US 2006/0215716 A1 · Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths

Abstract

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.

Claims18

Dependent claims

A low-noise laser diode module comprising:

a laser diode for emitting light with a wavelength in the range from ultra-violet to infrared;
a set of optics elements for beam shaping;
a driving circuit connected to said laser for providing drive current with a high frequency modulation of variable degree;
an automatic power control subsystem for adjusting drive current to maintain output power of said laser at a predetermined level;
an optional thermoelectric controller affixed to said laser diode for active temperature control;
and
a housing in which all the above-mentioned components contained.

4 more elements

A method for stabilizing laser output comprising steps of:

selecting laser operation temperature and current to avoid instable zones in the laser diode stability map plotted in the current-temperature coordinates;
periodically disturbing laser operation by intentional change of drive current at an RF rate;
optimization of the frequency and degree of modulation according to the actual applications;
and
automatic optical power control by means of signal sensing and feedback loops.

2 more elements

A compact light source stable in intensity and spectrum, which:

is stabilized by automatic temperature and power or current control and RF modulation;
produces a laser wavelength in the range from UV to IR;
produces a laser spectrum having spectral width from subpicometers to nanometers;
produces a laser beam of full-time low-noise;
produces a laser output with optical power of at least 1 μW;
produces a continuous wavelength sweeping;
and
is operated in CW or pulsed mode.

5 more elements

Dependencies are inferred from the claim text.

Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths

Life of this patent

Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths

Life of this patent

Abstract

Claims18