Unlocking Clearer Images: Enhancing Laser Precision and Reducing Noise in FDML Lasers for Medical Imaging

Industry: The research focuses on the optics and photonics industry, specifically in the development and optimization of laser technologies for applications such as optical coherence tomography (OCT) in medical imaging.

Challenge: The main challenge addressed in this study is the impact of chromatic dispersion on the coherence length and noise of Fourier Domain Mode Locked (FDML) lasers. These factors are critical for ensuring high-quality imaging and accurate measurements in applications like OCT.

How the GaGe Digitizer Was Used: The GaGe Digitizer (model CS12400) was utilized to sample the signal received from the laser at a rate of 200 MS/s with a 12-bit resolution. This high sampling rate and resolution were essential for accurately capturing and analyzing the laser’s noise and coherence properties.

Extraordinary Aspects of the Paper: The paper demonstrates a significant reduction in laser linewidth, achieving an instantaneous linewidth of 20 pm. It also highlights the laser’s exceptional relative intensity noise (RIN) performance, achieving -136 dBc/Hz. Additionally, the study introduces a robust method to measure coherence and noise properties, which can be beneficial for optimizing FDML lasers for various applications.

Equipment & Sensors Used:

GaGe Digitizer: Model CS12400, 14-bit ADC, 200 MS/s sampling rate (GaGe Applied Technologies).

Ultrasonic Transducer: A custom-fabricated 30 MHz piezo-composite linear array with 64 elements, each measuring 2 mm × 85 μm, and a pitch of 100 μm.

Amplifiers: AD8331 (Analog Devices): Variable gain amplifier, MAX4107 (Maxim Integrated Products): Optional second amplifier.

Filters:

PBP-35W (Mini-Circuits): Band-pass filter with −3 dB bandwidth of 88%.

BBP-30 (Mini-Circuits): 30 MHz band-pass filter with −3 dB bandwidth of 30%.

BLP-10.7 (Mini-Circuits): Low-pass filters with −3 dB cut-off frequency of 14 MHz.