摘要： In recent years, optical frequency combs are gaining attention in many fields of science, e.g. frequency metrology, optical clocks, and high-resolution spectroscopy. Most sophisticated comb sources can be repetition rate stabilized down to 10-16 uncertainty in 1 s averaging time [1] (bounded by the stability of the reference clock). Therefore compact, low-cost and energy efficient fiber-based sources are highly demanded on the market [2]. Accurate thermal stabilization of the fiber laser cavity is the first step to obtain stable repetition frequency, which is critical for optical frequency comb spectroscopy schemes [3]. Moreover, cavity-enhanced spectroscopic techniques like Vernier spectroscopy requires additional detuning of the comb repetition rate from the cavity mode-spacing [4]. We report an experimental investigation of the performance of a Er-doped, low power, thermally stabilized, mode locked laser, utilizing graphene as a saturable absorber. The oscillator, depicted in Figure 1(a), consists of: a hybrid component comprising an output coupler, wavelength division multiplexer and isolator (TIWDM), saturable absorber, and a piezo-electric transducer (PZT). The laser based only on polarization maintaining (PM) fibers, without any free space components. The entire resonator and all components are placed on a custom-made heating plate with uniformly spread heating traces, which equally cover the entire board surface, ensuring perfectly homogenous heat distribution. For efficient thermal stabilization, the fibers are attached to the plate by acrylic adhesive thermopads. The resonator is placed in a 3D-printed enclosure. A custom-made thermal controller is responsible for thermalization of all oscillator components with long term stability better than 0.05°C. Additional tuning of the repetition rate in the range of 0 – 2.79 kHz is performed by means of a piezo stretcher driven with voltages from 0 to 150 V. The stretcher is based on a miniature, monolithic, multilayer piezo stack (5x5x50 mm), which stretches the Er-doped fiber by approximately 36 μm. The fundamental repetition rate (fc), resulting from the cavity length is equal to 124.6539196 MHz at 30°C (without any voltage applied to the PZT). The signal to noise ratio (SNR) in the radio frequency (RF) spectrum measured with 2.7 Hz resolution bandwidth (RBW) is at the level of 70 dB. The repetition rate of the laser can be detuned by 17 kHz via heating the resonator from 30 to 50°C. We believe that such compact, simple frequency combs with low power consumption are suitable for field applications. The presented work was funded by the Foundation for Polish Science (First TEAM/2017-4/39) co-financed by the European Union under the European Regional Development Fund. A.G. acknowledges the support of the Faculty of Electronics (grant “M?oda Kadra”).