Multi-section tunable laser with differing multi-element mirrors

A diode laser which can be operated at selectably variable frequencies covering a wide wavelength range comprising:

• (a) active section semiconductor means for creating a light beam by spontaneous emission over a bandwidth around some center frequency and for guiding said light beam between opposed ends thereof;
• (b) gain control means connected to said active section semiconductor means for supplying an electrical signal to said active section semiconductor means which causes said active section semiconductor means to have gain sufficient to overcome losses and create an emitted beam of laser light;
• (c) a pair of mirrors bounding said active section semiconductor means on respective ones of said opposed ends thereof, said mirrors each having spaced reflective maxima points providing a maximum reflection of an associated wavelength with the spacing of said reflective maxima points of respective ones of said mirrors being different whereby only one said reflective maxima of each of said mirrors can be in correspondence with a wavelength of the created lightbeam and thereby provide a low loss window at any time, said mirrors each including a plurality of discontinuities to cause said reflective maxima, the spacing of said discontinuities of one said mirror being different from the spacing of said discontinuities of the other said mirror so as to cause the spacing of said reflective maxima to be different in respective ones of said mirrors;
• and,
• (d) means operably connected to said mirrors for independently adjusting an index of refraction of said phase shifter means, said mirrors and said active section semiconductor means.

In a diode laser having,

• active section semiconductor means for creating a light beam by spontaneous emission over a bandwidth around some center frequency and for guiding the light beam between opposed ends thereof;
• gain control means connected to the active section semiconductor means semiconductor means for supplying an electrical signal to the active section semiconductor means semiconductor means which will cause the active section semiconductor means semiconductor means to provide gain to overcome losses and create an emitted beam of laser light;
• a pair of mirrors bounding the active section semiconductor means semiconductor means on respective ones of the opposed ends thereof, the mirrors each having spaced reflective maxima points providing a maximum reflection of an associated wavelength with the spacing of the reflective maxima points of respective ones of the mirrors being different whereby only one the reflective maxima points of each of the mirrors can be in correspondence with a wavelength of the created lightbeam and thereby provide a low loss window at any time, the mirrors each including a plurality of discontinuities causing the reflective maxima points, the spacing of the discontinuities of one mirror being different from the spacing of the discontinuities of the other mirror so as to cause a wavelength spacing of the reflective maxima points to be different in respective ones of the mirrors;
• and,
• phase shifter semiconductor means disposed between the active section semiconductor means and one of the mirrors for adjusting the round trip cavity phase between the mirrors and thus a lasing mode wavelength of the diode laser, the method of operation at selectably variable frequencies covering a wide wavelength range comprising the steps of:
• (a) connecting vernier control circuit means to the mirrors to provide a selectably adjustable electrical signal to the mirrors which can cause continuous tuning within a frequency band;
• (b) connecting offset control circuit means to the mirrors to provide an electrical signal to the mirrors which can shift the reflective maxima of the mirrors into alignment at a desired frequency mode;
• (c) connecting phase control circuit means to the phase shifter semiconductor means to adjust the round trip cavity phase between the mirrors;
• (d) using the offset control circuit means to shift the reflective maxima of the mirrors into alignment at a desired frequency mode;
• (e) using the vernier control circuit means to tune the laser within a frequency band adjacent the frequency mode selected by the offset control circuit means;
• and,
• (f) using the phase control circuit means in synchronism with the vernier control circuit means to align the wavelength of the lasing mode wavelength of the diode laser to be the same as the wavelength of said low loss window.