Temperature compensating semiconductor lasers

A temperature compensating semiconductor laser comprising:

• a semiconductor laser chip;
• a substrate on which said chip is mounted;
• a support member mounted on said substrate said support member having a different thermal expansion coefficient from that of said substrate;
• a reflector mounted on said support member and aligned with an internal optical cavity of said chip;
• said chip and said reflector forming a composite optical cavity comprising said internal optical cavity of said chip and an external cavity part of shorter optical path length comprising a space between the chip and an external surface of said reflector, said substrate and said support member having thermal expansion coefficients such that in response to temperature changes the reflector moves such that the thermal expansion coefficient of the space between said external surface of the reflector and the nearest external surface of said semiconductor chip is such that said external cavity part has a thermal expansion coefficient substantially matched with the peak gain wavelength expansion coefficient of said internal optical cavity according to the equation (dL.sub.A /dT)(1/L.sub.A)=(d.lambda..sub.p /dT(1/.lambda..sub.p) where L.sub.A is the distance between said external surface of said reflection and said external surface of said semiconductor chip, .lambda..sub.p is the peak wavelength, and T=Temperature.

A temperature compensating semiconductor laser comprising:

• a semiconductor laser chip;
• a substrate on which said chip is mounted;
• a support member mounted on said substrate said support member having a different thermal expansion coefficient from that of said substrate;
• a reflector mounted on said support member and aligned with an internal optical cavity of said chip;
• said chip and said reflector forming a composite optical cavity comprising said internal optical cavity of said chip and an external cavity part of shorter optical path length comprising a space between the chip and an external surface of said reflector, said substrate and said support member having thermal expansion coefficients such that in response to temperature changes the reflector moves such that the thermal expansion coefficient of the space between said external surface of the reflector and the nearest external surface of said semiconductor chip is such that said composite optical cavity has a mode wavelength expansion coefficient substantially equal to zero as represented by the equation dL.sub.A /dT=-dL.sub.S /dT where L.sub.A is the distance between said external surface of said reflector and said external surface of said semiconductor chip, L.sub.s is the optical path length of said semiconductor chip, and T is temperature.

A temperature compensating semiconductor laser comprising:

• a semiconductor laser chip;
• a substrate on which said chip is mounted;
• a support member mounted on said substrate said support member having a different thermal expansion coefficient from that of said substrate;
• a reflector mounted on said support member and aligned with an internal optical cavity of said chip;
• said chip and said reflector forming a composite optical cavity comprising said internal optical cavity of said chip and an external cavity part of shorter optical path length comprising a space between the chip and an external surface of said reflector, said substrate and said support member having thermal expansion coefficient such that in response to temperature changes the reflector moves such that the thermal expansion coefficient of the space between an external surface of the reflector and the nearest external surface of said semiconductor chip is such that provide said composite optical cavity with a mode wavelength expansion coefficient substantially equal to the peak gain wavelength expansion coefficient of said internal optical cavity according to the equation (dL.sub.C /dT)(1/L.sub.C)=(d.lambda..sub.p /dT)(1/.lambda..sub.p) where L.sub.C is the optical path length of said composite optical cavity, .lambda..sub.p is peak wavelength, and T is temperature.