DFB laser arrays utilizing CPM-based sampled gratings for precise wavelength control and enhanced single-mode...

Area of Science:

• Photonics and Laser Technology
• Semiconductor Devices
• Optical Engineering

Background:

• Distributed feedback (DFB) lasers are crucial for optical communication.
• Achieving precise multi-wavelength emission and high stability in DFB lasers remains a challenge.
• Existing techniques often involve complex fabrication or limited tunability.

Purpose of the Study:

• To propose and experimentally demonstrate a novel DFB laser array.
• To investigate the effects of continuous phase modulation (CPM) and sampled gratings on laser characteristics.
• To achieve robust, low-cost, high-precision multi-wavelength laser sources.

Main Methods:

• Fabrication of a DFB laser array using micrometer-level lithography.
• Implementation of discrete phase increments to create an equivalent nanometer-scale continuous phase shift.
• Systematic investigation of phase shift order (even vs. odd) and modulation length.
• Characterization of laser wavelength detuning, channel spacing, and side-mode suppression ratio (SMSR).

Main Results:

• Two distinct operating regimes were identified based on phase shift order.
• Even-order phase shifts (CPM-2Nπ) resulted in linear wavelength detuning with ~1.5 nm channel spacing.
• Odd-order phase shifts (CPM-(2N+1)π) demonstrated wavelength locking and superior single-mode stability (SMSR > 60 dB) due to distributed phase shift.
• Optimal modulation length was determined for balancing field uniformity and mode selectivity.

Conclusions:

• The proposed CPM and sampled grating DFB laser array offers precise wavelength control and enhanced stability.
• The odd-order phase shift configuration provides a robust method for achieving high SMSR and wavelength locking.
• This technology presents a cost-effective solution for fabricating high-precision multi-wavelength laser sources for optical communication.