Semiconductor laser

Abstract

A semiconductor laser comprises: a first cladding layer of a first conduction type; an active layer stacked on the first cladding layer; and a second cladding layer of a second conduction type stacked on the active layer. The first cladding layer, the active layer and the second cladding layer are made of II-VI compound semiconductors. Pulse oscillation occurs with characteristics of a threshold current I th (A), a threshold voltage V th (V) of the diode composed of the first cladding layer, the active layer and the second cladding layer, a differential resistance R S (Ω) of the diode after the rising, a thermal resistance R t (K/W) and a characteristic temperature T o (K). When two amounts α and β are defined by: α≡(R t /T o )I th V th β≡(R t /T o )R S I th 2 the point (α,β) exists in an area on the α-β plane surrounded by the straight line α=0, the straight line β=0, and the curve ((21n t−1)/t, (1−ln t)/t 2 ) having t as a parameter. The semiconductor laser may include a first optical waveguide layer between the first cladding layer and the active layer and include a second optical waveguide layer between the second cladding layer and the active layer, the first optical waveguide layer and the second optical waveguide layer being made of II-VI compound semiconductors. II-VI compound semiconductors making the first cladding layer and the second cladding layer may be a ZnMgSSe compound semiconductor. A semiconductor laser using II-VI compound semiconductors and having the capability of continuous oscillation at high temperatures including the room temperature is provided.

What is claimed is:  
     
       1. A method of generating laser radiation comprising the steps of: 
       providing a semiconductor laser structure comprising a first cladding layer of a first conduction type;  
       an active layer stacked on said first cladding layer; and  
       a second cladding layer of a second conduction type stacked on said active layer, wherein said first cladding layer, said active layer and said second cladding layer are comprised of II-VI compound semiconductors; and  
       continuously oscillating said semiconductor laser structure at room temperature with characteristics of a threshold current I th (A), a threshold voltage V th (V) of a diode composed of said first cladding layer, said active layer and said second cladding layer, a differential resistance R S (Ω) of said diode, a thermal resistance R t (K/W) and a characteristic temperature T o (K), wherein when α and β are defined as:  
       
         
           α≡(R t /T o )I th V th    
         
       
       
         
           β≡(R t /T o )R S I th   2    
         
       
        such that the point α, β exists in an area on the α-β plane surrounded by the straight line α=0, the straight line β=0, and the curve ((2ln t−1)/t, (1−ln t)/t 2 ) where t is a parameter.  
     
     
       2. The method of generating laser radiation of  claim 1 , wherein said step of providing a semiconductor laser structure comprise a step of: 
       providing a first optical wave guide layer between said first cladding layer and said active layer and including a second optical wave guide layer between said second cladding layer and said active layer, said first optical wave guide layer and said second optical wave guide layer being made of a II-VI compound semiconductor.  
     
     
       3. The method of generating laser radiation of claim  4   1 , wherein said II-VI compound semiconductor forming said first cladding layer and said second cladding layer is a ZnMgSSe compound semiconductor. 
     
     
       4. A method of generating laser radiation comprising the steps of: 
       
         providing a semiconductor laser structure comprising a first cladding layer of a first conduction type;  
       
       
         an active layer stacked on said first cladding layer; and  
       
       
         a second cladding layer of a second conduction type stacked on said active layer, wherein said first cladding layer, said active layer and said second cladding layer are comprised of III-V GaN type compound semiconductors; and  
       
         continuously oscillating said semiconductor laser structure at room temperature with characteristics of a threshold current I   th ( A ),  a threshold voltage V   th ( V )  of a diode composed of said first cladding layer, said active layer and said second cladding layer, a differential resistance R   S (Ω)  of said diode, a thermal resistance R   t ( K/W )  and a characteristic temperature T   o ( K ),  wherein when α and β are defined as:    
       
         
           α≡( R   t   /T   o ) I   th   V   th    
         
       
        β≡( R   t   /T   o ) R   S   I   th   2    
         such that the point α,β exists in an area on the α - β plane surrounded by the straight line α= 0 , the straight line β= 0 , and the curve  ((   2 ln t− 1   )/ t,  (   1 −ln t )/ t   2 )  where t is a parameter.   
     
     
       5. The method of generating laser radiation of  claim 4 , wherein said step of providing a semiconductor laser structure comprise a step of: 
       
         providing a first optical wave guide layer between said first cladding layer and said active layer and including a second optical wave guide layer between said second cladding layer and said active layer, said first optical wave guide layer and said second optical wave guide layer being made of a III-V compound semiconductor. 
       
     
     
       6. The method of generating laser radiation of  claim 4 , wherein said III-V GaN type compound semiconductor forming said first cladding layer and said second cladding layer is a AlGaN compound semiconductor.