Generation of picosecond pulses and optical frequency combs with multi-section 1065nm ridge waveguide diode lasers

Abstract

Mode-locked diode lasers generate reliably picosecond or even sub-picosecond optical pulses. Especially, colliding pulse mode-locked (CPM) lasers are promising sources for the generation of short optical pulses with a high repetition frequency. We present experimental results for the generation of ps optical pulses with multi-section ridge waveguide CPM lasers. The lasers with a central emission wavelength of 1065nm consist of an odd number of 100μm long electrically separated sections. CPM operation is achieved by reverse DC biasing the central section which acts as a saturable absorber and forward DC biasing the other (gain) sections. For a cavity length of 1.9mm, passive mode-locking is achieved for a reverse bias of -2.0V applied to the saturable absorber. The repetition frequency is about 43GHz and the pulse length is 3.3ps assuming a sech-pulse shape. The frequency comb spans 6nm assuming a dynamical range of 20dB with a frequency spacing of about 21GHz. At a cavity length of 0.9mm a frequency comb with more than 175 single frequencies over 12nm with a spacing of 45GHz is obtained. Detailed investigations of the optical pulse and frequency comb generation in dependence on cavity length, reverse absorber voltage and DC bias current will be presented.