[OPTICAL REVIEW Vol. 7, No. 6 (2000) 520-524]

Thermal- and Spectral-Characteristics of High-Power Quasi-Continuous Wave 940-nm InGaAs Diode Laser Arrays

Toshiyuki KAWASHIMA,1 Tomokazu ICHII,1 Takeshi KANZAKI,2 Masanobu YAMANAKA,1 Yasukazu IZAWA,1Sadao NAKAI1 and Hirofumi KAN2

1Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka, 565-0871 Japan, 2Central Research Laboratory, Hamamatsu Photonics K. K. 5000, Hirakuchi, Hamakita, Shizuoka, 434-8601 Japan

(Received June 21, 2000; Accepted September 5, 2000)

Experimental results of the thermal and spectral characteristics of a monolithic stack of high power quasi-continuous wave 940-nm InGaAs linear laser diode arrays have been evaluated. Thermal resistance as the most important thermal parameter characterizing a high-power laser diode package was obtained using the temperature rise measured directly by a thermo-camera. A new simple and convenient technique to measure a spectral transition of the emission from laser diode arrays is proposed. Spectral chirping due to the transient thermal power dissipated during the laser pulse was observed as a time-evolution of the spectral profile; it gave a comprehensible image of the chirping behavior. Comparing the temperature rise in the diode junction with the thermal simulation, it was determined that the thermal shift of central wavelength dλ/dT was 0.21 nm/°C. Detailed performances were identified for pumping a Yb3+ doped crystalline laser, and it was verified that the laser diode arrays were satisfactory to meet pumping source requirements for coupling to Yb3+ absorption linewidth.

Key words : laser diode array, InGaAs, diode-pumped solid-state laser, thermal resistance, chirping