Distributed Feedback (DFB) Laser Diode Chip

Description

A Distributed Feedback (DFB) laser diode chip is a type of laser diode chip that uses a grating structure to generate a laser beam. The grating is formed by periodically varying the refractive index of the material in the active region of the laser diode chip.

When a voltage is applied across the p-n junction of the DFB laser diode chip, electrons and holes are injected into the active region, where they recombine and emit photons. The photons are then diffracted by the grating structure, causing them to interfere constructively in a single mode that is aligned with the grating period. This results in a narrow spectral linewidth and a single longitudinal mode.

DFB laser diode chips are widely used in telecommunications and sensing applications because they offer a high degree of spectral stability and a narrow linewidth. They are also less prone to mode hopping than FP laser diode chips. However, they are more difficult to fabricate and typically require higher drive currents than FP laser diode chips.

To improve the performance of DFB laser diode chips, various techniques such as complex coupling coefficients and phase-shifted gratings have been developed to reduce the threshold current and improve the linewidth. Additionally, external cavity techniques such as distributed Bragg reflectors (DBRs) and fiber Bragg gratings (FBGs) can be used to further stabilize the emission wavelength and enhance the output power.

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