A low-noise laser diode module comprises a laser diode for emitting light
with a wavelength in the range from UV to IR, a drive circuit for
injecting electrical current into said diode, and an automatic power
control circuit for monitoring and adjusting laser output power using
front-facet photodiode external to the laser assembly and a feedback
loop. Said drive circuit produces injection current modulated by an RF
signal with variable degrees, depending on the wavelength to be
stabilized, the desired spectral bandwidths of the laser output, and/or
other applications. Said RF signal can be a sine wave, a distorted sine
wave, a rectified sine wave, a non-sine wave, a series of narrow pulses,
or repetitive shunt. The present invention encompasses a method for
producing stable, broadband, and low-coherent laser. The present
invention also encompasses a method for producing stable narrowband or
single longitudinal mode laser. The present invention further encompasses
a compact light source applicable to DPSS lasers, fiber lasers, optical
parametric oscillators, low-speckle laser display systems, and seeders,
with or without nonlinear frequency conversion processes.