Pressure and temperature tuning of InGaP/AlGaInP laser diodes from red to yellow

Abstract

1 Introduction InGaP/AlGaInP laser diodes are commercially available in the 635-690 nm range. Shorter wavelength operation is hampered by increased leakage currents. Meanwhile, the orange and yellow range has some important applications in medicine [1,2] and in optical communication using plastic fibers. So far the yellow range has been achieved by frequency doubling of infrared laser diodes [3][4][5] or by frequency doubling of diodepumped solid state lasers [6].High pressure increases the direct bandgap in III-V semiconductors and has been extensively used to characterize laser diodes [7][8][9][10][11] and to tune their emission wavelength [12][13][14]. For red lasers the pressure tuning can only be performed at low temperature in order to keep leakage currents low. In the present paper we describe L -I -V and spectral measurements of two InGaP/AlGaInP laser diodes in a wide range of pressures (up to 20 kbar) and temperatures (from 300 K down to 80 K). The first sample shows characteristic anomalies in L-I-V at low temperature and high pressure, attributed to impact ionization of holes in pcladdings [15]. The second sample does not show such anomalies and is tuned in the 70 nm range (from 645 nm to 575 nm) with low threshold current and high emission power.