power and PCE have become more critical to provide a cost-effective laser diode. To increase the output power [9,10] and power conversion efficiency [11], epitaxial design methods [12][13][14][15], epitaxial growth technologies [16,17], facet reliability against COMD [18][19][20][21], and passivation technologies [8,22,23] have been greatly improved. Increasing the reliable output power and PCE are always fundamental pursuits in research and practical applications.…”